Layer by Layer Conference Review

VDR-Abstract-Schicht-CoverFrom June 9th – 11th 2016, an interdisciplinary conference for conservators, curators, and art scholars was held in Kassel, Germany, organized by the paintings specialty group of the German Association of Conservators (Verband der Restauratoren VDR) and the Museum Landscape Hessen Kassel (Museumslandschaft Hessen Kassel). The conference’s topic “Layer by Layer – The significance and aesthetic of the surface” (Schicht um Schicht – Die Bedeutung und Aesthetik der Oberflaeche) aimed to give an extended view on various types of objects focusing on surfaces in all their facets and raised thought-provoking questions. What importance do we ascribe to the original surface when we look at an object? What impact do irreversible conservation treatments have on our aesthetical perception of an object? How do conservators, curators, artists, and visitors observe, describe and interpret surfaces?

On the one hand, observations and interpretations happen through visual and scientific examination, based on experience and analysis of conservators and scientists. On the other hand art historians analyze objects and their surfaces in their historical context. Perception psychologists who also participated noted that these kinds of different interpretations are not just a result of a profession or particular methods, but are also influenced by individual interests and especially individual perception.

The title of the conference already implied that the talks wouldn’t just scratch the surface, thus not just give a superficial overview of an objects surface, but rather go in depth. Presentations and following conversations discussed how various layers and sometimes damages within them affect the character of the surface – intended or not.

Furthermore, the variety of presented objects, speakers from different fields of conservation and speakers from other disciplines showed the broad range and importance of the topic: surface. The conference offered a platform for participating experts from various fields to discuss their experience and opinions. However, it also showed us that we will continue to struggle with defining and describing specific appearances, causes and effects as we face the limitations of our individual perceptions and terminology. Lastly, the conference highlighted the importance of continuing conversations across fields, where accurate and clear terminology can be incredibly beneficial. Ultimately, improved communication and understanding will benefit the object, its preservation and presentation, and is nevertheless essential for our decision making process.

 As most of the conference was held in German, this English summary has been provided to encourage and support a transnational exchange of ideas and information. The following outline is based on the conference’s booklet with its short abstracts, notes taken by the author of this post and a German review written by Cornelia Peres and Dirk Welich. For more specific information please contact


  • Anne Harmssen: About finiteness of immaculately beautiful surfaces
  • Nathalie Baeschlin: Fragile and precious – tense painting surfaces of the 20th century
  • Dr. Helmut Leder: Perception of art from an empirical aesthetic research point of view. Is it a question about style?
  • Dietmar Wohl: Assertions about surfaces of paintings in the theories of conservation and restoration
  • Dr. Martina Sitt: Still not close enough? Problems about exchange of knowledge between art history and conservation
  • Sybille Schmitt: Systematic tools and resources to determine and evaluate surface and structure on baroque paintings
  • Cornelius Palmbach: Active Thermography – visualization of damages and hidden structures in paint layers and other coated surfaces
  • Theresa Braeunig: Crucifix – reconstruction and composition of a late Gothic work using 3D-technology
  • Susanne Litty, Mira Dallige-Smith: Brilliant sh(r)ine – the complexity of original and alteration shown on a North Indian miniature-altar as an example
  • Thomas Kraemer: Changes in a paintings surface through thinning or removing varnishes. An example from the Gemaeldegalerie Alte Meister in Kassel
  • Joerg Klaas: “Like greyblue painted surfaces” – Alterations of ultramarine containing paint layers in easel paintings
  • Linda Haselbach, Dr. Albrecht Pohlmann: Efflorescence, blanching, protrusions – Fatty acid dissociation and lead soap building in oil studies by Adolf Senff
  • Andreas Krupa: Reconstruction as a conservation treatment? – Sheen and color of a furniture surface with mahogany-appearance
  • Andreas Hoppmann: Varnish separation on a triptych by Bartholomaeus Bruyn the Elder
  • Sabine Formanek: A surface that is polished with “chalk and water and a piece of felt till it appears like glass” restoration of a tabletop with a transfer decoration
  • Jonathan Bikker: What’s so funny about impasto? Arnold Houbraken’s lampooning of Rembrandt’s use of texture in perspective; Talk given in English
  • Stefanie Lorenz: Conservation of River scenery by Jacob Philipp Hackert, 1805. A method for a layer selective varnish removal
  • Babett Forster, Romy Koenig-Weska: The portrait as a palimpsest. Layer by layer in scholar portraits from Jena
  • Felix Muhle: Delicate sheen: Polished white bole in abbot Anselm II.  “Wohncabinet” in cloister Salem, Southern Germany
  • Eva Bader: Surface cleaning of the installation Barraque D’Dull Odde by Joseph Beuys at the Kaiser Wilhelm Museum in Krefeld, Germany
  • Franziska Bolz: Shoe-paste, sand and fire – artificial aging as a part of Tingatinga-paintings from Tanzania (East Africa)
  • Caroline von Courten: The Photographic Surface as Interface in mixed-media photo-works: Layers of materials, processes and meanings in Ger van Elk’s Dutch Grey, 1983/84
  • Dr. Dietmar Ruebel: Handcraft and machine aesthetic – surfaces as internal memory of 20th and 21st century art
  • Helena Ernst: The Keep by Mike Kelley at the Museum Brandhorst, Munich, Germany

The conference opened with an introduction given by Justus Lange, who demonstrated how different surfaces are perceived nowadays and how they have been perceived in the past. By discussing initial ontological issues of surfaces, he showed how relative and subjective the appraisal process of a surface can be and thus, prefaced the first session of the three-day long, interdisciplinary conference.

Anne Harmssen: Von der Endlichkeit makellos schoener Oberflaechen
Anne Harmssen: About finiteness of immaculately beautiful surfaces

Anne Harmssen presented in the first talk of the conference a three dimensional object by contemporary artist Carola Keitel called O 11 (Objekt 11). Her work perfectly represented the conference’s theme and showed how essential the material properties – and therefore surface and texture can be essential for an object’s meaning. Harmssen described Keitel’s meticulous method of treating the object’s metal surface, in which she has used a regular trashcan and transformed it to an artwork with an absolute pristine surface. Due to a damage on the object, Harmssen was confronted with the question whether or not and how to repair the damage in an immaculate surface. The artist herself saw the integrity of the piece compromised and hence the object itself destroyed. Harmssen, who is also owner of the object, decided not to follow the artist’s suggestion to grind the entire surface down, therefore recreating a pristine and perfect surface again, but rather decided to conduct a localized treatment. The talk was followed by a discussion as to whether the existence of this particular object is founded on its surface and can only be justified by its immaculate state and whether the object’s integrity and perfection is more important than its history.

Nathalie Baeschlin: Fragil und prezioes – spannungsvolle Gemaeldeoberflaechen des 20. Jahrhunderts
Nathalie Baeschlin: Fragile and precious – “tense” painting surfaces of the 20th century

Following Harmssen, Nathalie Baeschlin presented a paper based on several examples, such as paintings by Picabia and Mondrian and objects of raku ware, where either the fragility of the surface or the entire layer structure can be essential part of the artwork if intended by the artist. For example, she described how Picabia experimented with crackle lacquer and other methods to create intentional fissures through layering. However, her remarks about the surfaces of 20th century paintings and their intended fragility made clear that special properties of a surface can be intrinsic to the object, thus untouchable as an element of its meaning.

