Polymer Clay

How to Avoid Cracking in Polymer Clay: The Ultimate Guide

Cracking in polymer clay is often caused by changes in temperature and humidity. Clay that has been exposed to extreme temperatures or too much moisture can become brittle and crack. If the clay has cracked, it is important to identify the cause of the cracking before attempting any repair. It may be possible to reverse the damage if caught early enough.

When polymer clay cracks due to temperature changes, it is typically because of the contraction and expansion of molecules within the material as it heats up or cools down. This can happen quickly when clay is not protected from sudden temperature shifts, such as leaving it out on a hot summer day or putting it near an air conditioner vent on a cold winter night. To prevent this type of cracking, store your clay in a cool, dry environment and keep it away from direct sources of heat or cold.Polymer Clay

Humidity can also cause polymer clay to crack. Clay that has been exposed to too much moisture can become soft and brittle. It is important to make sure the working area is well ventilated before using the clay and always store it in an airtight container after you have finished with it. Additionally, if you are using water-based mediums such as glazes or paints with your clay, it is best to seal the finished piece with a waterproof varnish or finish so that any excess moisture does not penetrate into the material and cause cracking.

If your polymer clay project has already cracked due to extreme temperatures or humidity, it may still be possible to repair it. If the crack is minor and shallow, you can often restore the clay back to its original shape with gentle heat from a hairdryer or an oven set on low temperature for just a few minutes until it softens. For deeper cracks, you may need to fill in any gaps with additional polymer clay and re-bake the piece as instructed by the manufacturer’s instructions.

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No matter what caused your polymer clay to crack, it is important to identify the root cause of the problem so that it does not happen again. With proper care and storage precautions, you can prevent future cracking in your projects and ensure they last longer.

The effect of temperature on Polymer Clay

Polymer clay can be affected by temperature changes. Changes in the temperature of the environment, as well as the heat generated from your hands when you are working with the clay, can cause it to crack. When polymer clay is exposed to very cold temperatures or hot temperatures for a prolonged period of time, it will become brittle and may crack. In addition, if the polymer clay is heated too quickly, such as when using a heat gun or oven, then this rapid heating can also cause the clay to crack.

To prevent cracking in your polymer clay projects, be sure to work in an environment that has consistent moderate temperatures. If necessary cool down any tools before utilizing them so that they will not overly heat up the clay while you work. When baking, use the recommended oven temperatures and avoid rapid changes in temperature. Finally, be sure to look for any signs of cracking or brittleness as you work with your clay so that you can take steps to prevent further issues. With careful attention to temperature and proper handling techniques, you should be able to successfully create beautiful polymer clay creations.

Overworking the Clay

One of the most common reasons for cracking in polymer clay is overworking it. This means that too much pressure or heat has been applied to the clay during its creation. Kneading, rolling, flattening and shaping the clay can cause stress points which may lead to cracks when the clay is heated during baking. To prevent this from happening, it’s important to work with light hands and not press down too hard on your clay while shaping it. It’s also beneficial to have a slow and steady heating process when baking your creations to allow them time to adjust more gradually to temperature changes. Following these steps should help you avoid cracked results in your finished pieces.

Another way to prevent cracking is by layering your clay. If you have a design that requires more than one layer of clay, make sure there is some give between the layers. This will help cushion any stress caused when the pieces are being put together and baked, which should result in fewer cracks or other noticeable imperfections.

Finally, it’s also important to use an appropriate baking time for your project. Overbaking or underbaking can both cause cracking or other deformities in finished pieces. Check with your polymer clay manufacturer regarding their recommended baking times, as each type of clay may require different temperatures and times when baking. Following these guidelines should help you achieve successful results with minimal cracking!

Poor quality or old Clay

One of the main reasons for polymer clay cracking is poor quality or old clay. Poor-quality clays are often brittle, so when they dry out after being exposed to air and temperature changes, they become more prone to cracking and breaking. Additionally, older clays tend to lose elasticity over time, making them less likely to bend and stretch without cracking. For this reason, it’s important to always use fresh clay whenever possible.

