Avoid These 10 Sculpey Mistakes (and other clays, too!)

When I started working with polymer clay, I made a lot of mistakes. (I still do, by the way.) But experience has taught me a few things and here are some mistakes that I no longer make. (These tips apply to all brands of polymer clay, not just Sculpey. Read on if you use any oven-bake clay brand!) Nobody likes to have their work break, burn, melt, get sticky, or fall apart. Ruined projects are disappointing, but it’s even worse when we’ve given things as gifts or sold them to customers only to realize they’re falling apart over time. So whether you’re new to the world of Sculpey, Fimo, and polymer clay or whether you’re an old pro, it doesn’t hurt to take a moment to check these out. Avoid these 10 Sculpey mistakes and spend more time enjoying your work with polymer clay.

1. Using Weak Polymer Clay for Thin Pieces

Underbaked polymer clay will crumble. How long to bake polymer clay? Read more at The Blue Bottle Tree.It is so sad to work hard creating something that breaks when it’s worn or used. It’s even more horrifying to realize that you’ve sold something that is made from weak clay and won’t be durable. Not all polymer clay brands are created equal and each has its uses and purposes. For making things that are thin or have areas that are thinner than 1/4″ (6mm), make sure that you’re using a strong clay such as Premo, Fimo, Pardo, Kato, Cernit, or Souffle. Sculpey III, Original Sculpey, Super Sculpey, and Bake Shop are all quite brittle after baking and should not be used, unsupported, in any area thinner than 1/4″ (6mm). These weaker brands do have their uses, however, so save them for other projects. Here’s more about choosing the best brand of polymer clay for your project.

The stronger brands of polymer clay are durable enough that you cannot break them with your hands, even when used as thin as 1/16″ (1.5 mm). Of course to have this kind of durability the clay must be properly baked, which leads us to the next point.

2. Underbaking Polymer Clay

Polymer clay is made from PVC powder, plasticizers, binders and fillers, lubricant, and pigments. As the temperature increases during curing, the powdered PVC softens in the plasticizer and the particles begin to absorb the plasticizer. Optimally, the particles will eventually fully fuse together and form a solid mass of plastic. If polymer clay is underbaked, the fusion will not be complete and the resulting clay mass will be weak. Underbaked clay is not only less flexible, it is susceptible to breaking and crumbling. Underbaked polymer clay can also have excess free plasticizer that can lead to cure inhibition in paints and glues, causing them to remain soft and/or sticky.

To properly bake polymer clay, you must consider both time and temperature. The temperature on the package is a guideline, and you do have some leeway. But you really do need to bake at a sufficient temperature for at least as long as the time stated on the package. Most ovens are inaccurate and it’s important to use a separate oven thermometer to know what temperature your oven actually is. (I like this inexpensive digital probe thermometer, but there are many others.) In the real world, even accurate ovens fluctuate during the baking cycle (and when you open the door). It’s therefore best to bake quite a bit longer than the label suggests to make up for this.

Use oven thermometers to verify the temperature of your oven when baking polymer clay. Most ovens lie.
I use two digital probe thermometers to verify exactly what temperature my oven is during baking. I’ve been quite surprised to see that my oven’s dial is often off by 40°F or more.

Polymer clay should be baked for at least 30 minutes for each 1/4″ of thickness. This means that a 1″ thick bead will need to be baked for two hours. Yes, this is correct. If your oven is truly baking at the correct temperature, your clay will not burn. Lighter colors may, however, discolor, so it is always better to do multiple bakings of thinner layers. Want to learn more? Here’s my class on baking polymer clay that gives more info about choosing an oven, baking temperatures, and knowing if you’ve baked your clay long enough.

Burned and blistered polymer clay is a result of using an oven that heats to the wrong temperature. Learn more Sculpey Mistakes to Avoid at The Blue Bottle Tree.

3. Burning Polymer Clay

Let me be very clear. Polymer clay does not burn unless it reaches temperatures near 350°F (176°C). (Fimo is a bit more sensitive.) If your project actually turns black and bubbles, then your oven is way too hot! As already state, ovens can be wildly inaccurate. When the oven’s heating element cycles on and off, the heat radiating from it can be tremendous. If your project is close to the element, your thermometer could be reading the correct temperature but your project could still bubble and blacken. If you have burned polymer clay, you need to address your oven, not your baking times.

