If you have ever wondered how to bake polymer clay, what temperature to use or how long polymer clay should stay in the oven, you are not alone. Baking — also called curing — is one of the most important steps in creating a strong, durable polymer clay project.
The good news? Baking polymer clay is easy once you understand a few basic rules.
The most important rule is to always follow the baking temperature and time printed on the package of the specific Sculpey® clay you are using. Different polymer clay formulas can require different baking times and temperatures.
Using an accurate oven thermometer, allowing your oven to preheat fully and giving your project enough time to cure can make a major difference in your finished results.
In this complete polymer clay baking guide, we'll answer some of the most common questions about baking Sculpey® polymer clay and help you troubleshoot common problems such as cracking, brittleness, burning and clay that doesn't seem fully hardened.
How Do You Bake Polymer Clay?
To bake polymer clay successfully:
- Check the package for the recommended baking temperature and time for your specific Sculpey® product.
- Preheat your oven completely.
- Use an oven thermometer to verify the actual oven temperature.
- Place your polymer clay creation on an oven-safe baking surface.
- Protect the project from direct heat when necessary by tenting it.
- Bake according to the package directions and the thickness of your project.
- Carefully remove the project from the oven and allow it to cool completely.
One of the biggest mistakes beginners make is assuming that a hotter oven will cure polymer clay faster. It won't. Excessive heat can discolor, scorch or permanently damage your project.
Correct temperature plus the correct amount of time produces the best results.
What Temperature Do You Bake Polymer Clay?
The correct polymer clay baking temperature depends on the type of Sculpey® clay you are using.
Many popular Sculpey® polymer clays bake at 275°F (130°C), but baking times and even temperatures can vary between products. Always check the package before baking.
For example:
Sculpey Premo™: 275°F (130°C) for 30 minutes per 1/4 inch (6 mm) of thickness.
Sculpey® Soufflé™: 275°F (130°C) for 30 minutes per 1/4 inch (6 mm) of thickness.
Sculpey III®: 275°F (130°C) for 15 minutes per 1/4 inch (6 mm) of thickness.
Super Sculpey®: 275°F (130°C) for 15 minutes per 1/4 inch (6 mm) of thickness.
Other Sculpey products can have different directions, which is why the instructions on the package should always be your first reference.
Can You Bake Polymer Clay at a Lower Temperature?
Baking polymer clay at a lower temperature than recommended does not necessarily make the process safer.
If the clay does not reach the temperature required for proper curing, the finished project may be weak or brittle.
For the strongest results, follow the temperature listed on your clay package.
Can You Bake Polymer Clay Hotter to Make It Bake Faster?
No.
Increasing the oven temperature is not a good way to shorten polymer clay baking time.
Too much heat can cause:
- Darkening or discoloration
- Scorching
- Bubbles
- Cracking
- Burning or smoke
Use the recommended baking temperature and allow the clay the time it needs to cure properly.
Why You Should Use an Oven Thermometer for Polymer Clay
An oven thermometer is one of the most useful tools you can own for baking polymer clay.
The temperature displayed on a household oven isn't always the temperature inside the oven. An oven may run hotter or cooler than its setting, and temperatures can also fluctuate during baking.
That means an oven set to the correct temperature could actually be hotter or cooler than you realize.
Place an oven thermometer where you can easily see it and check the temperature before placing your project inside.
You can also test your oven with a small scrap piece of clay before baking an important project.
This simple step can help prevent many common polymer clay baking problems.
Can You Bake Polymer Clay in a Regular Oven?
Yes. Polymer clay can be baked in a regular household oven when you follow the manufacturer's directions.
Always bake polymer clay in a well-ventilated area, use the recommended temperature and avoid overheating the clay.
You do not need a special professional polymer clay oven to get excellent results.
Can You Bake Polymer Clay in a Toaster Oven?
Yes.
Many polymer clay artists use a dedicated toaster oven for baking polymer clay, especially when they work with clay frequently or want a separate oven in their studio or classroom.
Because smaller ovens can experience temperature fluctuations, an oven thermometer is especially helpful.
Always verify that the oven is maintaining the temperature recommended for your specific clay.
Can You Microwave Polymer Clay?
No. Never microwave polymer clay.
Microwaves heat materials differently from conventional ovens and do not properly cure polymer clay.