Overworking the Clay

Another common cause of polymer clay cracking is overworking the clay. As you roll out or sculpt with your polymer clay, you can create tiny cracks on its surface. These cracks may be too small for you to see at first but can grow larger as the clay ages and dries. Additionally, if you press too hard when sculpting the clay, it can cause it to crack or break apart entirely. To avoid this issue, make sure to use a light touch when working with polymer clay.

Temperature Changes

Finally, sudden temperature changes can also cause polymer clay cracking. When exposed to extreme temperatures or heat sources like direct sunlight, microwaves, and ovens without taking proper precautions (such as pre-conditioning the clay), polymer clays may become brittle and prone to cracking due to thermal shock. To protect your clay from thermal shock, make sure to condition it before baking in an oven and take appropriate steps when using any other heat source on your project.Polymer Clay

By understanding the reasons why polymer clay cracking occurs, you can take the necessary steps to protect your projects from it. Taking proper precautions such as using fresh clay and pre-conditioning before baking will help ensure that your creations stay strong and durable for years to come.

Storing Polymer Clay improperly

Proper storage of polymer clay is important, as it can be affected by extreme temperature changes. Polymer clay should never be stored in temperatures below 32°F (0°C) or above 120°F (49°C). Additionally, the level of humidity in the air will also affect the polymer clay and could cause it to crack. To prevent this from happening, store your polymer clay in an air-tight container with desiccant packets to keep the moisture level low. Finally, make sure that you store your polymer clay away from any direct sunlight or heat sources. By following these steps, you should be able to keep your polymer clay from cracking due to improper storage conditions.

The impact of humidity on Polymer Clay

Excessive moisture in the air can cause polymer clay to crack. This is because the clay absorbs the excess humidity, causing it to expand and resulting in cracks on its surface when it dries. As such, storing polymer clay in dry environments and avoiding exposing it to high levels of humidity is essential to preventing cracking. Additionally, adding a sealant layer over your finished projects can help protect them from absorbing too much moisture from their environment. Taking these steps will ensure that your polymer clay items remain looking their best for as long as possible!

Fixing Cracks in Your Polymer Clay Creations

Also, make sure you keep any sculpted pieces or other objects made out of clay away from heat sources like radiators or windowsills since too much heat can also cause the clay to crack due to the temperature expansion. Working in a cool, dry environment will help to reduce any cracking issues you might experience.

Finally, if your polymer clay does end up cracking after it has already been fired and cooled off, you can use sandpaper or an X-Acto knife to gently remove any sharp edges and fill in any gaps with more clay before baking again. This should help to restore your project back to its original state!

Baking Polymer Clay at an incorrect temperature

One of the most common reasons for cracking polymer clay is baking it at an incorrect temperature. Polymer clays have different baking temperatures, depending on the brand and type of clay. Be sure to check your manufacturer’s instructions before baking the clay piece you are working with. Over-baking or under-baking can cause the clay to crack, as well as shrink or expand too rapidly and unevenly.

Improper conditioning

If your clay was not properly conditioned before use, it may be more prone to cracking during baking. Clay needs to be kneaded and mixed regularly in order to keep its malleable texture and prevent cracking when baked. This will also help avoid air bubbles in your finished piece.

Too much moisture

If your polymer clay has been exposed to too much humidity, it can lead to cracking. If you live in a humid environment, make sure to store your clay in an airtight container and keep it away from any sources of moisture. You should also avoid using water-based paints or sealants on your finished pieces as this could add too much moisture back into the clay and cause it to crack.

Poor technique

Not following proper techniques while working with polymer clay can also contribute to cracking during baking. Make sure you are working with an even pressure when rolling out your pieces, and not pressing down too hard which could result in cracks when baked. Be careful not to overwork the clay, as this can also cause it to crack.

By taking the time to properly condition your polymer clay and ensuring you are baking at the correct temperature, you can avoid cracking and have a successful finished piece!