Many people assume that baking longer times at lower temperature settings will solve this problem. It’s common to read recommendations in forums to set your oven to, for instance, 215°F (100°C) and bake for an hour or so. Will this work? Well, it might work for a specific person because they’re compensating for an incorrect oven. What they think is 215°F might actually be 275°F in their oven. But when others follow this temperature advice, they end up with fragile, brittle, underbaked clay.

Light colored or translucent polymer clay will commonly discolor and darken during baking. This is not the same thing as burning. To prevent this, first make sure that your oven truly is baking at the correct temperature. Then cover your pieces to prevent the oven’s element from toasting your polymer clay project. For more info on covering clay and preventing browning, see my class on Baking Polymer Clay.

4. Using Nail Polish as a Polymer Clay Glaze

Are you making these 10 Sculpey Mistakes? Learn more at The Blue Bottle Tree.It’s very common to see polymer clay projects, especially on craft blogs, that recommend using nail polish as a glaze or gloss finish on polymer clay. It’s convenient, it’s simple, and seems like such a good idea. Except that it’s not. As many, many people have found out, nail polish on polymer clay will very often turn sticky and goopy over time. Not all nail polishes are bad. Some work just fine. But there are thousands of brands of nail polish around the world and there is really no way of knowing which ones will work on which brands of polymer clay. Don’t risk it. Use a proper polymer clay sealer. If you need to use one at all. Yes, that’s right. You don’t actually NEED to seal polymer clay. Read more and learn which sealers are the best to use when you do want to use one.

5. Using a Spray Varnish on Polymer Clay

Do not use Krylon Crystal Clear Glaze on polymer clay because it will turn sticky over time.

It also seems like such a good idea to buy a can of spray varnish and give all your newly made Sculpey creatures a nice glossy coat of spray varnish. So simple and so easy. Except that the varnish never dries. There are very few spray varnishes that are compatible with polymer clay. And what works with one brand of clay won’t work with another. I tested many brands of spray sealer on polymer clay and only found two brands that consistently works with all brands of clay.

What if you’ve used a spray sealer and now your charms are sticky? Can they be saved? In some cases, yes. I found that 91% isopropyl alcohol removed most sticky spray sealers. It’s worth a try.

6. Storing Polymer Clay in the Wrong Plastic

Polymer clay is vinyl that contains a plasticizer to make the finished pieces more durable. That same plasticizer also softens other plastics, too. So there are some plastics that will be dissolved when left in contact with polymer clay. Because of this, you need to be careful to only store your unbaked polymer clay in containers that are compatible with polymer clay. Avoid using anything with recycle number 6 or 7 on it. Avoid contact between raw polymer clay and anything made of styrene, polystyrene, styrofoam, and ABS because it will soften and fuse with the polymer. This also means you should avoid contact with keyboards, Lego, many toys, and Bic Cristal pens, and those clear hard plastic pots that lip gloss or eye shadow comes in. The clear, brittle plastic storage boxes are a no-no, too. Learn more about polymer clay melting plastic in this article.

You can generally store unbaked polymer clay in plastic ziploc bags and any plastic box with a 1, 2, or 5 on the bottom. The floss box below works very well.

7. Not Washing Your Hands Before Working With Clay

Dirty hands make working with light colored polymer clay difficult.Related to the dust issue is one of making sure that your hands are clean before working with polymer clay. Even when you think your hands are clean…they’re not. And when working light colors such as white or yellow, or translucent, dirt that’s invisible on your hands can end up in your clay, giving your work dirty streaks. Even the blue residue from wearing blue jeans will coat your hands and show up on light-colored clay. So before working with polymer clay, wash your hands well, and don’t forget to clean under your fingernails.

Another trick is to have a ball of scrap translucent clay at your work desk. Roll this clay between your hands before working. It will pick up any loose skin bits, fiber, dirt, and dust. It’s also a great trick to do when switching from working with a dark color to a light one. When the clay gets too junk-filled, just toss it and make a new one.

8. Buying Too Many Tools…At First

It’s all too common for a newbie to find out about polymer clay and buy everything in the clay aisle at the craft store, assuming that it’s all required for working with polymer clay. Not only can this be very expensive, but you really don’t need most of the tools you’ll see for sale there. Start with some basics, then add more as your experience grows and you have a better idea of what you like to make.

