I listened recently to a fascinating talk on ABC radio by a woman called Katya, who is an expert on the restoration and conservation of paintings. People rang in to ask her advice on this and that, and she gave interesting and informative answers. Then Betty from Ballarat asked how to clean an oil painting.
"You will need a litre of female human urine", said Katya confidently. "Put it in a plastic ice cream tub and leave it in a sunny place in the garden for a week. Evaporation will reduce it by half and you will find that it has quite a clean, ammonia-like smell. Add two tablespoons of finely grated potato and a tablespoon of salt, stir well and leave for half an hour. Dip a clean cloth into the liquid, wring out well so that the cloth is just slightly damp, and wipe your painting gently."
I checked my calendar. No, it is not April 1st. So I fired up my computer and asked Google for a second opinion on the matter.
There are oodles of websites about the care and cleaning of oil paintings. None of them mention bodily fluids of any kind. The consensus seems to be that the best way to clean an oil painting is to take it to an expert conservator. (Before handing my painting over, I would take the precaution of asking where they stand in the matter of female human urine.)
If you are determined to go DIY, then the white bread method seems to be the way to go. 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.
Some hints for the basic care of oil paintings are:
1. Do not hang them where there is excessive exposure to light, high and/or fluctuating temperature and humidity levels, dirt or insects.
2. It is a good idea to hang them at a 10 deg forward tilt, so that dust can't settle.
3. A soft brush should be used regularly to remove surface dust and dirt from paintings and frames. Dirt serves as a host for mold growth and the absorption of pollutants and moisture onto the surface of a painting.
4. If there is flaking paint no attempt at cleaning should be made.
5. Paintings should not be displayed in smoking areas or in close proximity to candles or fireplaces which can deposit nicotine and soot onto the surface of the painting.
6. Do not attach holiday decorations to paintings. Paper streamers, live greens and berries can stain and damage frames and paintings. They also introduce pests into the environment.
7. Carpet beetles and powder post beetles, to name but two, subsist on sizing materials and wood. They can do substantial damage before they are noticed, so paintings should routinely be taken down and examined for pests.
8. The greatest amount of damage is caused by careless handling. Prior to moving a painting, be sure to remove all jewellery, belt buckles, etc. so that the painting is not accidentally torn or scratched while being moved. Always hold the painting from both vertical sides, not at the top of the frame or by its hanging wire. It is important to avoid bumping canvas paintings as even the slightest bump can cause future cracking of the paint surface.