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.
Things You'll Need
- Hydrogen peroxide
- Calcium hydroxide
- Distilled water
- Coffee filter
- Glass or other nonmetallic containers
- Cotton swabs
- Safety glasses (optional)
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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.