There are plenty of polymer clay tools out there, and you want to leave enough money (and space) so that you can buy the things that will bring you the most enjoyment. So, what are the essentials? Here’s what I recommend to buy for your Polymer Clay Starter Kit. And when you do start buying tools, you can often find them quite cheaply when you start looking in creative places. Here’s more about finding cheap polymer clay tools.

9. Embedding Eyepins Without a Kink

When you make polymer clay pendants and charms, you’ll want to include a hanging loop. A lot of clayers take a commonly available jewelry eyepin, cut it to length, and insert it into the raw clay. But after baking, the straight wire of the eyepin readily pulls out of the clay. Some people glue the pin and push it back into the baked clay. That will often hold, but not always.

A better way is to create a small kink in the end of the eyepin, before you embed it into the raw clay. This way it cannot pull out after baking. Here’s an example of what I mean:

Always put a kink or bend in your eyepin before inserting it into polymer clay. Avoid these 10 Sculpey Mistakes.

10. Using the Wrong Glue with Polymer Clay

Superglue is magical and it can be an incredible glue in the right circumstance. But it’s not the best glue for polymer clay. At least not the usual inexpensive superglue that we all know and love/hate because the cap gets glued on (so frustrating). It is a very brittle glue and polymer clay is flexible, so when the clay flexes, the hardened glue will pop right off and the bond fails. It’s better to use a gel version such as Loctite Gel Contol or a higher end version such as Lisa Pavelka’s PolyBonder.

Cheap super glue is one of several popular glues that don't work well for polymer clay. Avoid these 10 Sculpey Mistakes, read more at The Blue Bottle Tree.

Another often recommended glue, especially for jewelry use, is E6000. While it can be a very good glue for some uses, it does tend to remain gummy never and fully harden on polymer clay. Many people DO have good results, but many others do not. I suspect the issue lies with the brand of polymer clay or perhaps the age of the E6000. But don’t be surprised if you find that this glue fails for you.

It’s always better to use a physical bond or a baked bond to glue polymer clay to itself or to glue metal to polymer. For more specific recommendation and glue strategies, visit my article What’s The Best Glue for Polymer Clay.

Email is the best way
to get updates

You will LOVE getting this email, which is packed full of polymer clay goodness. About once a week.

Share on facebook
Share on pinterest
Share on vk
Share on whatsapp

160 thoughts on “Avoid These 10 Sculpey Mistakes (and other clays, too!)”

  1. Hi Ginger!
    I recently made a practice piece pendant out of Sculpey III that turned out really well. I want to give it as a gift, but being aware that it might break (some of the parts are less than 1/4″ thick and stick out on the sides about a half inch) I want to know if coating it with a resin will help strengthen it. I’m also considering placing it in a coaster mold and filling it half way up with resin to encase the exuding pieces to ensure they don’t break off. Have you ever experimented with a project like this? It’s very detailed and took me a long time to make, so I’m reluctant to just start over with a better clay! Any ideas or thoughts you have about how to strengthen (or shore-up) the fragile areas would be very much appreciated. FYI: it’s a lion with a frilly mane, and it’s about 3″ in diameter, so the mane will most likely catch on things. The bake came out fine, but I’m reluctant to put any pressure on the areas that I know are weak until I find a way to strengthen them first.

  2. Will polymer clay work for all-weather, permanent garden markers? If yes, what brand would you suggest? and thank you so much for all your great advice.

    1. Yes, it works very well. You can use any brand, but the premium brands will be more durable. Be sure to skip any surface treatments or varnishes. Just use the clay. Be aware that some colors may fade in direct sun over time. But the clay, itself, holds up great.

  3. Hi! This is a great article, thanks. I wonder if you could give me some thoughts. I carefully baked my polymer clay at 130c for 15 minutes as per the instructions for sculpey III. Its still brittle and breaks if I try to flex it as I have seen others do with baked polymer clay. Is it because I’m using sculpey III and not a better brand? The oven is brand new so I’d hope its pretty accurate. I got the impression from your article that perhaps sculpey III doesn’t flex like the other better quality clays. Thanks so much.

