how to soften polymer clay

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You gather your clay tools and excitedly pull out your favorite colors of polymer clay to start a new craft when you notice the clay begins to crumble in your hand. While you're used to clay feeling a little stiff before conditioning from previous projects, this clay feels harder than it should be, and you wonder if it's still OK to use.

Clayers and crafters often ask about what to do with polymer clay that's become too hard. Can clay become too firm to the point where it's unusable? The answer is yes and no. The good news is that you can bring that clay back to life, making it good as new in most cases! Learn how to revive dry, extra-firm and crumbly clays with these super helpful polymer clay softening tips.

how to soften polymer clay

Issues of Working With Hard Polymer Clay

Sometimes, you can store polymer clay for years and it'll still be supple when you pull it out. If stored properly, polymer clay will last a reasonably long time. If you find your clay is too hard or brittle, it's essential to return it to a soft polymer modeling clay consistency before use. Here's why:

  • Hand fatigue: Stiff clay affects your clay-shaping experience. Hard clay causes hand fatigue, requiring more force to condition, smooth and work it properly.
  • Blending difficulty: Crumbling clay won't blend seamlessly, even if you use the best tools for the job. Dry clay makes it difficult to remove visible seams from clay pieces.
  • Poor project quality: Baking too-hard clay can lead to cracks and weaknesses in its final form. Even if the baked piece looks OK, the clay is more susceptible to breaking and chips long term.

Because of the nuanced nature of clay and the various factors that can cause it to stiffen, we've put together some tips and tricks on how to soften modeling clay.

Why Is My Polymer Clay Hard?

Maybe you've opened a box of old polymer clay and found that it's stiff as a rock. Or, perhaps your clay is just slightly hard and crumbly. Can you soften hard polymer clay? The answer is yes — as long as the hardness is not due to the clay being cured. 

Because oven-bake polymer clay cures at low temperatures, it's possible for clay to "bake" partially if it's left in a hot place for too long. It's a rare occurrence, but if clay reaches 100 degrees Fahrenheit or hotter for an extended period, it can accidentally "cook" beyond the point of saving. If you leave clay in a hot car during a summer heatwave or in a sunny attic for weeks on end, the resulting hardness may become permanent.

Test the Clay Stiffness

Before adding any materials to the clay, first test its hardness by giving it a hard squeeze, or a "squish test." With workable clay, even if it's a bit cold, you should at least be able to round off the corners and edges with minimal effort. If you cannot round off the corners, or the block of clay isn't squeezable in the slightest, then it's too hard and needs to be softened.

Fortunately, the most common reasons for clay hardness are a lack of conditioning or the loss of plasticizers, both of which are easily fixed! Learn how to make polymer clay soft again using the following strategies.

Five Ways to Soften Hard Polymer Clay 

five ways to soften polymer clay

Polymer clay that is too old can adopt a rock-like consistency that makes it impossible to shape — at first. With a little work, your clay can bounce back! 

Here's how to soften hard polymer clay in five different ways:

1. Smash and Soften

This technique is best to soften older polymer clay that is just a bit firm and simply needs to be conditioned well before use. Place the clay inside a plastic bag and pound it with a mallet or rolling pin to "smash" it until it starts to move. Once the clay is warm and broken up, condition it further by hand or with a conditioning machine.

2. Use a Conditioning Machine

Sometimes all clay needs is a good conditioning session to make it workable, especially if it has been sitting on the shelf a long time. With some elbow grease, you could try to knead the clay by hand and use a clay roller like our Sculpey ToolsTM Acrylic Clay Roller to soften it. 

We recommend passing extra firm polymer clay through a pasta machine or clay conditioning machine several times. Our Sculpey ToolsTM Clay Conditioning Machine does the bulk of the conditioning work for you, quickly pressing hard clay and removing trapped air to create a flexible sheet of clay. 

3. Mix It With a Clay Softener

Conditioning clay alone may not be enough to soften it, in which case, it's time to add a plasticizer. Also known as clay softeners or conditioners, these plasticizers and oils can reconstitute your clay:

  • Liquid clay softener: Add 2-4 drops of our clear Sculpey® Liquid Clay Thinner & Softener per 2 oz. of clay to soften it without affecting the color quality. Slowly add one drop at a time, mixing and kneading after every drop until the desired clay flexibility is achieved.
  • Solid clay softener: Pinch off a small piece of our solid-form Sculpey® Oven-Bake Clay Softener and mix it into your dry clay, slowly adding small amounts until reaching the appropriate level of softness.
  • Compatible oils: If you only need to increase the softness a tiny amount, you can add 1-2 drops of pure mineral or baby oil. If the clay requires more liquid to bounce back, use Sculpey® clay softeners to ensure the final clay formula isn't diluted.

If you add too much softener and find you now have mushy clay, there's an easy solution! Some of the conditioner can be leached out by using a heavy book to press the clay between several sheets of ink-free white paper for a few hours. Protect your work surface and the book from conditioner transfer with a wax paper or aluminum foil barrier.

soften polymer clay with clay softener.

4. Combine With Softer Clay

Another option to revive stiff clay is to combine it with fresh, soft polymer clay. While adding new clay makes the old clay pliable, it can also affect the color. If you don't have the same color on hand, mixing the old clay with a similar hue will subtly lighten or darken your clay.Translucent clays are usually softer than opaque ones, making them a great alternative to mix into your old polymer clay. Keep in mind this will increase your clay's translucence.

5. Use a Food Processor

If your polymer clay is extra dry, brittle or hard as a brick, try crumbling it into a crafts-designated food processor and gently pulse the machine to create evenly sized clay pieces. Add your plasticizer of choice little by little, pulsing the processor to blend it with the crumbles.

Remove the plasticized clay and seal it in a plastic bag. Let the clay sit for several hours or a few days, depending on the severity of the dryness. Then squish and knead the clay to determine if it's soft enough. Add more softener as needed and condition the clay thoroughly before use.

Shop Sculpey® Polymer Clay Softeners and Conditioning Tools

We are proud to offer crafters the highest quality polymer clay, tools and clay conditioners on the market. Shop our innovative clay softeners and conditioning tools online to keep your collection of long-lasting Sculpey® clays soft, pliable and ready to use for your next creative project!

shop sculpey clay softener and conditioning tools