Topics in Photographic Preservation 1988, Volume 2, Article 5 (pp. 40-49)
Three French Photograph Conservation Techniques
by Nora Kennedy
This paper is a description and discussion of three conservation techniques used in France. These include the use of gouache en poudre (a toning method), the fond tendu (a lining method), and nettoyage à la Tylose (a mount cleaning method).
My graduate internship for the Winterthur Museum/University of Delaware Art Conservation Program was spent in Paris, France. The year was divided between the Atelier de Restauration de Photographies under the supervision of Anne Cartier-Bresson, and the Centre de Recherches sur la Conservation des Documents Graphiques under Françoise Flieder and Martine Gillet. The techniques described were learned at the Atelier from Anne Cartier-Bresson, and from Claude Laroque and Florence Herrenschmidt, private paper conservators in Paris.
The Atelier de Restauration de Photographies is responsible for the care of the photographs in the collections of the City of Paris. These include the Bibliothèque Historique de la Ville de Paris, the Bibliothèque Administratif, the Bibliothèque Marguerite Durand, the Musée Carnavalet (which also provides laboratory space for the Atelier) and a number of other libraries and museums under the city's juristiction. The photographic holdings of these institutions are considerable and impressive.
Gouache En Poudre: A Method for Toning Inserts
In France, gouache en poudre is a powdered pigment available from Winsor & Newton. This particular product is not available in the United States, but any good quality powdered pigment can be substituted.
- An insert paper of compatible weight and manufacture is chosen.
- Various pigments are doled out into a porcelain or glass dish, until the correct tone– or something close to it– is achieved. The pigments are mixed thoroughly.
- The mixture is transfered onto the insert paper and rubbed in with a brush or cotton swab.
- Excess pigment is removed with an air bulb, a brush or a cotton swab.
- The final tone and intensity can be adjusted by either adding more pigment, or by swabbing or erasing off the excess.
- a) The use of gouache en poudre is a very quick way of toning large inserts.
- b) The dry pigments produce a smooth application, potentially free from graininess (depending on the insert paper used).
- c) A smooth gradation of tone can be achieved in inserts where this is desirable.
- a) It is preferable to complete toning prior to insertion of the fill, engendering a certain inflexibility to the technique. Adjustments made later raise the possibility of stray pigment overflowing onto the photograph being inserted.
- b) The presence of unfixed pigment on an insert can be objectionable, because this may cause pigment transfer to interleaving papers and, ultimately, to the object. This disadvantage can be overcome through the use of an appropriate fixative. It should be noted that almost any fixative will to some extent change the intensity and tone imparted by the pigment alone. These changes can be compensated for in advance, as necessary.
- c) A warning should be noted regarding the toxicity of many pigments. Measures should be taken to minimize inhaling them.
The Fond Tendu: A Lining Method
The term fond tendu can be loosely translated as a ‘taut or tightly held base or background.’ The method described below is a variation on the fond tendu used in paper conservation in France.
At the Atelier de Restauration, the mounting or remounting of photographs onto matboard supports was avoided where possible. Objects requiring additional support due to extensive tears, losses, and/or brittleness were lined on a Japanese tissue by the fond tendu method rather than being mounted directly onto a solid support. They were subsequently hinged into a good quality mat and mount.
- A plate of glass with at least a 4–5″ margin beyond the dimensions of the photograph to be lined is cleaned thoroughly.
- A sheet of polyester film (roughly 2″ larger on every side than the photograph) is sanded evenly on one side. It is wet up, then placed with the smooth side against the glass. The film is rolled out with a rubber brayer to remove air pockets. The polyester film expedites the separation of the lined photograph from the glass after treatment.
- A piece of Japanese tissue (lightweight for albumen prints heavier for gelatin bromide prints) is cut slightly smaller than the dimensions of the glass. It is placed on the rough side of the polyester film, and is wetted up with a sponge used only for this purpose. The pattern used for wetting up (Union Jack, left to right, center out horizontally, etcetera) is chosen at the discretion of the practitioner.
- A water sensitive paper tape is put down on all four sides of the Japanese tissue, adhering it to the glass.
- The tissue is allowed to air dry until it is just barely moist.
- Methylcellulose diluted to 30 g/L is brushed onto the tissue with a wide Japanese brush. This is initially applied thickly, but is then worked into a thin, even layer.
- The surface of the lining paper must be absolutely free of imperfections. This step is the last chance to remove flaws in the paper, fallen brush hairs, bits of lint and anything that might disrupt the final surface.
- The photograph is humidified by the method preferred (humidity chamber, damp blotters, water mist, etcetera). The object should be “relaxed” enough that it will not be severely distorted when brought into contact with the adhesive, but not so wet as to interfere with adhesion.
- The photograph is transferred to the Japanese tissue on a temporary polyester film support. The polyester film is removed from the face of the photograph. All tears are aligned.
