Grime, dust and dirt can settle on a painting over time and dull the colours and details. With the right cleaning supplies, you can clean an oil painting yourself at home. Emulsion cleaners and varnish removers take off the dirt, while a new layer of varnish will protect the newly cleaned painting for years. Paint neutraliser is a gentle chemical that cleans the painting and controls the chemical reactions between the paint and the emulsion cleaners or varnish remover so they don't damage the painting.
Lay a large sheet of paper on a work surface. Put on a pair of surgical gloves.
Place the painting on the paper, face up. Apply the neutraliser to the cotton swab. Gently wipe the face of the painting with the cotton swab, to remove accumulated dirt or dust.
Apply the emulsion cleaner to a cotton swab. Test the cleaner's effectiveness by wiping a small corner of the painting. Apply varnish remover to a cotton swab and test another corner of the painting. Compare the corners and decide which product to use.
Apply the cleaning product you have selected to a cotton swab. Gently roll the cotton swab back and forth, instead of scrubbing, over the surface of the painting.
Clean the painting 2 square inches at a time. Use a fresh swab on each section; don't dip a soiled one back into the cleaning product. Continue to check the cotton swab for dirt and grime and any hints of paint coming off the painting.
Apply a small amount of neutraliser to a cotton swab. Gently wipe the surface of the newly cleaned painting with the swab, preferably after cleaning each section. Let the painting dry overnight.
Apply a small amount of gloss varnish to the flat-bristle brush. Brush on the varnish with parallel strokes, always in the same direction to avoid obvious brushstrokes.
Allow the first coat to dry. Apply a second coat, brushing in a different direction than the first coat. This will give the varnish an even finish. Allow the second coat to dry completely before rehanging the painting.
Cleaning the painting in sections, such as sky or background, will make it easier to monitor any change in colour.