Clove Oil
For the alla prima wet-into-wet oil painter – I recommend putting a few drops of Clove Oil around the edges of your sealed palette container (not directly in the paint) when you’re working on a longer studio painting. This will slow down the dry time of the oil paint. You can return to the painting a week later and it will be as wet as if you didn’t leave at all. 2 weeks isn’t uncommon either. It also keeps the paint on my palette wet forever. Clove oil along with an air tight seal (more on my masterson pallete) is the perfect combination to keep your paints fresh. I have a glob of white on my palette that has been wet for over 3 months… Amazing.
Be careful though, if you want certain areas on your painting to dry for layering techniques, you might be waiting for a while. And if you know the painting will be getting shipped somewhere soon, I wouldn’t recommend it either. To be safe, plan on 4 weeks for it to be dry to the touch. Otherwise, I love this stuff. It does exactly what it’s supposed to.
The only source I know of to get pure clove oil is LorannOils.com, recommended by Jeff Watts. Watch out, the stuff you get from Trader Joe’s isn’t pure and I haven’t tried it. So, I can’t vouch for it. If you find another source, please share in the comments. Also, get an eyedropper since it comes in a bottle. Please don’t pour it on your paints!