Polymer clay doesn't go bad the way people think. What goes is the plasticizer - the oil mixed into the clay that keeps it soft and pliable. After a couple of years on the shelf, blocks of Premo, Fimo, or Sculpey can crumble in your hands and pasta-machine into shards. Most people assume the block is dead and throw it in the bin.
It isn't. A drop or two of oil - mineral oil, baby oil, or Sculpey Clay Softener - mixed into the broken-up clay puts the plasticizer back. Cindy Lietz from PolymerClayTutor walks through the method on a block of old Fimo that had gone almost to powder. Five minutes later it's a smooth, pliable lump you can sculpt with.
This guide covers the oil method in detail and finishes with quick notes on the two other ways crafters condition hard clay (hand-warming plus pasta machine). The oil method is the rescue technique. The other two are for clay that's only stiff, not dust-dry.
Why polymer clay gets hard
Three things cause it, and only two can be fixed.
- Plasticizer loss. Old clay, or clay left unwrapped on paper, which wicks the oil out. Fixable with oil.
- Cold. Clay stored in a cold garage is stiff but fine. Warm it in your hands.
- Partial curing. Clay stored near a sunny window, a radiator or in a hot car can start to cure. That cannot be undone.
Old clay or partly baked clay?
Old clay crumbles into dry, chalky bits, and once oil goes in, it comes back together. Partly cured clay feels rubbery. It tears instead of crumbling, stays in tough lumps however long you knead, and leaves hard specks in a rolled sheet. If a block still has rubbery bits after oil and ten minutes of work, retire it. Those specks will show in the finished piece.
Which softener to use
| Softener | Best for | Notes |
|---|
| Mineral or baby oil | Dry, crumbly clay | Cheapest. Unscented only. |
| Sculpey Clay Softener | Any brand | Made for the job. Same idea as oil. |
| Liquid clay | Stiff but not crumbly clay | Softens and still bakes solid. |
How much to add
Start with one drop for a 2 oz block and knead it all the way in before adding another. Most rescues take two to four drops. Too much oil makes clay sticky, mushy and prone to fingerprints. If you overshoot, press the clay between two sheets of plain printer paper for an hour and the paper pulls the extra out.
Conditioning with a pasta machine
Once the clay holds together, roll it through a pasta machine on the thickest setting, fold the sheet in half with the fold going in first, and roll again. Twenty passes or so and it turns smooth and even. Go a notch thinner only once it stops cracking at the edges. For a crack-free surface before baking, see how to smooth polymer clay.
Storing clay so it stays soft
- Wrap opened blocks in plastic wrap or wax paper, never plain paper.
- Keep them in a lidded container somewhere cool and out of the sun.
- Some plastics react with raw clay. Polypropylene (recycling number 5) is safe.
Common mistakes
- Dumping in oil. One drop at a time, every time.
- Baking too soon. Freshly oiled clay can be soft. Rest it an hour before you sculpt fine detail.
- Skipping a test piece. Bake a small scrap first to check it cures hard.
With the clay workable again, it is ready for a project like polymer clay earrings. Then follow how to bake polymer clay to cure it without scorching.
