I have adapted this Masterson Sta-Wet palette for cold wax/oil as follows: I put leftover paint on a sheet of freezer paper that fits in the bottom half, I put a few drops of gamsol on the top of each pile of paint, then cover with saran wrap, then put the lid on top. If you have the sponge, you can dribble some gamsol on that as well and place over the saran wrap. Then, put on the lid and the paint should stay fresh for several days!