Prof. Dr. Helmut Leder: Wahrnehmung von Kunst aus der Sicht der empirischen Aesthetikforschung. Eine Frage des Stils?
Prof. Dr. Helmut Leder: Perception of art from an empirical aesthetic research point of view. Is it a question about style?

Unlike Baeschlin, Prof. Dr. Helmut Leder as well as Dietmar Wohl, focused on the unintentional changes in surfaces and discussed how viewers perceive them. Among other substantial aspects of perception, Leder presented a model of aesthetic processing, in which aesthetic experiences involve five stages: perception, explicit classification, implicit classification, cognitive mastering and evaluation. Leder presented results of perception studies regarding questions of an artist’s style: How long does it take to perceive style? Do we see style as the means of how the art object was created or produced?

Further reading: Leder et al.: A model of aesthetic appreciation and aesthetic judgments, in: British journal of Psychology Vol 95, Issue 4, 2004, pp. 489-508.

Dietmar Wohl: Aussagen in den Theorien der Konservierungs- und Restaurierungswissenschaft zur Oberflaeche von Gemaelden
Dietmar Wohl: Assertions about surfaces of paintings in the theories of conservation and restoration

Dietmar Wohl explained how an increasing “scientification” of conservation and restoration leads to various sub disciplines, each one with its own theories, e.g. practical conservation, conservation history and technical art history.

Prof. Dr. Martina Sitt: Noch nicht nah genug? Problem des Wissenstransfers zwischen Kunstgeschichte und Restaurierung
Prof. Dr. Martina Sitt: Still not close enough? Problems about exchange of knowledge between art history and conservation

Prof. Dr. Martina Sitt illustrated how contributions by conservators in museum and exhibition catalogs in recent years have enriched our knowledge about an artist’s oeuvre. However, incorporation of these contributions within the analysis of a work is often still insufficient. New information and knowledge gained through conservation treatment and examination are often presented as raw data, not communicated well enough and hence difficult to integrate accurately. This unfortunately results in a crux of two different specific terminologies used in two different fields attempting to discuss the same object. Based on paintings by Teniers, van Delen and Gruenewald, Dr. Sitt’s talk discussed possibilities and problems of exchange between the two fields in a very clear and enriching way.

Sybille Schmitt: Systematische Hilfsmittel zur Bestimmung und Bewertung von Oberflaeche und Struktur an barocken Gemaelden
Sybille Schmitt: Systematic tools and resources to determine and evaluate surface and structure on baroque paintings

As Sybille Schmitt could not present her talk in person, a colleague read her paper, which outlined the importance of an accurate terminology when it comes to describing layer structures, especially on a microscopic scale. By drawing an analogy to geomorphology and its terminology used to characterize variances in layer structure and surface, she introduced a helpful toolkit to conservators that both, describes and evaluates surface changes in paint layers. Despite huge differences in scale between microscopic cross sections of paint layers and the earth’s stratigraphy, the comparison of different phenomena created by physical, chemical or biological processes and forces was very persuasive to me. An example, which compared layer deformation caused by lead soap building to geomorphological deformation was fascinating and surprisingly accurate. It remains uncertain, if and when conservators will choose to adopt this toolkit or terminology.

Cornelius Palmbach: Aktive Thermografie – Visualisierung von Schaeden und verborgenen Strukturen an Malschichten und anderen Oberflaechen
Cornelius Palmbach: Active Thermography – visualization of damages and hidden structures in paint layers and other coated surfaces

Cornelius Palmbach gave an impressive overview of an Active Thermography project conducted at the Bern University of applied sciences BFH (Bern, Switzerland). Palmbach used Active Thermography as a non-destructive imaging technique to locate, visualize, and quantify both hidden structures and damages located beneath coated surfaces. Through subtle and periodical warming of an object’s surface, underlying areas that differ in their thermic properties give different responses that can be then detected with an IR-camera (Lock-In thermography). Palmbach presented convincing examples as he illustrated the identification of lifting paint layers, veneer, and plaster.

Theresa Braeunig, Joerg Maxin, Iris Winkelmeyer: Kruzifix! Rekonstruktion und Gestaltung eines spaetgotischen Werkes mittels 3D-Technik
Theresa Braeunig: Crucifix! Reconstruction and composition of a late Gothic work using 3D-technology

Theresa Braeunig discussed the examination of a nearly life-sized, late Gothic crucifix at the Lenbachhaus Munich, Germany. The project also involved the reconstruction and visualization of missing form elements and alterations in color design and the application of modern technology. 3D scanning and 3D printing helped visualizing the object’s appearance with different color designs from different time periods. Her work resulted in an exhibition dedicated to the research results and visualizations.

Further reading: Theresa Braeunig, Joerg Maxin, Iris Winkelmeyer: 3D-Rekonstruktion der Gestaltung eines spaetgotischen Kruzifixes aus Franz von Lenbachs Sammlung, in: Zeitschrift fuer Kunsttechnologie und Konservierung, Vol. 1, 2016, pp. 183-196.

Susanne Litty, Mira Dallige-Smith: Glaenzender Sch(r)ein – die Komplexitaet von Original und Ueberarbeitung am Beispiel eines nordindischen Miniaturaltars
Susanne Litty, Mira Dallige-Smith: Brilliant sh(r)ine -the complexity of original and alteration shown on a North Indian miniature-altar as an example

Susanne Litty described examination results of a miniature shrine in the collection of the Ethnologisches Museum, Berlin, Germany. The core theme to her talk was the difference between original and altered material, and related issues involving treatment-based decisions. The identification of a later application of a high gloss varnish, also known as “Soluble Nylon”, was one of the main challenges.

Thomas Kraemer: Veraenderungen der Bildoberflaeche bei der Duennung oder Abnahme von Firnissen. Ein Beispiel aus der Kasseler Gemaeldegalerie Alter Meister
Thomas Kraemer: Changes in a paintings surface through thinning or removing varnishes. An example from the Gemaeldegalerie Alte Meister in Kassel

Thomas Kraemer presented a treatment of the painting White Hen with Small Cake by Melchior de Hondecoeter, in the collection of the Gemaeldegalerie Alte Meister in Kassel, Germany. Kraemer’s talk focused on a highly solvent sensitive intermediate varnish layer that made the accurate removal and/or thinning of the top varnish layer with organic solvents impossible. Furthermore, the top varnish was discolored and had evolved a bark-like texture. Even though Kraemer had some success using a mastic resin-powder for mechanical varnish removal, he sought further improvement of the cleaning results.

Further reading: Thomas Kraemer: Veraenderungen der Bildoberflaeche bei der Duennung oder Abnahme von Firnissen. Ein Beispiel aus der Kasseler Gemaeldegalerie Alter Meister, in: VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 1, 2017, pp. 26-34.

Dr. Joerg Klaas, Dr. Heike Stege: “Wie graublau angestrichene Flaechen” – Die Veraenderungen ultramarinhaltiger Farbschichten in der Tafelmalerei
Dr. Joerg Klaas: “Like greyblue painted surfaces” – Alterations of ultramarine containing paint layers in easel paintings

Dr. Joerg Klaas’ presentation focused on “ultramarine sickness” in paintings. Klaas has worked on this degradation phenomenon for several years and published about it in his dissertation at the TU Munich in 2010/11. Within this project, his research covered the examination of paintings from 1475-1720. The examination of several paintings from this time period and mock-ups indicates that the “ultramarine sickness” is not a chemical discoloration, but rather a separation of pigment and binder that causes ultramarine containing layers to appear opaque and lighter or grey.