Inconsistent thickness in the Clay project

One of the most common causes of cracking in Polymer clay projects is inconsistent thickness. Even a slight difference in the thickness of the clay can cause your projects to crack during drying or baking. To prevent this, make sure that all parts of your project are rolled out evenly and to the same thickness. Additionally, be aware that some areas may need more support than others; for instance, when making a bowl-shaped object, use thicker clay on the curved edges than on the flat bottom. Lastly, try not to handle your pieces too much after they have been shaped as this can weaken them and cause cracking. If you do find yourself handling them frequently, try using cornstarch or talc powder to keep the surface from sticking together.Polymer Clay

If your clay project is already finished and you discover it has cracked, there are a few options available. If the crack is small and not too deep, it can be repaired with a bit of extra clay. Simply fill in the gap with fresh clay, making sure to blend in the edges so that it matches the color and texture of the surrounding area. If you have more serious cracks in your piece, try using super glue or epoxy to fill them. Be aware these glues may discolor your polymer clay slightly, but they should help hold it together while drying or baking.

No matter what changes you make to prevent cracking in future projects, always make sure that each part of your Polymer Clay creation is of even thickness. This way, you can be sure that your projects will come out looking just as good as you planned them to!

Using the wrong type of Clay for a project

Polymer clay cracking can be caused by using an inappropriate type of polymer clay for a project. Each type of clay has its own properties and uses, so it is important to select the right type for a specific task. For instance, Kato Polyclay is a firmer and more durable material than Premier Clay, which makes it better for projects that require strength. On the other hand, softer clays like Fimo Soft are ideal for sculpting intricate details since they are very pliable. Using the wrong type of clay in a project could result in cracks due to the strain placed on the material as you work with it. Be sure to check the manufacturer’s instructions before selecting a clay for your project in order to get optimal results.


In addition to using the wrong type of clay, using too thin or too thick pieces can also lead to cracking. If the piece is too thin, it will not be able to hold its shape while being worked on and may crack under pressure. On the other hand, if the piece is too thick, it will not be flexible enough to conform to your desired shape and could also result in cracks. For best results, make sure that the pieces are neither too thin nor too thick before starting your project.

Finally, improper baking can also cause polymer clay cracking. The temperature and time used for baking polymer clay must correspond with those recommended by the manufacturer for optimal results. If not, then the finished product might be brittle, which could lead to cracks forming. Therefore, be sure to follow all instructions carefully in order to avoid any unnecessary issues.

Not conditioning the Clay properly

One of the most common reasons for cracking clay is not conditioning it properly. Polymer clays come in a block form and need to be softened, or conditioned, before you can use them. This can be done by either rolling, kneading, or slicing the clay until it is soft and pliable enough to work with. If the clay has not been fully conditioned, it will become brittle and is more likely to crack when being manipulated or baked. It’s important to take your time when conditioning your clay so that it has an even consistency throughout.

Using too much Pressure

Another common reason why polymer clay may crack is due to using too much pressure when manipulating it into shapes and forms. Depending on the type of clay, some varieties are more brittle than others and can easily break if too much force is applied. To avoid this, use gentle pressure when forming the clay into whatever shape you desire and make sure that it is conditioned properly beforehand.

Inconsistent Baking Temperatures

The last common reason why polymer clay may crack is due to inconsistent baking temperatures. If the temperature in your oven is not set accurately or fluctuates during baking, then the clay could develop uneven shrinkage in the material which can cause cracks or warping. To prevent this from happening, use an oven thermometer to check that your oven’s temperature is accurate and consistent throughout the baking time. You should also read any instructions included with your type of clay for any additional baking tips.

By following these tips, you can help to avoid any cracks or other issues with your polymer clay creations!

