You just inherited a box of oil paints from your recently-deceased grandmother. They're so old the addresses on the tubes don't even use zip codes. So, are the paints still good?
If the tubes haven't been punctured and the caps are on securely, yes. So long as oil paint hasn't been exposed to air, it should still be fine. Oxygen is what causes oil paint to dry. (It actually doesn't dry but polymerizes.) You may have to wrench the cap off with a pair of pliers, but if the paint is still fluid enough to squeeze out, it's usable.
Sometimes, though, the oil and the solids in the paint will separate. If this happens, you can squeeze the separated oil out on a newspaper to get rid of it; if there's a lot of it, though, the paint may no longer have sufficient oil for the paint to be fluid. If the paint is unworkable, toss it.
Of course, none of this is a problem with pastels! Pastels stay good for decades, maybe even centuries. I pulled out a couple of old boxes of Grumbacher pastels for you to see. Grumbacher hasn't made square pastels for years, and these are square. One of the boxes doesn't have a zip code, which dates it back to at least 1963.
I thought I'd also include a recent pastel (made with fairly new pastels) for your enjoyment. If you'd like to purchase it, you can do so in the studio store.
|Oak Creek Ripples, 12x9, pastel|