Further reading: Dissertation in German

Linda Haselbach, Dr. Albrecht Pohlmann: Ausbluehungen, Weissschleier, Protrusionen: Fettsaeureabspaltungen und Schwermetallseifen in den Oelstudien des deutsch-roemischen Malers Adolf Senff (1785-1863)
Linda Haselbach, Dr. Albrecht Pohlmann: Efflorescence, blanching, protrusions: Fatty acid dissociation and lead soap building in oil studies by Adolf Senff

Haselbach and Pohlmann showed a variety of botanical studies by Adolf Senff, most of them executed in oil on paper. 59 similar studies are in the collection Kunstmuseum Moritzburg in Halle (Saale), Germany. Several studies show varying amounts of degradation on the surface including efflorescence, blanching, and protrusions. Haselbach, who wrote her master’s thesis on this project, discussed possible causes for the types of degradation and suggested different treatment options, such as removal, inpainting, varnishing and preventive methods.

Further reading:

  • Thesis in German
  • Linda Haselbach, Dr. Albrecht Pohlmann: Ausbluehungen, Weissschleier, Protrusionen: Bildung von Schwermetallseifen in den Oelstudien des deutsch-roemischen Malers Adolf Senff (1785-1863), in: VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 1, 2017, pp. 7-18.

Andreas Krupa: Rekonstruktion als restauratorische Massnahme? – Glanz und Farbe einer Moebeloberflaeche mit Mahagoni-Optik
Andreas Krupa: Reconstruction as a conservation treatment? – Sheen and color of a furniture surface with mahogany-appearance

Andreas Krupa discussed the difficult conservation treatment of a Biedermeier escritoire (1840, Northern Germany). Cumulative light exposure resulted in a faded and matte appearance of the escritoire that contrasted with other examples of furniture from that time period. These examples were still in good condition and showed a rich, saturated, glossy and Mahogany-red surface. However, several attempts to re-saturate the surface of the escritoire either failed or lead to unsatisfying results. Poor results led Krupa to build a reconstruction following historical models and recipes, gaining unexpected experience and outcomes.

Publication in VDR Beitraege zur Erhaltung von Kunst- und Kulturgut pending.

Andreas Hoppmann: Firnistrennung an einem Triptychon von Bartholomaeus Bruyn der Aeltere – Ein wahrgenommener Gluecksfall
Andreas Hoppmann: Varnish separation on a triptych by Bartholomaeus Bruyn the Elder

Andreas Hoppmann presented one of those rear case studies where a selective varnish removal was conducted. On a Triptych by Bartolomaeus Bruyn (the Elder) a heavily discolored varnish was removed by using an alkaline buffer solution. Conservators were able to separate the top layer of oil-containing varnish from the resinous varnish underneath without damaging lower layers. The selective cleaning revealed a barely discolored resinous varnish layer that was in good condition.

Further reading: Andreas Hoppmann, Firnistrennung an einem Triptychon von Bartholomaeus Bruyn der Aeltere: Ein wahrgenommener Gluecksfall, in: VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 2, 2016, pp. 96-101.

Sabine Formanek: Eine Oberflaeche die mit “Kreide und Wasser und einem Stueck Filz solange geschliffen, bis es wie Glas ist” – Die Restaurierung einer Tischplatte mit Umdruckdekor
Sabine Formanek: A surface that is polished with “chalk and water and a piece of felt till it appears like glass” – restoration of a tabletop with a transfer decoration

Sabine Formanek showed her treatment of a table that was designed using an unusual transferware technique (1830, Museum fuer Angewandte Kunst, Vienna, Austria). Formanek described the transfer technique itself, damages and condition issues, and various treatment steps including consolidation, cleaning, filling, inpainting.

Further reading: Die Restaurierung eines Tisches mit Umdruckdekor aus dem Bestand des MAK Wien

Dr. Jonathan Bikker: What’s so funny about impasto? Arnold Houbraken’s lampooning of Rembrandt’s use of texture in perspective; Talk given in English

Dr. Jonathan Bikker from the Rijksmuseum illustrated Rembrandt’s various ways of manipulating paint to create surface texture, such as his early use of the butt-end of his brush or a palette knife, which he used later in his career. Bikker also discussed how Arnold Houbraken, Dutch painter and writer in the Golden Age, criticized Rembrandt for this “rough” manner of painting, which contrasted with the fine and the loose manner exemplified by Frans Hals.

Stefanie Lorenz: Die Restaurierung des Gemaeldes “Flusslandschaft” von Jacob Philipp Hackert – Eine Methode zur schichtenselektiven Firnisabnahme
Stefanie Lorenz: Conservation of River scenery by Jacob Philipp Hackert, 1805 – A method for a layer selective varnish removal

Stefanie Lorenz presented the treatment of a painting by Jacob Philipp Hackert in the collection of the Alte Nationalgalerie, Berlin, Germany. Lorenz’s self-described greatest challenge of the treatment was the cleaning of the painting, which had a discolored and patchy surface appearance. Close examination revealed five different varnish layers in dark areas whereas bright areas, such as the sky, showed less layers, but also some intermingled ones. Furthermore, there was evidence for residues of an original varnish, which complicated varnish removal using free solvents. Based on this initial situation, Lorenz tested several treatment options for cleaning and presented an interesting and successful mechanical varnish removal using a melamine resin sponge.

Further reading: Stefanie Lorenz: Die Restaurierung des Gemaeldes Flusslandschaft von Jacob Philipp Hackert. Eine Methode zur schichtenselektiven Firnisabnahme, in: VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 1, 2017, pp. 19-25.

Dr. Babett Forster, Romy Koenig-Weska: Das Bildnis als Palimpsest – Schicht um Schicht in Jenaer Gelehrtenbildnissen
Dr. Babett Forster, Romy Koenig-Weska: The portrait as a palimpsest – Layer by layer in scholar portraits from Jena

Dr. Babett Forster and Romy Koenig-Weska showed a variety of portraits from the University in Jena, Germany. From 1548 to the late 18th century, many scholars donated their portraits, often equipped with inscriptions, to the university. Research by Foster and Koenig-Weska has shown, that many of these inscriptions were altered through the centuries. However, some of these covered and overwritten inscriptions start reappearing or are getting uncovered by conservators. The presentation emphasized a complex discussion concerning the preservation and presentation of those portraits in consideration of factors, such as legibility and importance of historic alterations and documents, aesthetics of the portrait, and possible treatment solutions.

Dr. Felix Muhle: Empfindlicher Glanz: Die Fassungen auf Porcellain-Arth im “Wohnkabinet” Abt Anselms II. In Kloster Salem
Dr. Felix Muhle: Delicate sheen: Polished white bole in abbot Anselm II. “Wohncabinet” in cloister Salem, Southern Germany

Felix Muhle discussed the “Wohncabinet” of Abbot Anselm II, at cloister Salem, Germany, focusing on the plaster and furniture elements, which were added by Johann Georg Dirr between 1763-1766. Muhle stated that furniture, sculptures and plaster frames were mostly preserved with their original polished white bole that is imitating porcelain. The presentation covered technical as well as aesthetic aspects of sheen and material imitation and discussed possibilities and limits of cleaning and reduction of grime on water sensitive surfaces.