Not allowing the Clay to cool completely before manipulating it

One of the primary causes for cracking in Polymer Clay is not allowing it to cool completely before manipulating it. This especially holds true with larger pieces or when making complex shapes. As Polymer Clay is heated, it softens and becomes moldable, but when removed from heat too soon, the clay can remain in a malleable state. When manipulated while still warm, the polymer molecules within the clay become stretched and distorted resulting in cracks as they cool and harden. To avoid this issue, be sure to always allow your pieces sufficient time to cool down before attempting any shaping or manipulation. Additionally, keep an eye out for uneven cooling which often occurs on thicker parts of the piece and can cause cracks during the cooling process.Polymer Clay

Heating the Clay too quickly is also another factor that can cause cracking. When heated too quickly, the internal structure of the clay can become weakened resulting in cracks as it cools and hardens. A slow and steady approach to heating is always advised when working with Polymer Clay as this ensures that all parts of your piece are heated evenly. Additionally, be sure to avoid overheating which can not only lead to cracking but will also adversely affect the color of your clay.

Finally, when baking Polymer Clay pieces in an oven, ensure that you follow any instructions provided on the packaging or by the manufacturer carefully. This often includes preheating the oven before placing your project and adding a few extra minutes to your bake time for larger or thicker pieces. Not following these instructions can lead to uneven heating and cracking as the clay cools.

By taking into account all of these potential causes, you’ll be well on your way to creating beautiful Polymer Clay projects without any risk of cracking or other issues. Happy crafting!

Mixing different brands or types of Clay together

The most common reason for your polymer clay to crack is mixing different brands or types of clays together. Although two brands may be the same color, they can have very different formulas, resulting in cracking when they are mixed and baked. To avoid this problem, it’s best to avoid mixing different clays. If you must use multiple colors or types, make sure that they are both by the same manufacturer. This will help ensure consistent results in your project!

Also, keep an eye out for any air bubbles that may appear while working with the clay – these can cause cracks when heated too high or baked for too long. Make sure to use a needle tool to pierce any visible air bubbles before baking and reduce the baking time if necessary. Finally, remember to always condition your clay before beginning a project – this will not only help it to remain pliable while working, but also prevent cracking during baking!

By following these tips and avoiding the mixing of different brands or types of clays together, you should be able to avoid most cases of cracking with your polymer clay projects! Good luck and happy creating!

Using too much liquid in the Clay mixture

Polymer clay cracking can also be caused by using too much liquid in the mixture. Using too much liquid in the polymer clay mix causes the clay to become weak and brittle, resulting in cracks appearing during baking or handling. If you are having difficulty combining colors of polymer clay, it is best to knead each color separately with your hands first before mixing them together. This will help reduce the amount of liquids used which can help prevent cracking during drying or baking. Additionally, try not to use too many tools when working with polymer clay as this can add extra strain on the material and cause it to crack. Instead, use your hands or a rolling pin to shape and combine colors.

Another way to prevent cracking due to excess liquid is to let the polymer clay sit for a few minutes before baking or drying. This allows the excess liquid to evaporate from the clay, resulting in a stronger material that is less prone to cracking. Additionally, make sure you are working on a clean and dry surface when using polymer clay; this will also help prevent cracking due to excess moisture in the mix. Finally, try not to overwork your polymer clay as it can become weakened by too much manipulation and result in cracks appearing.

Help! My Sculpture is Cracking! – The Clay Teacher Answers Your Questions

Polymer clay is an incredibly versatile material that can be used to create amazing works of art. However, it’s important to remember that proper care must be taken when handling and baking polymer clay so that it doesn’t crack or break during use. By following the tips outlined above, you can help ensure that your polymer clay creations remain intact and beautiful for years to come.

Not using a sealer or varnish on the finished project

One reason why your Polymer Clay project may be cracking is because you did not use a sealer or varnish on the finished product. A sealer or varnish will help to protect the clay and keep it from cracking over time. Make sure to use a good quality sealer that is specifically designed for polymer clay, as some products can react unfavorably with the material. Sealers apply an even layer of protection, preventing cracks caused by humidity and temperature changes. It’s also important to make sure that the sealer is applied in thin coats; any thick layers can cause problems like bubbling and cracking. Additionally, make sure that you are allowing each coat of the sealer to dry before adding another layer. As long as you apply a sealer or varnish correctly, your polymer clay project should last for many years without cracking.

