Whether you found a fabulous but dirty oil painting at a thrift store or you have a family classic hanging on a wall, oil paintings sometimes need cleaning. This is largely due to dirt and pollution accumulating on the painting's varnish.
Only attempt home cleaning methods on paintings which have little value; never attempt to clean a valuable painting yourself. Ask an art conservator, found through your nearest local art museum, for help with valuable art.
Remove the Painting from Its Frame
If there is a frame, remove the painting from it and lay it on a flat surface before you begin. Check the sides of the canvas to see if there is any paint there; this hidden area is a great place to test any of these methods.
Use caution if the painting appears cracked or flaky. These home methods will likely make the condition worse.
Take a "before" photo of the painting, so you can have a record of what it looked like before you began. Take another photo afterward and compare the two.
To clean the painting properly, first try to get as much dust off of it as possible. Use a soft brush, such as a baby toothbrush or a sponge. Be wary of using a sponge if the paint is flaking off, because it will cause more paint to come off.
Another method you can try is to simply take a piece of white bread and blot the painting with it. The bread absorbs grease and dirt.
Homemade Cleaning Solutions
Briana Cecil-Satchwell of Overstockart.com recommends using a few drops of a mild dishwashing detergent on a damp, clean cloth. Test an inconspicuous area of the painting, such as the part hidden under the frame, by rubbing the solution gently over the dirty paint. Stop if any paint comes off.
If the dishwashing detergent doesn't do the job, she suggests using a small amount of rubbing alcohol on a cotton ball to clean the painting
Another home remedy for cleaning oil paintings is to cut a big white potato in half, then rub the white moist part over the painting. Do this gently; do not use brute force to try to get the dirt off. The dirt will stick to the potato. Then blot the painting with lukewarm water and a soft cloth to clean off the potato residue.
Cleaning with Art Restoration Products
Should the home methods not appeal, try art restoration products like Gainsborough Emulsion Cleaner (see Resources below). These are chemicals that are made specifically for restoring oil paintings. Wear rubber gloves, follow their directions, and have adequate ventilation.