Not often does one read about the use of reptiles in art conservation. Interest immediately spikes with the word gecko, that warm climate lizard that you often cross paths with during your much-needed tropical vacation.
In our efforts to find novel and non-destructive methods to clean artwork, conservators and conservation researchers set about to find applications in corollary fields that might be adapted to our needs. During this PSG presentation on the Tuesday, Cynthia Schwarz presented the work being conducted alongside fellow contributors Hadi Izadi and Kyle Vanderlick, Cynthia stressed from the outset that this was a very early pilot study, but the depth of information would suggest that quite a bit of work has already been initiated. This work focused on the generation of a new cleaning tool that mimicked the unusual adhesion principles found in the tiny (no, really tiny) toe pads of geckos. This cleaning tool is called a μ-Duster, which is composed of PDMS (polydimethyl siloxane) fibrillary microstructures that are able to remove particulates from vulnerable surfaces.
Geckos have the ability to climb, adhere and release from just about any surface, and can remarkably unclog dirt that lodges in the toe pad structure simply by taking a few more steps atop your beachside resort table lamp. The primary mechanism for adhesion are van der Waals forces, which Izadi modified in the application to create a gecko-mimicking material. Like gecko pads, the goal was to create a dry technology that left no residues, left no mechanical damage and only required minimal force to use. The necessity of such a cleaning tool is high: conservators are confronted more and more with surfaces that are sensitive to liquids (aqueous and solvent-based), complex in nature (such as acrylic paint) and cannot tolerate the presence of any residues in the short or long term (absorbent surfaces). Gecko-inspired adhesive tapes are in use, so why not an adaptation as a cleaning tool?
In the testing, the micro-pillar cleaning tool touches the test surface in a dab and pinch method. Test surfaces were made to mimic an acrylic paint surface, which was composed of poly(methyl methacrylate) (PMMA) as well as actual artificially soiled acrylic paint films. Note that the soiling agents were a variety of silica spheres and that the team tested three different pillar sizes. Colorimetry, gloss measurements and SEM imaging monitored the test surfaces before and after testing. Tested alongside the μ-Dusters were other dry methods such as goat hair brushing and polyurethane cosmetic sponges. The results suggest that the μ-Dusters are able to not only remove loosely bound contaminants, but also sub-micrometric particles that were not removed by other methods such as traditional dusting methods. Concurrently it was revealed that the damage to the surface from the process was noticeable with cosmetic sponge and brush-dusting evidenced in lateral marks seen via SEM imaging, while the much gentler μ-Duster cleaned areas avoided said damage.
This initial foray into μ-Duster cleaning of vulnerable surfaces is very promising, and the researchers note that many factors will come into play during development. The challenges presented by this method include a learning curve (it isn’t a very intuitive method … one has to practice the technique), the roughness of the surface (with some resolution by creating a thinner backing for the μ-Dusters), the slowness of the activity, the repeated contact with the surface and the necessity of cleaning the μ-Dusters (possible need for solvents in the cleaning and re-use of the μ-Dusters). Future research includes methodologies that necessitate cleaning with progressively smaller sizes of pillars (analogous to sanding wood with finer grades of sandpaper), development of different tip shapes for a wider range of dust particle sizes, creating a roller/brayer type tool (which may not be ideal for paintings) and micro-structuring solid gels for cleaning. Cynthia revealed an exciting prospect in nanometric particle removal … this might include soiling agents such as tobacco smoke (goodbye wet cleaning) and an application of removing particles out of air bubbles trapped in the matrix of acrylic paintings.
Thanks to Cynthia and her colleagues for crafting a presentation that was derived from a topic replete with many physics and chemistry based components. I endeavored to draft this blog as an attendee that hails from the bench, and any errors in my interpretation are completely my own. I very much look forward to the growth of this new non-destructive cleaning model.