Turned Out to be a Pretty Nice Day, After All
This little panel painting on board is dirty, or was dirty.
Besides completely masking the design, the colors, and the details of this picture, the surface dirt has swapped the crisp March morning for a dour November afternoon.
The dirt is not just a layer that has settled on the paint surface. It is a complex interaction of carbon, hydrogen, oxygen, nitrogen, silicon, phosphorus, proteins, salts and minerals in an ionic dance with the pigments and the resins of the painting. These elements have been trading ions for years. So any agent used to clean the dirt away, necessarily changes the chemistry of the original material. That is why a Professional Conservator will choose a cleaning agent that can capture the dirt without pulling away essential compounds of the original pigments and binders. With the return of the original design, colors, and details, comes the fresh frosty air of a March morning.
Clear Your Brow
Art Conservators are relaxing with fresher air these days. Thanks to Conservation scientists, like Chris Stavroudis and others, cleaning paint surfaces are moving away from heavy solvents to more user and environmentally friendly solutions. Chris conducted a Workshop on his Modular Cleaning Program at the St. Louis Art Museum this past month. Under an IMLS grant petitioned by the Missouri Botanical Garden and attended by many Missouri conservators, the Workshop offered a new, cleaner age of conservation.
Watt Restoration March 2017
Cleaning Soot From Painting Surface and Collateral Damage
Fireplace soot is a common yet insidious grime on the surface of an oil painting. If the painting has had a layer of varnish, removal of soot is easier. But if the varnish has aged and cracked, exposing the paint layers to the settling soot, removal is tricky.
In the example, a early 19th Century still life by Ella Sophonisba Hergesheimer, the soot is most clearly imbedded in the frame rabbet margins and the center paint damage. An aqueous solution with strong surfactant did not remove the soot satisfactorily. Besides, the layer of discolored varnish had to be removed as well. An acetone/xylene Carbopol gel worked effectively on the aged varnish, as well as the soot.
The gel was cleared with an aqueous/surfactant solution that removed residual varnish and soot. The tricky issue was that affecting the top layer of paint was unavoidable. Largely this was due to the chemical change of the surface paint layers in the years of exposure to the soot and to the air. It goes against a conservator’s conscience to jeopardize original paint, but in an effort to extend the life and aesthetic of the work, a compromise was reached.
The more vulnerable pigments, like the umbers and the lakes were cleared of the varnish and soot with the strong and quick acetone gel. As the debris indicates in the image to the right, the black soot came off, the amber/green varnish came off AND some of the top layer of damaged umber paint. The clearing left behind a canvas/ground/paint composite that could be safely consolidated and flattened. The color revived yet the overall tone and painterly details remained.
Watt Restoration March, 12. 2016