Eva Bader: Die Oberflaechenreinigung der Installation “Barraque D’Dull Odde” von Joseph Beuys im Kaiser Wilhelm Museum Krefeld
Eva Bader: Surface cleaning of the installation Barraque D’Dull Odde by Joseph Beuys at the Kaiser Wilhelm Museum in Krefeld, Germany

In 1977 Joseph Beuys himself installed Barraque D’Dull Odde at the Kaiser Wilhelm Museum in Krefeld, Germany. The work consists of 650 individual pieces embracing felt, food, dead bees, piles of loose chalk, a dust painting and many other curiosities. This installation represents one of the last “untouched” pieces by Beuys. The preservation of the original installation as well as the great variety of materials complicated the removal of dust that accumulated in almost 40 years. Eva Bader brillantly discussed not just Beuys work process, intentions and created effects, but also presented several conservation approaches for surface cleaning such a complex installation as well as suggested options regarding preventive conservation.

Franziska Bolz: Von Schuhcreme, Sand und Feuer – Kuenstliche Alterung als Bestandteil von Tingatinga-Gemaelden aus Tansania (Ostafrika)
Franzska Bolz: Shoe-paste, sand and fire – artificial aging as a part of Tingatinga-paintings from Tanzania (East Africa)

Franziska Bolz presented her extensive research on Tingatinga style paintings, named after the creator Edward Saidi Tingatinga, who painted in Tanzania at the end of the 1960s. Before he died in 1972, he taught his technique to friends and family members, many of who continued to make Tingatinga-paintings. The paintings are known for their high gloss lacquer paint, which is sometimes patinated with dust, shoe-paste and/or soot. Bolz discussed the intention, genesis, history and integrity of the paintings made by the artist himself compared to today’s practicing artists. She also addressed issues of authenticity and forgery.

Caroline von Courten: The Photographic Surface as Interface in mixed-media photo-works: Layers of materials, processes and meanings in Ger van Elk’s Dutch Grey, 1983/84

Unfortunately Caroline von Courten’s presentation on Ger van Elk’s painted silver-gelatin print Dutch Grey (1983-84) had to be canceled. However, in the abstract she discusses signs of the print’s early degradation. The painted surface of the print has changed due to the unintended migration of silver particles. Based on this case study, von Courten shows, “how the changing photographic surface becomes the visible juncture between what is usually separated as immaterial image and physical image carrier”. (Quote from Caroline von Courten’s abstract in conference booklet)

Caroline von Courten: The Photographic Surface as Interface in mixed-media photo-works – Layers of materials, processes and meanings in Ger van Elk’s Dutch Grey, 1983/84

Prof. Dr. Dietmar Ruebel: Handarbeit und Maschinenaesthektik – Oberflaechen als Arbeitsspeicher in der Kunst des 20. und 21. Jahrhunderts
Prof. Dr. Dietmar Ruebel: Handcraft and machine aesthetic – surfaces as internal memory of 20th and 21st century art

In Prof. Dr. Dietmar Ruebel’s absence, a colleague read his talk about handcraft and machine aesthetic – surface as internal memory of 20th and 21st century art, to the audience. In his paper he illustrated tool marks found on surfaces of mainly three-dimensional objects.

Further reading: Dietmar Ruebel, Handarbeit und Maschinenaesthektik. Oberflaechen als Arbeitsspeicher in der Kunst des 20. und 21. Jahrhunderts, in: VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 2, 2016, pp. 88-95.

Helena Ernst: “The Keep” von Mike Kelley im Museum Brandhorst
Helena Ernst: The Keep by Mike Kelley at the Museum Brandhorst, Munich, Germany

Helena Ernst presented her research and treatment on Mike Kelley’s The Keep, now in the collection of the Museum Brandhorst. Kelley’s use of various materials and especially their condition when he completed a piece requires new conservation approaches to preserve both the intention and appearance of the object. Based on the battered door of this installation, Ernst explained what condition issues she had to deal with prior to the treatment. The issue of flaking and lifting paint on the battered door was even more complicated as Kelley intended and expected visitors to come close to the door, even touch it and look through a fish eye to experience the installation. In her talk Ernst also showed how the appearance of the door was probably more important than the door itself and how even material losses are intentional. However, conservators and curators discussed how much loss is acceptable and how much loss is preventable, to support the artist’s intention. Ernst described various consolidation methods, such as insertion of pieces of coated Japanese paper that functioned as a hinge for flaking paint. This method enabled the consolidation of flaking paint without loosing the character of a battered and flaky surface.

Further reading: Helena Ernst: The Keep von Mike Kelley im Museum Brandhorst. Die Sicherung der Farbschicht: eine konservatorische Herausforderung, VDR Beitraege zur Erhaltung von Kunst- und Kulturgut, Vol. 1, 2017, pp. 35-44.

45th Annual Meeting – Workshops, May 28-29, “Reading Between the Lines: Understanding Construction and Exhibit Design Drawings” – Collections Care Network

I participated in the “Reading Between the Lines: Understanding Construction and Exhibit Design Drawings” workshop along with 12 other conservators. During the introductions, we learned that the participants come from all over the country and as far away as Taiwan and Australia. Many had signed up in order to prepare ourselves for upcoming major renovations or new construction in our institutions. The workshop was taught by four instructors: Jeff Hirsh (Architect, Principal, Director of Cultural Practice at EwingCole), Bill Jarema (Principal, Mechanical Engineer at EwingCole), Angela Matchica (Principal, Electrical Engineer and Lighting Designer at EwingCole), and Mike Lawrence (Chief of Design at the Smithsonian National Museum of Natural History). EwingCole, an architecture, engineering, interior design, and planning firm, has worked extensively with museums and other cultural and research institutions. They recently collaborated with Mike Lawrence and Cathy Hawks (Museum Conservator at the NMNH and a participant and organizer of this workshop) on building the Q?rius Learning Space at the Smithsonian National Museum of Natural History, a permanent exhibition space in which visitors can engage with the museum collections through hands-on interactions. Much of the materials that were used in the workshop – drawings, specs, images, and group exercises – are documents from the Q?rius project.

The workshop covered a lot of ground, filling two full days during which we plunged into the complex world of construction projects. The workshop utilized a mixture of powerpoint presentations, tabletop exercises, and both planned and impromptu Q&A sessions to guide us through each step of the renovation process and help us to understand different types of construction and exhibit design documentation.

Day 1: Introduction to stakeholders, phases of design, basic terminology, reading mechanical and electrical drawings

We began with an overview of the stakeholders in a given construction project and the progression of projects from start to finish. I found it very helpful to learn about the types of documentation created during the various phases of planning and what level of detail can be expected from each phase. For example, a project starts from a concept report, which narrates the scope, timeline, and intent, progress to schematic designs, then to more detailed design development drawings, and finally to construction documents, which will go out to contractors for bidding. This lesson was supplemented by a tabletop exercise that asked the participants to find light temperature information among documentation from various phases of Q?rius design process. The exercise helped to drive home the importance of becoming a stakeholder and communicating preservation priorities at an early stage of the project, since it is becomes increasingly more costly and difficult to make revisions as the project progresses.

In the morning, we also learned basic terminology and symbols found in drawings. Because depicting the numerous things that are happening in a space – both inside and outside of the walls – is so complex, multiple drawings representing various levels of detail, multiple perspectives (elevation, plan, section), and specific categories of information are necessary. These drawings are supplemented by written documentations such as indices, keynotes, and specifications to convey the full scope of information. A reviewer must understand the system of symbols used as shorthand to indicate important information such as past edits, recent changes, the location of detail drawings, and demarcations of areas slated for demolition. At the start of the workshop, Jeff Hirsch had introduced the building as “a tool for preventive conservation”, and as the session progressed, I found it increasingly more helpful to think of the drawings as a set of instructions for using a very complex tool – in our case we are looking for ways to maximize the building’s ability to support collections preservation.