    1. Sculpey III is quite brittle and will bread easily, yes. It is not as strong as the others. But it still should take some effort and intentional action to break it. It’s still a good idea to get an oven thermometer to verify what your oven is doing. Also, 15 minutes might not be enough, especially if the oven is underpowered, if the oven door was left open for long, or if you baked on a tile. For more baking info, please check out my baking tutorial here: https://learn.thebluebottletree.com/product/baking-polymer-clay/

  4. Roxanna Kilpatrick

    Quick Question: When you put kink at end of eye pin then insert in clay, doesn’t it mess up the project? Is there a tutorial for this?

  5. Hello, I wanting to use sculpey III for sun catchers. The sculpey shapes will be attached to chain along with crystals and beads resulting in a single long chain. My worry is, will the sculpey be strong enough. The shapes will be flat.

    1. Depends on how thick they are and how well you bake the pieces. Also, Sculpey is a brand name, not a specific kind of clay, so it would also vary based on which of Sculpey’s clays that you would be using.

  6. Will anything go wrong if I don’t pre-bake liquid polymer clay molds before I put the liquid clay in the molds and bake it so that it is solid?

    1. They do recommend warming the molds first. I suspect this has to do with bubbles, but I am not sure. Give it a try. The best process is always the one that gives the best results. Give it a try to see what works for you.

  7. I just noticed that when I bake my Sculpey Premo and Soufflé between two ceramic tiles at the correct time and temp, after baking, if I bend my pieces with pressure they snap in half. When not baking between two tiles, however, they are more flexible after baking at the same time and temp. Any ideas?

          1. Hello, thank you so much for this article!
            I tried baking Sculpey iii for about 1 hour at 130c but it was still really brittle and would not flex. When I tried drilling holes in it, it would break in half. Am I baking it wrong/is there something wrong with the temperature or should I use Premo instead for making things like earrings?

  8. Hi,
    I’m using premo for my projects. And once baked everthing is cured well. But when I use white blanco liquid or tlc with clay n bake after 2 days cracks start form. Can I know, Where am i going wrong here pls

  9. Hello I’m just wondering I’m using a premo beige clay and after I bake it and wear it- the charm starts to colour – like the colour of my clothes rub off on it? Have I not baked it long enough? Even a red charm I made – I was wearing it day and night and after a while it was discolouring – not sure if it’s oils from skin or clothing? Any ideas?

  10. I’ve been making things with clay for years, never had one crack after baking until last night.. then this morning.. sooooo frustrating seems after it comes out of the oven and starts to cool it’s cracking?! What am I doing wrong.. cooked at 275 for 45 minutes, maybe not long enough? I normally do an hour for my pieces that are all roughly the same size and they didn’t crack, I was concerned with over baking but now I’m reading it’s not really possible to over bake? The only other thing I’ve done different is make a bunch of my shapes and store them in a styrofoam food container and then work on one piece at a time could that be a problem? I normally make my shake and work on it until finished, bake it and move to the next but I’m trying to be more efficient with my work, any advice?

    1. Cracking that happens during (or directly after) baking is not the same thing as breakage and has very different causes. There are dozens of reasons why cracks might form in your item. Some common reasons are when a piece is too thick (typically thicker than 3/4″), when you stretched the clay as you made it, or sometimes it’s just the specific batch of clay.

      I wouldn’t store your unbaked pieces in styrofoam. I’m surprised that worked for you. Styrofoam is dissolved by polymer clay and will melt right into it.

  11. I have been making some dolls with polymer hands, feet/shoes and heads, but the hands have been brittle and fingers snapped off, but noses and toes don’t. I have been baking as recommended at 100 deg for 30 mins, using Nara, Fimo and Sculpey, and without realising, Sculpey 3, and all have had similar results with the hands. After reading your experiences I have ceased all doll production and ordered a thermometer for my oven, a fan forced one, to see what has been the problem. I would like to hear from anyone who may have been underbaking thinking they were OVERbaking, which is where I thought I was at. I have watched some other Youtube sites and seen that I am supposed to expect flexible results, but not ONCE have I had anything come out remotely flexible.

  12. I’ve been using Kato clay on wooden dolls to sculpture hair and such. I’ve found that after baking for 30min the clay is firmly set but also very smooth and doesnt take the acrylic paint. very well. Is there a trick to painting clay? Have I just overbaked it? Would love to hear your thoughts on painting clay.

