How Many Times Can You Bake Polymer Clay?

New crafters often wonder how many times you can bake polymer clay because the package instructions only address the baking temperature and time. 

Polymer clay can be put back in the oven as many times as needed for the project to be completed provided that it is not sealed or coated. Although you can burn polymer clay with an oven that gets too hot, you most likely will not overbake it. This flexibility allows for a lot of design revisions and the ability to build upon designs as you work. 

Can you over bake polymer clay?

Like anything else you put in your oven, polymer clay can be burnt due to overbaking.  This can happen either because you have set it to cure at a too high temperature or because it is left in for too long.  The first case is way more likely.

Overbaked clay can release fumes that can potentially contaminate your oven, which is why polymer clay should always be baked in a dedicated clay oven.

Most of the cooking ovens are not exact when it comes to the temperature you have set them on. So make sure to test them properly before curing your clay piece. 

There is an easy way you can do that. All you need to do is take a small piece of clay, roll it out into a thin, even sheet (but not so thin that it breaks apart when you try to hold it), and put in in your pre-heated oven. A good thickness to aim for is ¼-inch. 

Cure it according to the package instructions. If the colors are visibly darkened in some areas that means the temperature is too high. If it is still soft, then your oven is not hot enough. 

Redo the test as many times as needed until you achieve the proper setting. This will vary across each polymer clay brand, so it’s a good idea to take notes while you’re running your tests.  

Change your temperature to plus (if the oven was not hot enough) or minus (if it was too hot) 10 degrees Fahrenheit every time you try it. Lower than that will not make much of a difference and higher will result in a huge one. 

The pieces you are testing should have an even thickness. Compare them to check how the clay behaves under different settings and choose the one that produces the best results. 

Consider buying an oven thermometer – the digital ones are easier to use and have some useful features. Having one will make your testing process much easier. 

What happens if you bake polymer clay too long?

Longer bake times usually result in a stronger clay project. If you’re running into issues with your clay, check the temperature before suspecting the bake time. That being said, it is possible to bake clay for too short of a time. 

Keep in mind that some light-colored clays or liquid clays can become darker if baked for long periods of time.

How long does it take to bake polymer clay?

Each polymer clay brand is slightly different.  In general, it takes approximately 30 minutes for every quarter inch of thickness. The thicker and larger your piece is, the more time it will need to cure fully. 

What does polymer clay feel like after baking?

When you take out your piece from the oven, it will still be soft and flexible at first. Do not worry, this is completely normal. You have to wait for it to properly cool down from the heat to reach its final form. 

A common misconception is that polymer clay turns rock solid after curing. This is most likely not the case. Thin pieces will be noticeably flexible after cooling, whereas thicker pieces may not physically flex but they will be able to be damaged if you scrape them forcibly. 

Baked polymer clay will not feel hard like glass or metal. 

How do you know when polymer clay is done baking?

After you are done with your oven tests and you are sure that your piece will be cured at the proper temperature, simply adding 20-25 minutes to the time stated on the package instructions will ensure that your clay will be baked well.  

The instructions usually give out average values. The instructions try to balance the inaccuracy of ovens and the proper amount of baking, which can sometimes result in a recommended number that misses the mark.

If that is not enough for you, there is a classic and seemingly unconventional test that you can do to check if your piece is done baking. It is almost impossible to tell if polymer clay is baked or not solely by looking at it. You have to attempt to break it. 

Wait for it to cool down completely so it has reached its highest hardness level and curve it with your fingers. If the clay is properly baked, it should be very bendy. 

Really soft polymer clay brands like Sculpey Original and Sculpey III are an exception – they are both extremely brittle and easy to break even when ready. So do not try this on them.

But if you are using a stronger brand, you can be sure this will not happen. Improperly cured clay will crumble or break in your hand easily. If you think it is not ready yet, bake it again.  Rebaking will not cause any damage. 

A general rule of thumb is the following – if in doubt, bake longer. Longer baking at the proper temperature will not cause damage to your piece, especially if it is covered. 

Will polymer clay harden without baking?

Although often confused with air-dry clay, polymer clay always needs to be heat cured in an oven to harden. If it is not, the clay will not become hard and durable.

What surfaces do you use for baking polymer clay?

There are a handful of possible surfaces you can use to bake your polymer clay projects on. The most important characteristic a baking surface should provide is even heating.

Many crafters use various types of tiles, aluminum foil-lined baking sheets, or aluminum baking pans. Make sure you are not putting plastic in the oven. Although plastic sheets can make a good work surface for polymer clay, they are not suitable for the curing process.