The first step in cleaning an oil painting is to remove the painting from its frame. Make sure the frame is on a soft surface to prevent damage. Once the frame is off, use a vacuum to clean any cracks where the paint meets the wood frame. Be careful not to chip the paint.
The next step is to remove the mold. Using a cotton ball and sodium hydrochloride cleaner, gently rub the affected spot on the paint. Before you continue, check the cotton ball to make sure the paint doesn’t come off. Once the area is clean, immediately wipe the clean area with a damp sponge. Be sure to remove all of the cleaning agent.
To clean a small amount of dirt and grime, use an onion cut in half. Potency can be increased by adding lemon drops. Do not allow the onion and lemon mixture to dry on the paint. Clean with a damp sponge. If the dirt still persists, go on to clean with a lemon detergent. A soft sponge with warm water should be used. Use as little water as possible. After cleaning, wipe off all the detergent.
For a higher level of dirt and grime, use soda ash. The concentration should be determined before using the solution on the entire canvas. The way to do this is by dissolving a small amount of soda ash in warm water, then test the mixture on a corner of the pain with a cotton ball. Continue this process until the mixture removes the grime without stripping the paint. After cleaning, rinse the soda ash with fresh water, or it will leave white streaks.
If the paint is so dirty that the above methods don’t work, the next step is to remove the varnish. What is needed to remove the varnish is methylated spirits, turpentine diluted with linseed oil, and several cotton balls. Use the cotton ball covered with methylated spirits to remove the varnish. It is important not to go deep, remove only the varnish, and not the paint from under it. The method used to protect the paint underneath is after removing the varnish, use a new cotton ball coated with the linseed oil and turpentine mixture to stop methylated spirits. Continually check the cotton ball to make sure the paint isn’t coming off. If the paint starts to peel off, use the linseed oil and turpentine mixture to stop it.
After cleaning the paint it is necessary to re-varnish the paint. The varnish can be gloss or matte and should be applied in a criss-cross pattern with a varnish brush. Let dry.