Applying too much pressure to the Clay while working on it

Polymer clay is a great material that can be used to create all sorts of items, however it can be prone to cracking if too much pressure is applied while working on it. Working the clay too hard or using tools that are too sharp may cause cracks in the polymer clay. Rolling pins and other tools should be used with a light but firm hand to avoid damaging the clay. If you find that your clay is cracking during model-making, try kneading the clay more slowly and gently. This will help reduce the amount of stress being applied to the material. Additionally, reducing changes in temperature when baking can also help avoid cracking. If you have already baked your piece and it has cracked, there are a few solutions available. Applying a thin layer of liquid polymer clay to the cracks can often help fill them in and make them less noticeable. Adding mica powder or glitter to this layer may also help conceal the cracks. If these methods do not work, you may need to start again with fresh clay and try to be more careful when applying pressure during working on it. Remember that it is important to use gentle pressure when working with polymer clay – otherwise, your creations could end up cracking! Happy crafting!

Hope this helps! Good luck. 🙂

The impact of environmental factors such as pollution and UV light

can cause your Polymer Clay to crack. When exposed to these elements, the plasticizers may begin to evaporate and leave the clay more brittle than it was before. Additionally, if you are working on a hot surface or have left your project in a hot car, this can also cause cracking.Polymer Clay

It’s important to note that some clays can be prone to cracking even without environmental factors at play. For instance, Sculpey III is known for being more fragile than other brands of Polymer Clay and therefore may crack easier than expected under normal weather conditions.

There are steps you can take to prevent your Polymer Clay from cracking due to environmental factors. First, store your clay in an airtight container with silica gel packs to help absorb any moisture. Additionally, if you are working in a hot environment, try to find a cooler area or work in shorter bursts of time. Finally, keep your finished project away from direct sunlight and other sources of UV light to reduce the risk of cracking.

Why does polymer clay break after baking curing finishing?

By following these steps, you can make sure that your Polymer Clay stays in top condition and lasts as long as possible. Remember: prevention is better than cure! Good luck with all your crafting projects!


How can I prevent my Polymer Clay from cracking?

Cracking in polymer clay can be caused by many things, such as too much water content, not baking the material long enough, or baking at too high of a temperature. To avoid cracking, it is important to make sure that your polymer clay does not have too much moisture (use a pasta machine to mix and knead for even results). Additionally, ensure that you are baking the material in an oven set to the recommended temperature for the specific brand and type of clay being used. Lastly, bake your project long enough – follow the manufacturer’s instructions on curing time to get the best results. With proper preparation and care, your polymer clay should remain crack-free!

What should I do if my Polymer Clay does crack?

If your polymer clay project has already cracked, there are some ways you can repair it. Depending on the size of the crack, you can try filling it in with fresh clay or using a mixture of baking soda and water to form a paste that can be used as a filler. Additionally, if the cracks have not gone all the way through, you could also use an acrylic sealer to fill in any visible surfaces. With enough patience and care, you should be able to salvage your project even after cracking!

Are there any tips for storing Polymer Clay?

Yes! To ensure that your polymer clay does not crack before you even get to use it, proper storage is key. Make sure that you keep the material in an airtight container or plastic bag and store it away from direct heat sources. Additionally, if your clay has been exposed to high temperatures (due to being left out in a hot garage or car) try kneading it with a pasta machine or rolling pin before using to avoid cracking while baking. With these simple steps, your polymer clay should remain usable and ready for your creative projects!


Cracking in polymer clay is a common problem for crafters, but it can usually be avoided with proper techniques and careful storage. It’s important to know the causes of cracking and take the necessary steps to prevent it. If cracks still occur, there are ways to fix them so that the project can be salvaged. Additionally, make sure to always store polymer clay properly and practice good sculpting techniques when crafting your project. With these tips in mind, you’ll be able to avoid unnecessary cracking and create beautiful projects with polymer clay.

The most important thing to remember is that cracking in polymer clay can be prevented if you take the right precautions. With a few simple steps and some knowledge, your projects can be completed without any issues! So don’t let cracking ruin your clay crafting – follow the tips above and enjoy your creations!