Use a conventional household oven or suitable toaster oven and follow the directions printed on the clay package.
Can You Bake Polymer Clay in an Air Fryer?
We do not recommend baking polymer clay in an air fryer.
Many air fryers use powerful circulating heat and may experience temperature fluctuations that can make curing polymer clay inconsistent.
For predictable results, use an oven and monitor the temperature with an oven thermometer.
How Long Do You Bake Polymer Clay?
The correct polymer clay baking time depends on both the clay formula and the thickness of the project.
Always start with the directions printed on your Sculpey® package.
Thickness matters because heat needs time to reach the center of the clay.
A thin pair of polymer clay earrings and a large sculpture should not automatically be treated the same way simply because they are made from polymer clay.
For example, Sculpey Premo™ requires 30 minutes of baking time for every 1/4 inch (6 mm) of thickness, while Super Sculpey® requires 15 minutes per 1/4 inch (6 mm).
Measure the thickest portion of your project and follow the directions for the specific clay you are using.
How Do You Bake Thick Polymer Clay Pieces?
Thick polymer clay creations require special attention because heat needs to reach the center of the project.
Do not increase the baking temperature to compensate for a thicker piece.
Instead, design the project so it can cure properly while following your clay's recommended baking instructions.
For large sculptures, consider creating an interior armature instead of making the entire sculpture from a solid mass of polymer clay.
Aluminum foil is commonly used to create a lightweight core. Clay can then be added over the armature.
Another option for complicated sculptures is working in sections and using multiple baking cycles.
How Do You Bake Large Polymer Clay Sculptures?
Large polymer clay sculptures often benefit from an internal support structure.
A stable armature can:
- Reduce the amount of clay needed.
- Help support larger shapes.
- Provide support for delicate areas.
- Reduce extremely thick areas of solid clay.
Follow the baking instructions for the specific Sculpey® clay covering the armature.
For sculptures with delicate legs or thin supports, some artists also partially bake certain sections first and then attach them to additional raw clay before baking the project again.
What Can You Bake Polymer Clay On?
Polymer clay can be baked on several oven-safe surfaces. Sculpey has a silicone work mat that you can bake on too!
Popular polymer clay baking surfaces include:
Metal Baking Sheets
Metal baking sheets work well for polymer clay.
Many frequent clay artists prefer having baking sheets dedicated specifically to clay projects. If using a surface that is also used for food, follow Sculpey's recommendations regarding an appropriate barrier between the clay and food-use surface.
Aluminum Foil
Aluminum foil has many uses when baking polymer clay.
It can be used as a baking surface, for tenting projects, supporting shapes and creating temporary forms or armatures.
Parchment Paper
Parchment paper creates a smooth surface and can help prevent unwanted shiny areas where the clay touches the baking surface.
Glass
Oven-safe glass can provide a smooth, even baking surface.
Keep in mind that different baking surfaces heat differently, so monitoring the actual oven temperature remains important.
Ceramic Tile
An oven-safe ceramic tile can also make a useful polymer clay baking surface.
Because ceramic tile can take longer to heat, allow the oven and baking surface to preheat properly.
Paper and Index Cards
Regular printer paper, cardstock and index cards are popular surfaces for polymer clay projects.
Index cards can be especially useful in classrooms because each student's name can be written on their card before baking.
For very thin, flat projects, remove the piece from the paper after it comes out of the oven so curling paper does not affect the shape of the clay while everything cools.
Should You Cover Polymer Clay While Baking?
Covering or tenting polymer clay can help protect a project from direct radiant heat.
This can be especially useful in ovens with exposed heating elements or areas that tend to become hotter than others.
Create a loose tent over your project with aluminum foil or another suitable oven-safe covering.
The goal is not to tightly wrap the clay. You simply want to create a shield between the project and direct heat.
How Do You Know When Polymer Clay Is Done Baking?
Polymer clay is different from cookies or cake because it may not visibly change when it is fully cured.
You cannot reliably determine whether polymer clay is finished simply by looking at it.
Instead, rely on three things:
The correct temperature.
The correct baking time for the clay and thickness.
An accurate oven thermometer.
Allow the project to cool completely before evaluating the final result.
What Happens if Polymer Clay Is Underbaked?
Underbaked polymer clay can appear hard after cooling but may be significantly more brittle than properly cured clay.