In the afternoon, we delved deeper into the different types of construction drawings by examining the general, architectural, mechanical, and electrical drawings, which each come with their own system of symbols that are used to communicate a wealth of meaning. Despite the sometimes daunting complexity of the drawings, it became clear that they follow a very specific and consistent order. I learned that when reviewing the drawings, it helps to understand them as both a set of instructions for the contractors and a legally binding contract for all stakeholders. As the latter, edits and revisions are closely tracked from version to version. Successful drawings clearly, thoroughly, and accurately communicate the scope of the project, including what is being demolished, what is being built, and what materials are being used for construction. Since each drawing can contain an overwhelming amount of information, approaching them with specific questions in mind makes them easier to navigate.

Some examples of information a conservator may need include: Do the edges of a demolition space impinge on existing collections? What are the fire ratings of the partitions slated for use in collections storage spaces, and will the fire rated partitions be fully enclosed (they must be in order to be successful)? Are there flammable materials sharing a wall with collections storage? Are smoke detectors and sprinklers located in appropriate areas? Are there enough outlets reserved for housekeeping, and are they readily accessible? What types of light sources are being used and how will they be controlled? If a new HVAC system is being installed, look to the mechanical schedules for the system’s ability to provide humidification/dehumidification and filtration information, and to the control chart for set points. Finally, with all systems that require maintenance and upkeep, it’s important to consider their proximity to collections materials, the frequency of maintenance, as well as space needs of associated personnel and equipment.

Day two: preventive conservation, exhibition design, and Q&A session

On day two, instructors began with an example in which the design team and conservators collaborated to identify an optimal pathway to move collections between the freight elevator and the Q?rius exhibit at the Smithsonian NMNH. An ideal pathway was not available, so the team mapped various options on the floor plan and used color coding to identify areas with issues such as security, access, and cleanliness. The drawing was supplemented by a filmed walk through of the actual path, which communicated potential issues with a clarity and immediacy that was difficult to convey through other media. I liked the way this example underscored the ways in which preventive conservation often relies on collaboration among parties with specializations beyond conservation, and that it focussed on an aspect of the environment – pathways – that is often overlooked when thinking about preventive conservation.

This followed with a tabletop exercise to find the outlets in the the drawings for the Q?rius space, which drove home how sometimes the little things can make a big impact on the maintenance of a finished space. In this case, it was important for us to consider the amount and location of outlets designated for a new space to make sure that enough are available for both display cases and for housekeeping use. In addition, we had to consider the accessibility of outlets for housekeeping and deduce from the drawings whether staff had to crawl into the base of display cases to reach outlets, for example. Through this exercise, we also learned that it was often necessary to switch between different sets of drawings (in this case, between electrical and exhibitions) because the information we needed was covered by overlapping specializations.

Moving further into the world of exhibition design drawings, we examined ways in which an existing space can be slightly modified to provide better climate collections objects. For example, Mike discussed an instance in which he built a vestibule as a means of limiting air exchange to an exhibit space that is located close to exterior walls and windows. In these instances the contractor schedule would be the place to look for information regarding the types of doors that are designated for use in a space.

Mike also walked us through the ins and outs of looking at drawings of custom exhibit cases, which provide detailed information on what can and cannot be done. I took a lot of notes here of factors that are important in the final product, such as: glass size (may be swapped to a different type without notice), acceptable deflection amount, potential need for levelers, desiccant chamber capacity (consider the climate of space that the case is going into), presence/type of lighting inside the cases, type of gasket used (does it actually press against the other side?), presence and composition of adhesives inside case. Getting custom cases sounded like a taxing process that was further complicated by the case builder’s use of proprietary materials.

The workshop concluded with a lively Q&A session that was populated by both questions that were pre-submitted by participants and by impromptu questions. Instructors and participants discussed questions relating to fire coding in collections and user spaces, condensation in air diffusers, preparing for a new building to be added to a museum, and considering the efficacy of using inhouse vs. outside consultants on construction projects. All in all, the workshop covered a lot of ground in two day period and offered a wealth of information that I was happy to bring back to share with my colleagues in preparation for our own renovations. I certainly felt more prepared and informed when our own construction drawings arrived at my desk several weeks later.

45th Annual Meeting – Sustainability, Wednesday May 31, 2017, “With Room to Grow: Design and construction of a new conservation facility at the University of Washington Libraries”, Justin P. Johnson

Having a new conservation space built is the greatest hope and fear of many conservators – such an opportunity to take advantage of, and also to potentially go wrong! Justin Johnson’s presentation about their experiences at the University of Washington Libraries in Seattle, WA was a great insight into the process, and, given they seem to largely be pleased with the outcome, demonstrates that you sometimes can get what you want, as well as what you need.

The previous conservation space was located in a basement, cramped at only 2000 sq ft, and had last been updated in 1963. A new conservation position, partly funded by the Andrew W. Mellon foundation, was the impetus to create a new conservation space with more up-to-date equipment and space for the now four full time conservators, plus up to three part-time students and interns.

One of the early things the conservation team did was to create future goals for their space. Some of these included:

  • increasing the ability to undertake major treatments on collection items, while maintaining general collection work
  • incorporate book, paper and photograph treatments in the same space
  • have the ability to teach and train student conservators and interns
  • have a flexible and open space that could be used for workshops and research as well as treatment

The team also consulted widely with conservation scientists and treatment conservators of many disciplines.
A new space on the rooftop was identified, double the size of the previous space at 4000 sq ft, with natural light from five skylights. However, there were limitations on HVAC and ducting placement for a fume hood. Services with restrictions were placed in the design first, with other equipment fitted in around them. The fume hood location was determined first, followed by the rest of the wet lab: sinks, exhaust trunks, microscopy, suction and humidification, light bleaching and materials storage.

A multi-purpose documentation room was designed, where curtains could screen off an area to allow for photography or artefact examination and low-tech analysis, but still allow the space to be open to the rest of the lab area.

At one end of the main space a storage, office and reception area was located, with the rest of the space being fitted out for the main treatment work, including space for 10 work benches and more storage. This space had an open focus to encourage communication and collaboration as well as reconfiguration, when required.

While an architectural team was engaged to create the space, the conservation team were heavily involved, thinking through the design of furniture (especially for storage purposes) and thoroughly investigating the departmental work flows and how they would work in the space.

The conservation team drew their workflow movements on paper and overlaid them on the design drawings and also used computer tools, such as Live Home 3D Pro, to visualise the space and move furniture around to try out new orientations. This software was very useful to ‘walk through’ the space, make adjustments to the design and then send them via pdf to the architects. It also facilitated communication between the conservators and architects and saved a lot of money in lengthy redesigns which would have occurred in a later phase of the project.

15 months after the initial bid phase, the team moved into their new space in February 2016.


Q1) What is the climate and do you know the air exchange rate? A1) Aiming for 70F/50% but are still in the process of balancing the AHUs. They are finding that the fume hood competes with the HVAC.

Q2) Who did the lighting design? A2) It was done by a UWA group at the end of the project; the Live Home 3D Pro software has a large database of furniture and lighting which can be added to the design.

