Like most polymer clay artists, I always make way too much of custom colors when I'm making one of my pieces. I'm always afraid I'm going to run out before I'm finished. Consequently, I usually find that I have lots left over. I'll wrap the left overs in plastic wrap, put them in my stash, which is a large plastic tote bag and forget about them.
Then, sometimes months later, I'll find them again and get an inspiration for a new piece. Unfortunately, the balls of polymer clay have dried out and are hard and crumbly and basically unusable. I'm always bummed out when this happens and I'm way too unorganized to have written down the recipe of how I made this particular color.
I've picked up a few tips on how to rejuvenate these sad lumps of clay:
Tip 1: Sit on it! I've found that if I put the hard clay on my chair and sit on it for a while, the warmth of my body will help soften it enough so that it eventually becomes pliable enough to knead with my hands.
This is usually a long and tedious process but it does work, sometimes. Just be sure you wrap the clay in plastic wrap before planting your butt on it, otherwise you might end up with polymer clay smears all over your favorite pair of jeans and/or your chair!
Tip 2: If your not planning to sit for any length of time, wrap the polymer clay in plastic wrap and put it in your pocket. Same theory as the method above, but you'll be mobile and won't have to sit in your chair.
Tip 3: Add some liquid polymer clay to the mix. I use Sculpey Translucent Liquid Polymer Clay because I bought several bottles of it years ago and haven't used it up yet. It's still good and I'm too cheap to go out and buy some more.
This method can get messy, though. I use it when the clay is a bit pliable but cracks when it's run through my clay pasta machine. You can roll out a sheet of the semi-workable clay, spread some liquid polymer clay on it, then fold it, trying to seal the edges and run it through the pasta machine. The liquid clay usually squirts out the sides and gets all over everything, but it does work. Another method is to knead the clay with some liquid clay mixed in with your hands until it's pliable enough to work with. Either method is quite messy, so be prepared to have liquid clay all over your hands and quite possibly your entire work space!
Tip 5: This one's not for rejuvenating the clay but is an alternative on how to use that dried up ball of clay. Grate it! Use an old cheese grater (one that you don't mind delegating to the exclusive use with polymer clay) and grate up the mummified clay. The subsequent shavings can be used as an inclusion in fresher clay. This method can be used to make simulated turquoise or any other type of stone or material that has inclusions in it.
Well, that's it for today. I've been sitting on a hard lump of polymer clay (wrapped in plastic, of course) and now it's time to see if I can work with it. Hope these tips help you out in your polymer clay journey!