This article has been taken from “Formulas for Painters” by “Robert Massey”. Paint cleaners , is a chemical product designed to remove paint, finishes, and coatings while also cleaning the underlying surface. This process is well described at “Painters in Rockville MD“.
Tempera or Gouache:
To clean egg tempera or gouache paintings, rub the surface with bread crumbs or with a kneaded eraser. Do not use cleaning solutions.
For a light cleaning of varnished surfaces, wipe with a rag dampened in turpentine or alcohol. A combination of turpentine and Copaiba balsam (five parts turpentine, one part balsam) reduces the cutting action of the solvent, making it safer to use-less likely to damage the surface of the painting.
Fresco requires gentle treatment even when the lime skin is still strong and intact. Try distilled water alone, or non-greasy bread crumbs of heavy bread. Remove stubborn dirt with equal parts of Castile soap solution, distilled water, and ethyl acetate. This solution must be kept agitated in order to combine the solvent with the soap.
Ammonia water can be used directly-but sparingly-on stubborn areas of dirt or it can be added to turpentine or alcohol to make them more effective. Household ammonia can be rubbed on gently to remove grease from paper.
For cleaning or restoring faded or yellowed water colours, fill a basin larger than the picture with water and borax (60 parts water, 1 part borax). Soak the picture in this solution for half a minute, then remove and lay the paper on a sheet of clean glass. Dry it away from direct heat. This treatment should restore some of the brightness of the colors. Where a print or a water colour has yellowed outside the printed or painted area, blot the yellowed area with a blotter soaked in peroxide for a few seconds at a time. If, after drying, the spot persists, repeat the treatment.
Patches and tears in paper
To repair tiny holes in paper or to cement torn fibers, take a piece of (or scrapings from) the same paper; soak it and combine the resulting paste with a little starch paste. Lay the paper flat and dampen the edges of the hole or tear sufficiently to accept the paste and fiber. Apply it carefully and lit it dry.
To remove creases, dampen the paper thoroughly between wet blotters and leave it to dry flat on a wet plate of glass.
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