Q3) What was the total budget? A3) Got support from the Mellon grant, UWA donors and campus funding. A lot of money was saved in design fees by the proactive work of the conservation team.

Q4) What was the size of the benches and the area around them? A4) The benches both fixed and moveable are all the same height and measure 60” x 38” with 3.5’ between benches.

Q5) Detail on the skylights: specification and R values? A5) The lighting system has an automated system to take the daylight into account; the lights reduce on a bright day (which is rare in Seattle!).

45th Annual Meeting – Objects Session, Wednesday 31 May 2017, “So Delicate, yet So Strong and Versatile: The Use of Paper in Objects Conservation” presented by Paula Artal-Isbrand

Paula Artal-Isbrand, Objects Conservator at the Worcester Art Museum, presented the various ways in which she uses paper in her objects treatments. She shared some background on paper types. Asian papers typically come from the paper mulberry tree and produce long fibers (kozo) and strong paper or from the gampi tree, producing shorter fibers to make crisp and translucent papers. Mitsumata shrubs are a third source, but not part of this presentation. Western papers are more often made from cotton, linen, flax, or hemp. Paper in conservation is strong, inert, compatible with conservation materials, has excellent long-term stability, and does not pose health risks. It can also be manipulated to mimic a wide range of materials through inpainting and coating. By choosing the right coating materials, the translucency and texture can be adjusted to fit the application. These papers can also be inpainted with standard inpainting materials to match color and texture.

Beaker, Roman, 3-5th century CE, glass, 15.5 x 7.0 x 6.5 cm. Sardis archaeological site (Turkey), Inv. # AhT67.IV.130N3,before and during treatment using kozo paper saturated with B-72 acrylic consolidant (Courtesy of Sardis Archaeological Excavation, photo: Paula Artal-Isbrand)

Artal-Isbrand outlined two ways for thinking about how to use paper. First, it can be used as a restoration material. Artal-Isbrand offered several examples of how she’s used paper in this way. For example, she used acid-free matboard cut into shape for a loss repair in a fan. For archaeological glass, she toned paper kozo paper with watercolors (not with acrylics since they would create too much opacity) and impregnated the paper with Paraloid B-72, acrylic co-polymer. The toned and resin soaked fill was a perfect match for the glass and was attached with Paraloid B-72. She has made paper fills to reconstruct chain mail, for joining heavy elements of an iron helmet, for reinforcing failing solder joins for bronze armor, and for backing a Roman lead curse tablet that needed to be unrolled. These repairs were carried out using a combination of kozo paper with Paraloid B-72, and are a testament to the paper’s strength. Artal-Isbrand also described that paper can be an interlayer between an artifact and fill material to ensure reversibility and how cellulose powder can be a bulking additive for fills, and if toasted, can also impart pigment to fills.

Missyurka turban helmet, Ottoman Empire or Caucasus, 16th century, iron, 29 x 18 x 18 cm. Worcester Art Museum, 2014.102. Bequest of John A. Higgins, during and after treatment with kozo paper strips. (Courtesy of Paula Artal-Isbrand)
Missyurka turban helmet, Ottoman Empire or Caucasus, 16th century, iron, 29 x 18 x 18 cm. Worcester Art Museum, 2014.102. Bequest of John A. Higgins, before, during (using kozo paper band-aids) and after treatment. (Courtesy of Paula Artal-Isbrand)

Second, paper can also be used as a tool. It can work well as a facing for an intermediate phase of treatment. It can also serve as a barrier layer. For example, thin papers are a great barrier film for gels. Here, Artal-Isbrand mentioned that thin gampi paper can be good for this. The paper is placed between the surface and the gel, allowing for easier clean up in gel removal. Paper can be a poultice material. Artal-Isbrand uses Whatman cellulose powder, which will cling well and hold the poultice solvent. For these same reasons, shredded filter paper soaked and blended in water can be used to create a mold of another artifact. The mold should be sealed with resin (for example, Paraloid B-72) to keep it from getting damaged by water applications. If using the mold for creating a plaster fill, this step is critical.


During the question / answer period, there was a brief discussion on how shredded paper serves well for poulticing, and is better than cellulose powder or other very fine materials, because those become difficult to remove and can leave a hazy residue. So, it is important to distinguish between powder and pulp or shredded and/or ground paper. An interleaving layer can be helpful if powder is used. Also during the discussion, another example was mentioned that paper can be rolled into “worms,” impregnated with Paraloid B-72, and inserted it into losses to provide filling that is more easily removed than putties or other fillers.

C2CC May Webinars: Deaccessioning and Outdoor Sculpture

May 17, 2017, 2:00 – 3:30 EDT Legal Issues in Collections Management with ARCS

Why do we need this? Insights and Hindsights from Deaccessioning

Sign up:

Join Leslie B. Jones to discuss the multiple steps, and back-steps, of deaccessioning a diverse selection of objects from a collection using the experience of the 2014 to 2017 Cheekwood Permanent Collection deaccession initiative. Topics covered include assessing previous institutional deaccessions, board review and approval, collecting plan development, cross-reference of digital and hard files, institutional transfers, ethnographic materials and indigenous organizations, and donor relations.

May 23, 2017, 2:00 – 3:30 EDT

Inside Out: The Inside Scoop on Your Outdoor Sculpture

Sign up:

Are you responsible for carrying out the preservation of outdoor sculpture at your institution or business? Join Joanie Bottkol, Karen Fix, and Margaret Breuker, conservators with the National Park Service, for a webinar about the maintenance of outdoor sculpture: the whys and wherefores, what you can do on your own, and when you might need outside help.

IIC 2018 Congress in Turin: Call for papers and posters (extended deadline)

IIC 2018 Congress
Preventive Conservation: The State of the Art, Turin, 10 – 14 September 2018
Simultaneous call for papers and posters

  • Closing date extended to June 5, 2017

Preventive conservation is a vital and ever-developing field at the centre of museum, site and heritage management, contributing to the sustainability of organisations as well as to the care of their collections. An IIC Congress last addressed issues in preventive conservation in Ottawa in 1994 and much has changed since then: new methods of investigation and analysis; a greater understanding of materials and how they may change or decay with time; developments in conservation practice. For conservators, conservation scientists and all those concerned with preventive conservation there are still as many questions as answers, still matters of concern to be discussed; many of you working in the field have something to say and exciting research to bring to us. To enable you to do this, we have extended the closing date for the call for papers and posters to 5 June 2017!

It will be 24 years since an IIC Congress last specifically addressed issues in preventive conservation, in Ottawa in 1994. The field has developed enormously since 1994: preventive conservation has a central position in museum, site, and heritage management. In addition to capturing developments and changes in scientific understanding and practice, this congress will focus on current issues that exercise our field and will look to the future. It will build on some recent IIC initiatives, including the 2008 Congress on Conservation and Access and the IIC/ICOM-CC environmental guidelines developed at the 2014 Hong Kong Congress.

The location for the 2018 Congress is Turin, a city with a varied cultural history, a strong international profile and innovative industrial centre and, at the same time, a comfortable, relaxed ambience. We are delighted that our partners in the 2018 Congress are the City of Turin, the Italian Regional Group of IIC (IGIIC), Turismo Torino e Provincia and the Centro per la Conservazione ed il Restauro “La Venaria Reale”, which, most appropriately, is housed in one of the Savoy palaces, La Venaria Reale.