It may:
- Snap easily
- Chip
- Break at connection points
- Feel weaker than expected
If you believe your project was underbaked, polymer clay can often be baked again following the correct instructions for the product.
Can You Overbake Polymer Clay?
Polymer clay can be damaged during baking, particularly when exposed to excessive heat.
Signs that your oven may be too hot include discoloration, darkening, bubbles, scorching or smoke.
Always follow both the recommended baking temperature and baking time printed on your Sculpey® package.
If a project begins smoking, remove it from the oven, ventilate the area and thoroughly clean the oven.
Why Did My Polymer Clay Burn?
The most common reason polymer clay burns or scorches is excessive temperature.
This is another reason an oven thermometer is so important.
Do not assume the temperature displayed on your oven is perfectly accurate. Verify the actual temperature inside the oven before baking an important project.
Tenting can provide additional protection against direct radiant heat, but it does not replace correct temperature control.
Can You Bake Polymer Clay More Than Once?
Yes. Polymer clay can be rebaked.
Multiple baking cycles are common when creating detailed sculptures and complex polymer clay projects.
Artists may bake one portion of a project, add additional clay and then bake the project again.
Always continue following the appropriate temperature and baking instructions for the clay you are using.
Can You Add Fresh Polymer Clay to Baked Polymer Clay?
Yes.
Fresh polymer clay can be added to previously baked polymer clay, making it possible to create projects in stages.
When attaching fresh clay to baked clay, make sure the pieces are securely connected and carefully smooth the seams before rebaking.
This technique can be especially useful for detailed sculptures and projects with multiple components.
Why Did My Polymer Clay Crack After Baking?
There are several possible reasons polymer clay cracks after baking.
Common causes can include:
- Air trapped inside the clay
- Poorly connected pieces
- Uneven thickness
- Temperature problems
- Stress at weak connection points
Some cracks can be repaired by filling the damaged area with fresh clay, carefully smoothing it into the surrounding area and rebaking according to the appropriate instructions.
Why Did My Polymer Clay Break After Baking?
If a polymer clay project breaks after it has been baked, the clay or the construction of the piece may be the issue.
Possible causes include:
Underbaking: Clay that hasn't cured properly may be brittle.
Very thin sections: Extremely thin areas can be more vulnerable to stress.
Weak connection points: Parts that were not joined securely may separate.
Project construction: Long, thin or unsupported components may require additional reinforcement.
Pay special attention to joins and delicate areas while constructing your project.
Why Is My Polymer Clay Still Flexible After Baking?
Some flexibility in baked polymer clay can be completely normal, particularly with thinner pieces and certain clay formulas.
A polymer clay piece does not necessarily need to become completely rigid to be properly cured.
In fact, a properly cured thin piece may have some flexibility instead of snapping easily.
Allow your project to cool completely before judging its final flexibility.
Why Didn't My Polymer Clay Harden?
If your polymer clay still seems unusually soft after it has completely cooled, several things may have happened.
The clay may have:
- Been underbaked.
- Been baked at too low a temperature.
- Been thicker than expected.
- Been baked in an oven that wasn't actually reaching the temperature shown on the controls.
Check your oven with an oven thermometer and review the directions on your clay package.
Does Polymer Clay Melt in the Oven?
No. Polymer clay does not melt in the oven when it is baked correctly.
Polymer clay cures with heat.
This curing process changes the clay from a workable material into a durable finished creation.
Always use the recommended temperature. Excessive heat can damage polymer clay even though the goal of baking is to cure rather than melt it.
Does Polymer Clay Shrink When Baked?
Sculpey® polymer clay is designed to retain the shape you created as it cures rather than shrinking the way some other types of clay may during drying.
That makes polymer clay especially useful for projects where details and dimensions are important.
How Long Can Polymer Clay Sit Out Before Baking?
Polymer clay does not air dry.
You can leave an unfinished polymer clay project out while you are working on it without worrying about the clay drying simply from exposure to air.
Keep unfinished clay protected from dust, pet hair, lint and other debris until you are ready to continue working or bake the project.
Does Humidity Affect Baked Polymer Clay?
Properly cured polymer clay generally handles normal outdoor humidity well.
That can be particularly useful for artists selling polymer clay earrings, jewelry or other creations at outdoor art fairs and markets.