Caring for an oil painting...
Remember, unlike some other mediums, oil paintings continue to cure for months and years even after the surface appears to be dry to the touch. As with all art, paintings should be kept away from exposure to direct sunlight. Since oils need to "breathe" and hence are not framed under glass, it is best to hang oils in areas where they will not be exposed to airborne particles of grease or smoke, for exposure to these elements will eventually discolor the surface of the painting.

Never, ever, clean the surface of a painting yourself. That is a job for professionals. If you purchase an old painting or print which needs restoration, take it to a professional framer who can recommend a restoration specialist.

As an artist, I can honestly say that nothing drives me to distraction more than to see beautiful artwork degraded by amateur attempts at framing and preservation. (And believe me, I consider myself an amateur as well in that field.) Treat your work of art like you would a beloved pet — if you can't afford to properly care for one, don't invite it into your home.

— Kate Maynard