- Cockles, creases and other surface imperfections are worked out through local manipulation with a bone folder through protective tissue. At the Atelier, Japanese tissue was used to help absorb excess moisture and adhesive.
- The photograph is rolled smooth with a rubber brayer under a protective layer of Japanese tissue. The brayer is applied from the center outwards. Pressure is gradually increased to force out trapped air and excess adhesive.
- The lined photograph is allowed to air dry. Once dry, the Japanese tissue is cut away from the glass support, then trimmed to the dimensions of the photograph.
- a) The fond tendu provides an excellent ‘working surface’:
- – it holds the object flat so that inpainting or insert colors can more easily be matched;
- – it provides a portable base for workspace flexibility;
- – the support is transparent and can be used in conjunction with a light table for inserting losses, replacing brittle fragments and so on;
- – once inserted, the object will dry flat.
- b) One useful application is the lining of multi-image panoramas which are easily aligned on the fond tendu.
- a) The primary disadvantages are those inherent with any lining procedure as opposed to a mounting procedure, including:
- – curling; and
- – insufficient support.
- b) Another point of consideration is the potential amount of tension the photograph is subjected to being dried on a fixed base.
Nettoyage A La Tylose: A Mount Cleaning Method
Nettoyage à la Tylose refers to a ‘wet cleaning’ method used to remove ground-in surface grime. The French word nettoyer means “to clean”, nettoyage is the noun from the same base. Tylose (R) is a French brand name for methylcellulose.
An attitude has been developing among photograph conservators that not every mounted photograph should necessarily be unmounted and remounted. There are many cases, indeed, where it is imperative that an original mount be retained, be it for historical reasons, or for concern for saving the photograph from stress of treatment. With this in mind, this technique is useful in reducing surface grime and other accretions on original mounts that surface cleaning cannot remove. To a much lesser extent, nettoyage a la Tylose will help to flatten cockled boards.
- 1. A blotter is cut to the size of the photograph and is used to cover the image during dry and wet cleaning of the mount.
- 2. The exposed edges of the mount obverse and the full reverse are surface cleaned with an appropriate eraser material.
- 3. The image is again covered with a tailored blotter. A watery dilution of 4 g/L or 0.4% methyl cellulose is brushed out on the exposed mount with a natural bristle brush. Good quality brushes for this purpose are available from cooking supply stores in this country. The application should be from the center out, moving around the mount edges. Care should be taken not to drip excess onto the protective blotter. Smaller stiff brushes can be used on areas of ground in grime. The application of the methylcellulose can be generous, but must proceed at a quick pace to avoid excessive penetration of the liquid.
- 4. A small smooth sponge used only for this purpose is dipped in deionized water, squeezed out thoroughly, and used to wipe away the Tylose. This ‘rinsing’ step can be repeated.
- 5. The above sequence is repeated on the board verso using the Union Jack pattern for application of the Tylose, and for the ‘rinsing’ step(s). Again, speed is imperative.
- 6. The mounted photograph is placed between polyester web and blotters, and beneath plate glass and weights for drying. The blotters are changed frequently at the outset, followed by gradually increased increments of time.
- a) Nettoyage à la Tylose cleans ground in grime and other accretions from original mounts, when these cannot be removed by other cleaning methods.
- b) It can also reduce cockling in mounts by providing a light humidification prior to drying under weights.
- a) This technique is not suitable for all original mounts. Ideally, the board should be smooth and well sized. Blotter-like boards soak up moisture too rapidly, making them susceptible to damage.
- b) In all cases, the work must proceed at a quick pace to prevent moisture from penetrating too far and causing:
- – delamination of the photograph from the board;
- – delamination of layered boards;
- – migration of staining;
- – pilling on the board surface;
- – deformation resulting from variable expansion, caused by different application on obverse and reverse.
- c) Residues of methylcellulose may remain on the board surface. This can be overlooked either as negligible, or as a “resizing” of the board, depending on one's philosophical inclinations.
Conservators are usually eager to add new conservation techniques or variations on existing ones to their treatment repertoires. The three treatments presented above are to be used, discussed, and adjusted to individual habits as necessary. To help broaden our sources of information it is useful to establish avenues for international exchange with overseas conservation communities. There is much to be learned from this type of communication and collaboration. I hope that this paper adds a small segment to the international network so vital to growth in our profession.
My internship year in France was funded through the generosity of the Winterthur Program, the Getty Foundation, and the Friends of French Art. Some of the treatment slides shown during the presentation of this paper in New Orleans, February 1987 were courtesy of the Musée Carnavalet, the Bibliothèque Historique de la Ville de Paris, and the Bibliothèque Administratif. I would like to thank Anne Cartier-Bresson and Debbie Hess Norris for their support and guidance, and the many individuals in France and the United States who made the year such a rewarding experience.