Things You'll Need
Glass or other nonmetallic containers
Safety glasses (optional)
Paper can degrade over time for a number of reasons, which include light, moisture and oxidation problems. Foxing, a term referring to the brown blotches appearing on a print, results from airborne microorganisms, humidity and the presence of metals and fungi. To restore a lithograph print, use caution and a delicate touch using this traditional bleaching method to spot-restore your prints. As always, use discretion when altering or performing other procedures on a piece of art---consult an expert if you are not sure how a procedure will affect the particular pigments and paper used.
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Before mixing anything, check the condition of your paper. If it is thin or brittle, do not attempt anything without expert advice. Paper should be pliable and resilient. Pencil, ink and dirt will not be lifted by the bleaching process.
Wear gloves while preparing the bleaching solution and throughout the remainder of the process. Dilute the distilled water and hydrogen peroxide (3 percent solution) in a 1:1 solution.
Prepare the neutralization solution in a separate container. Pour 1 tsp. of calcium hydroxide into one liter of water. Mix well, then filter the water through a coffee filter placed in a stable container that supports the sides of the filter and allows the water to drain freely through and out the bottom. According to Dr. Andreas Grund, the process removes instances of acidic substances; what remains is a crystalline substance. Mix this into 1 liter of distilled water.
Measure a few teaspoons of the hydrogen peroxide solution into a small glass container. Dr. Grund warns against double dipping a cotton swab that has touched the paper back into the working container, as the presence of pigments and impurities can degrade the solution.
Place the lithograph print on the towel (using paper beneath the print can upset the process by causing bleeding of the chemical solution). Wet the area gently around the stain with water to control the peroxide solution when it reaches the paper.
Apply the bleach with a cotton swab over the affected area every 30 minutes over a period of one to four hours. When the process is done, rinse the area where the solution was applied by rubbing a cotton swab, moistened with distilled water, lightly over the surface three to five times, using a clean swab with each pass.
Apply the calcium hydroxide solution with a cotton swab; this solution does not need to be rinsed off. Allow the paper to dry.
Avoid using too much solution at one time, as this can cause the paper to become oversaturated. The bleaching process is slow and requires patience, as results are not immediately apparent. If foxing is consistent throughout the surface of the print, consult the resource on cleaning Shin Hanga prints (listed at the end of this article) for a print wash or complete bleaching (recommended using 1:2 peroxide to distilled water ratio). While the method is applied to a different type of print, the same procedure applies.
Rubbing the print while it is wet can cause the oils from your skin to contact the paper and can smudge pigments. If you are working with a rare or valuable print, consult an expert for advice before attempting any procedures. Professional art restorers have specialized knowledge concerning the type of paper and ink used, and how different processes can affect it. Several other methods are commonly used for bleaching prints, such as ultraviolet (UV) light treatment, oxidation and other bleach processes. Be very careful when attempting these procedures, as they are risky and may yield unpredictable results.