Please don’t delay! We now invite paper and poster proposals that address the issues defining the state of the art in preventive conservation and latest practice. A full list of suggested topics and themes and full details for submission can be found at the main IIC Congress web-site page here:

Please note that this is a simultaneous call for paper and poster proposals: there will be no later separate call for posters. IIC invites you to submit your proposal for a paper or poster in English in about 500 words (3500 characters) via the website here: If you have an IIC account, please log in first; if not, please register on the front page of the site for an IIC account before submitting a proposal. Please do not include any illustrations with your proposal submission and please indicate if your proposal is for a paper or for a poster. The deadline for the receipt of proposals has been extended from May 8 to June 5, 2017.

We look forward to seeing you in Turin!

C2CC Legal Issues Webinar Series, April & May

Connecting to Collections Care is pleased to offer a special series of webinars on Legal Issues in Collections Management.  For this series, C2CC partners with ARCS, the Association for Registrars and Collections Specialists. Join us!

April 12, 2017 Introduction to Legal Issues in Collections Management with John E. Simmons

April 19, 2017 Ethical Issues in Collections Management with Sally Yerkovich

May 17, 2017 Why Do We Need This? Insights and Hindsights from Deaccessioning with Leslie B. Jones

All webinars are scheduled from 2:00 – 3:00 EDT and they are free. Check our website to sign-up: We hope to see you there.


Scholarship – SOIMA 2017: Sustaining Sound and Image Collections

The International Centre for the Study of the Preservation and Restoration of Cultural Property (ICCROM), and the Institute of African Studies at the University of Ghana are pleased to announce its 2017 SOIMA International Course on Sustaining Sound and Image Collections in Accra, Ghana, July 9 – 23, 2017.

The advanced workshop is tailored to address the challenges of collecting, preserving and using (and reusing) sound, still, and moving image content within the broader context of rapidly changing technology and shrinking resources. It will focus on collection management issues in different institutional contexts that are unique to these types of materials.

The course will include topics such as: digital preservation, collection assessments, dealing with digitization and documentation backlogs, utilizing innovative open access solutions, intellectual property rights, copyright legislation, community-based archiving and assessing values and meanings of audiovisual collections.

The program will be designed according to participants’ current and future projects. It is a unique opportunity for professional development and expanding your network. A limited number of scholarships will be given, but only after the due selection process and upon providing evidence on lack of support.

Applicants should send their completed application form with a completed personal statement by April 3 to

The application form is available at:

For further information, visit:

Workshop Recap: Nanotechnologies for Conservation

Pratt Institute’s lovely Brooklyn campus (with Philip Grausman’s Leucantha, 1988-1993). image: Jessica Walthew


In January 2017, Sarah Nunberg (Conservator in private practice, Stockman Foundation Fellow at Pratt Institute) and Dr. Cindie Kehlet (Professor, Department of Math and Science, Pratt Institute) organized a four-day workshop on Nanotechnologies in Conservation at the Pratt Institute in Brooklyn, NY. Dr. Piero Baglioni and Dr. Rodorico Giorgi of the University of Florence Research Center for Colloids and Surface Science (CSGI) lectured on two EU-funded projects, NANOFORART and  NANORESTART. The workshop focused on three of the technologies CSGI developed for conservation of cultural heritage: gels, microemulsions, and nanoparticle solutions. Conservators specializing in varied disciplines  from institutions and private practices on the east coast attended the workshop.

CSGI has developed materials to address consolidation, cleaning and deacidification problems identified by colleagues in conservation, and continues to consult and collaborate internationally on a wide range of conservation projects. They have developed conservation products for cleaning and consolidation using nanotechnologies.[1]


Conservators in all specialities have adopted the use of gels and thickeners for controlled cleaning of artworks. In the United States, over the past decades Richard Wolbers and Chris Stavroudis (among others) have introduced and popularized viscosity modifiers made of natural or synthetic polymers (e.g. Xanthan gum, Pemulen, Klucel, Carbopol, Velvesil plus). These materials allow conservators more options for tailoring cleaning solutions and restricting penetration into porous substrates. [2] Viscous solutions can limit solvent volatility, increase contact time, and combine immiscible solvents to form stabilized emulsions.  More recently, physical gels made of polysaccharides (e.g. agar, gellan) have been used as “containers” for aqueous and some solvent cleaning applications.

Testing nanogels with water for removing Wolbers’ artificial dirt applied to a painted surface mockup “Pollock.” image: Jessica Walthew


While a variety of gels and thickeners have been readily adopted for use in treatment, concerns remain about controlling their application (e.g. conforming to different surfaces), specifying pore size, controlling solvent release and eliminating residues. Gels made of crosslinked polymers in semi-interpenetrating networks – such as those developed and introduced by CSGI – offer new options in the conservator’s toolkit.  Imaging and analysis conducted by Baglioni and others has worked to identify and localize residues, and confirmed that the hydrogels and organogels do not leave a residue due to their structural and physiochemical properties.[3]

At the workshop we worked with two types of CSGI hydrogels: chemical gels made of poly(2-hydroxyethyl methacrylate) (pHEMA)/ polyvinylpyrrolidone (PVP) formed by covalent bonds and physical gels made of polyvinyl alcohol (PVA)/ polyvinylpyrrolidone (PVP) or PVA/PVA formed with secondary bonds (dispersion forces or hydrogen bonds).[4] Hydrogels are compatible with aqueous cleaning solutions, some polar solvents, and microemulsions (i.e. oil-in-water). CSGI’s chemical hydrogels are rigid, clear sheets that are cut to the size of the area treated. The physical gels are similar to Jello in consistency and texture, but clear and colorless. Another class of gels being developed by CSGI, organogels, open up a wider variety of solvent options. [5] Depending on the desired characteristics, these gels can be engineered to have different properties (e.g. elasticity, solvent retention, solvent compatibility) based on the polymers used, synthesis procedures, and degree of crosslinking.


Conservators often remove natural and synthetic adhesives and coatings from fine art surfaces by solubilizing the unwanted material. Solubilization risks incomplete removal, penetration into the substrate (especially if the substrate is porous), leaching out original materials, redeposition, and tidelines. Moreover, solubilization and removal of material must often be accompanied by mechanical action, which can damage sensitive underlying surfaces. Additionally, solubilization of aged coatings with neat volatile organic solvents often requires the use of polar, aromatic, or otherwise aggressive solvents that pose risks to the environment and human health.

Three of the Nanorestore microemulsion products available from CSGI. image: Jessica Walthew


Microemulsions are made from a micellar solution (a dispersion of surfactants formed when the concentration of surfactant exceeds a threshold value called the critical micellar concentration), in which a surfactant is used to contain a dispersed phase in a continuous phase (either water-in-oil or oil-in-water). Stable microemulsions can be extremely effective at cleaning because of the exponential increase in interphase surface area, where the cleaning activity occurs. As a result, smaller amounts of solvents are needed for highly effective cleaning solutions. Other microemulsion formulations have already been used in conservation for cleaning acrylic painted surfaces and plastics, as developed by Dow Chemical/Getty Conservation Institute/Tate. [6]

Several of the nanostructured solutions developed by CSGI can also work through dewetting (the opposite of surface wetting) instead of solubilization. In dewetting, the microemulsion activates and swells the polymer coating, forming a discrete layer that can be removed.  Minimal mechanical action with a dry swab rolls off the swelled, dewetted polymer.

