Any advice about cleaning an oil painting that's covered in dust or yellowed varnish must come with a major disclaimer. More than other kinds of do-it-yourself projects, cleaning oil paintings should really be trusted to expert conservators. Furthermore, altering true antiques almost always decreases their value, whether or not they look better to you. If your painting is not that old, not terribly valuable, or not too important, however, there are a few possible ways to make it look brighter and cleaner yourself.
Before the 1940s, paintings of oil on canvas were frequently covered with a layer of varnish to add sheen and protect the thick layer of paint, called the impasto. Yet varnish reacts differently to the environment than does paint, so these varnish seals end up cracking, yellowing, or gumming up over time. It can make the original hue of the oil paints look dull or discolored.
If it seems that your painting is older, assess whether the paint is in good shape but the varnish has aged. In this case, try applying a mild solvent called a conservation liquid. Art supply stores might sell an "emulsion" designed to clean and remove varnish. There is always a chance that the solvent will also damage or remove the oil paint. If you are willing to risk this possibility, dab the emulsion with a cotton swab very delicately. Try spot-testing one corner before moving on to the entire canvas. Work in an area with adequate ventilation.
For recent paintings, your problem is more likely a build-up of dust, smoke, pet hair, dander, and even bacterial or fungal growth. In this case, make sure none of the paint is ready to come off the canvas or board, meaning that it doesn't exhibit any cracks or flakes. Then you can carefully dust the surface with a very soft, dry bristle brush, such as a baby toothbrush or shaving cream brush.
If the surface is sticky, grimy, or oily, you may want to take the cleaning a step further and actually use a mild detergent solution. Again, generally speaking, oil and water should never mix, as moisture can damage both the canvas and the impasto. Proceeding with caution, use brand new cotton cloths dipped in a mixture of dish soap and warm water. Lightly blot the surface, but don't scrub, wipe, or rub at the painting. At no point should you submerge any part of the painting, nor allow so much moisture that it drips or pools.
For the experimental types, people have come up with some unorthodox methods of getting dirt off an oil painting. White bread seems to work. Ball up soft, sticky, doughy white bread and gently rub it against the canvas. You'll see it blacken like a pencil eraser. Brush off the crumbs. You also might try a low-suction vacuum with a brush nozzle. This should remove pet hair and dust balls in a deeply textured painting.
What Cleans Oil Paint Off Brushes?
Oil paint is created using dry pigments and combining them with refined linseed oil. The oil paints you purchase in stores use nearly the same recipe that has been used for centuries by the old masters who would collect their own pigments. The pigment and oil are mixed together until a smooth and pasty consistency is achieved.
Because the primary ingredient in oil paints is oil, you can't use water to clean your brushes, as the water is simply repelled off the brushes. Artists must instead use solvents to remove oil-based paint from their bristles. Because many solvents such as turpentine and mineral spirits are toxic and can be dangerous when inhaled, any cleaning should take place in a well-ventilated room.
How To Use Oil Paint Brush Cleaner
In addition to traditional solvents, you have the option to purchase a cleaner designed specifically for removing paint from brushes. There are numerous brands on the market, and some claim to be nontoxic and made from natural ingredients. While using solvent as a daily cleanser can provide the best immediate cleaning, cleaners marketed specifically for brushes are also good to use occasionally as conditioners. Follow the instructions on the label for best results.
Solvent Cleaning
Follow these simple steps to use a solvent to clean your brushes:
- Place solvent in a small glass jar or cup.
- Wipe away as much wet paint from your brush as you can with a paper towel or a dry rag.
- Dip the bristles in the solvent.
- Using a clean paper towel or rag, wipe away any color that remains on your bristle.
- You may have to repeat the dipping process one or two more times, depending on how deeply the paint penetrated.
Allow the brushes to air dry naturally and they'll be ready to use the next time you paint.
Safflower Oil Cleaning
Using safflower oil to clean your brushes lengthens the time it takes to clean, but the oil can also work to condition the bristles between uses:
- Pour a small amount of safflower oil into a cup.
- Wipe the wet paint from the bristles of your brush immediately after use. Continue wiping until the color is mostly gone.
- Dip your brush in the safflower oil and massage it so it penetrates all the bristles.
- Place the brush in your brush stand or in a jar with the bristles pointed upward.
- When you're ready to use your brush again, remove the safflower oil and any remaining stain from the bristles with a clean towel.
How Are Oil Paintings Cleaned?
It's important to note that oil paintings are not cleaned with solvent. Using solvent on a finished oil painting could potentially remove pigment and damage the surface of the artwork.
The best way to clean an oil painting is to take it to a conservator. The professional cleaning process is tedious and time-consuming. Generally, the conservator works across the surface of the painting cleaning inch by inch. The instrument used for cleaning is simply a cotton swab or other nonabrasive cloth. The cleaning solution is made up of an olive oil-based soap with water or other archival-safe solution.
Conservators are trained to take as much time as needed to ensure the safety of the painting. They are aware that any water left on the surface of the artwork leaves it vulnerable to decay.
Locating a Conservator
Art conservators can be found in most major cities. For help locating one, visit your local art museum and ask who it uses. Museums generally only hire the best conservators with work renowned in the industry.