Acrylic overpaint removed from a test painting with a microemulsion demonstrating the dewetting mechanism. image: Cindie Kehlet


The CSGI microemulsions were initially developed for conservators working on wall paintings in Italy and Mexico that were deteriorating owing to aged acrylic and polyvinyl acetate coatings. The microemulsions can be used for removing synthetic polymers such as coatings or graffiti, but must be tested carefully for each application. Careful formulation is crucial: therefore it is important for conservators to work closely with CSGI to understand the product components and devise the best systems for their treatments.   

As for the gels and viscosity modifiers described above, residues left behind from cleaning agents have been a major concern for those considering using emulsions and microemulsions for cleaning painted surfaces and plastics. For emulsions, high proportions of surfactants are sometimes needed to stabilize mixtures, and surfactant residues may attract dirt to the surface, or change surface gloss. Going forward CSGI and their research partners aim to identify self-degrading surfactants (that decompose without leaving a residue) for use in future conservation products. CSGI is also working to limit the amount of toxic solvents (such as methyl ethyl ketone) used in their microemulsions.

Dr. Giorgi showing a painting with test cleanings performed with gels and areas to test removal of acrylic overpaint. image: Jessica Walthew



Nanoparticles (0.1-0.2 um in size) in suspension can be used for a variety of applications where penetration into surfaces is desirable. The main applications of nanoparticle solutions in  conservation are for consolidating carbonate materials (i.e. stones or frescoes) and deacidifying paper and canvas. Nanoparticles can be dispersed in alcohol to form stable solutions, called nanoconsolidants. These can be applied to stabilize surfaces in preparation for subsequent treatment steps. As an example, they can be used to pre-consolidate friable wall paintings before salt removal, as they do not interfere with subsequent treatments or mobilize soluble salts.  These treatments reproduce the original physiochemical properties of the artwork by undergoing the lime-cycle carbonation process, allowing crystals to bridge gaps as they form, effectively reconstituting the same binder as the original paint (inorganic CaCO3). Another application is to counteract and prevent acid hydrolysis in cellulosic materials: spraying Ca(OH)2 particles onto paper or canvas can effectively adjust and neutralize the material’s pH. [7]

Workshop participants experimenting with nanomaterials. Pictured: Cathy Silverman, Fellow in Objects Conservation at the Metropolitan Museum of Art. image: Jessica Walthew


After learning about the chemistry and principles behind these materials through Dr.Baglioni and Dr. Giorgi’s lectures, workshop participants experimented using a variety of mock-ups and artworks. We tested aqueous cleaning of paper and painted surfaces with the highly retentive chemical gels, microemulsions applied with cotton poultices and/or hydrogels for the removal of coatings on terracotta and fresco surfaces, and removal of acrylic paint covering oil paint, as well as applying solutions of Ca(OH)2 nanoparticles for fresco consolidation. As always, each conservator needs to develop a sense of the working properties of any tool or material to see how they will be useful. Dr Baglioni and Dr. Giorgi admirably contextualized the need for these materials, the underlying chemistry and physics, and the particular benefits these nanotechnologies provide.

The final day of the workshop focused on a project investigating the materials and restoration history of a Louise Nevelson painted wooden sculptural installation at St. Peter’s Church in Manhattan. A variety of treatment options were considered and tested, including chemical gels. Sarah Nunberg will present on this project at AIC:“Treatment of a White Louise Nevelson Installation” in the General Session, You Can’t Go It Alone.[8]

Sarah Nunberg discussing the cleaning treatment of a sculptural environment by Louise Nevelson in the Chapel of the Good Shepherd at St. Peter’s Church. images: Jessica Walthew


Overall, the workshop was an extremely well-organized and exciting introduction to the vast applications of nanotechnologies in conservation. Dr. Baglioni, Dr. Giorgi, and their colleagues have published widely on their research, see the CSGI site for more information and selected references.

Thanks very much to Dr. Baglioni, Dr. Giorgi, the organizers, Pratt Institute, and the other participants for a wonderful and stimulating few days. Keep an eye out for the upcoming WAAC newsletter, which will feature a discussion of the practical use of these technologies.

[1] These materials are available for low cost directly from the University of Florence, per the arrangements of the EU funding source supporting this research: see the CSGI website ( Reducing the environmental and human health impact is an important goal of CSGI’s projects. For an overview, see Giorgi, Rodorico, Michele Baglioni, Debora Berti, and Piero Baglioni. “New Methodologies for the Conservation of Cultural Heritage: Micellar Solutions, Microemulsions, and Hydroxide Nanoparticles.” Accounts of Chemical Research 43, no. 6 (June 15, 2010): 695–704. doi:10.1021/ar900193h.

[2] See the Conservation Wiki “Gels, Thickeners, and Viscosity modifiers” bibliography 

[3] This was a key concern during development of these products and was tested with a variety of analytical techniques e.g. Focal plane array FTIR. See Domingues, Joana A. L., Nicole Bonelli, Rodorico Giorgi, Emiliano Fratini, Florence Gorel, and Piero Baglioni. “Innovative Hydrogels Based on Semi-Interpenetrating p(HEMA)/PVP Networks for the Cleaning of Water-Sensitive Cultural Heritage Artifacts.” Langmuir 29, no. 8 (February 26, 2013): 2746–55. doi:10.1021/la3048664.

[4] While these may seem unfamiliar to you at first glance, interpenetrating network polymeric gels are the same kind of technology used for making soft contact lenses.

[5] Organogels are described in greater detail in Baglioni, P. et al. 2015. Organogel formulations for the cleaning of easel paintings. Applied Physics A 121 (3): 857–868. doi:10.1007/s00339-015-9364-0 and Piero Baglioni, David Chelazzi, and Rodorico Giorgi. Nanotechnologies in the Conservation of Cultural Heritage: A compendium of materials and techniques. Springer Netherlands. 2015. DOI 10.1007/978-94-017-9303-2

[6] See “Mineral Spirits-Based Microemulsions: A Novel Cleaning System for Painted Surfaces” Bronwyn Ormsby, Melinda Keefe, Alan Phenix, Eleanor von Aderkas, Tom Learner, Christopher Tucker, and Christopher Kozak, Journal Of The American Institute For Conservation Vol. 55 , Iss. 1, 2016. Note that for all microemulsions, the phase diagrams describing stable formulations can be complex, and it is difficult to formulate these in most museum labs.

[7] See Giorgi et al. 2010 (full citation in reference 1)

[8] This work will also be presented  at the 2017 Gels in Conservation Conference in London. (Nunberg, S. C. Kehlet, S. Alcala, C. Tomkiewicz, C. McGlinchy, M. Henry, J. Dittmer. “Conservation of a White Louise Nevelson Installation: Gel Systems Explored”) and has been submitted for review for the 18th Triennial ICOM-CC Conference in Copenhagen: Nunberg, S., C. Kehlet, S. Alcala, C. Tomkiewicz, C. McGlinchy, M. Henry, J. Dittmer. 2017. Conservation of a White Louise Nevelson Installation: Treatment Choices Based on Ethical Discussions and Analytical Studies.

C2CC Webinar 3/16: Oversize, Overwhelmed? Caring for Maps and Architectural Drawings in Your Collections

Do you have maps and other very large archives materials that you don’t know how to handle and store? Join us for Oversize, Overwhelmed? Caring for Maps and Architectural Drawings in Your Collection March 16th, 2:00 – 3:30 EDT. It’s free!

Oversize, overwhelmed? Caring for Maps and Architectural Drawings in Your Collection