  13. I live in Korea so brand recs might not be easy to find. I want to do a project with my kids. Do I have to bake the clay when finished? Or can I just seal it with something when they are finished? Also if my kids are adding on bits and pieces to something (we’re going to try to make pokemon) so they need to glue the pieces or can they just press on and wait for it all to dry? Thank you.

  14. Thank goodness I found your website before finishing my first “serious” clay project!
    I am working on very thin and tiny things like flowers with separated petals and such. Which polymer clay would you say it’s best for things like these? Some will go inside glass bottles, some probably won’t.
    Thank you for sharing your knowledge. It’s worth gold for people like me!

    1. The most durable brand is probably a tie between Cernit or Souffle. But it must be baked long and hot enough for optimal strength. Usually an hour at 275F/135C will do it. Another clay to try would be Prism & Pro (available on AliExpress). It’s very strong and break resistant.

  15. Chiara Mallamo

    Could someone please tell me if I can bake my polymer clay with findings in it? Ie, if I want to insert my screw in eye pin before baking then put it in for baking. Or will this damage the metal?thank you

  16. I make earrings and I’ve been using premo III and I thought it was me ! Everything was breaking everything was brittle I hated it I still do. I ordered the igloo soufflé i hope it’s better ‍♀️

  17. I have cooked my Premo polymer clay at 275 all the way up to 350 for over an hour and my pieces are still breaking I have a thermometer in my oven and I know my oven is cooking properly what is wrong

  18. Allison Van den brand

    So i baked my pieces and they are very firm and not bendy. I’m afraid of their integrity as earrings and i want to sell them but don’t want them to crumble. Can i rebake them some more or now that they have baked and cured will they burn?

    1. Rebaking won’t burn them as long as the temperature is correct. It won’t, however, give much improvement in strength. If they’re not crumbling now, they won’t crumble later. Give them a good flex…they should withstand it. If not, and they break, then you’ll know. Not the best solution, I know. But it’s better than selling weak product. In the future, make sure that you bake the full duration all in one go, the first bake.

  19. My last round of sculpey baking seems to have let off more fumes then usual and a few bright orange pendants seem darker. Does this count as burning? And are you supposed to clean your oven after this before you use it for food?

    1. No, burning is burning. The clay will bubble, turn black, and give off smoke. Darkening is often just a normal consequence of baking, depending on the color. While there is an odor, these are not dangerous “fumes”. You’ll know when you burn your clay. It will be unmistakable, LOL.

  20. Thank you for your guidance! When I bake my clay, it comes out kind of like plastic. It seems when I used clay years ago, it came out more like bisque, kind of chalky like feel.

    1. I do alot of craft shows it being summer my crafts melt until i get them in a cooked area how do i prevent this.

  21. I have Sculpey III,I got it as a gift and it’s my first attempt at polymer clay. I want to do a figurative sculpture using an armament. Will a cardboard tube not work because of the air inside? Do you just make them of tightly packed tin foil always or can you use other things like newspaper?

    Also: I have model train Testors paint, and watercolor paint. Will either of these work with the cured Sculpey III?

    Thank you so much for the great resource 🙂

    1. A cardboard tube will work, but you need to leave an escape hole so the air trapped inside doesn’t expand when hot and break the sculpture. As for paint, neither of those will work. Testors will get sticky, and watercolors will not stick.

  22. Ok I have a question about the wire… I baked a piece about 30 minutes, let it cool, inserted a metal pin which I secured with some uncured clay. I baked another 30 (at low temps) and it exploded! The cured clay was ripped open. Do you know why this could be? I’m so confused!

    1. Hello. I use Super Sculpey to make figurines. I make the heads first, but I’m finding each time they come out of the oven they are full of what appear to be chips in the clay.
      I bake at 130 degrees c for 30 minutes, they have a foil ball centre.
      I hand condition the clay first.

      Any ideas on what is going wrong?

      1. These are tiny air bubbles in the clay and you can see them due to the slightly translucent nature of the clay. Be more careful to avoid trapping air as you work. These can also be a result of humidity in the clay.

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top



Check your email


Confirm your email


Get secret stuff

Sign Up Here

There's more by Email.

Keep in the loop about new articles and tutorials. Get tips and info. Weekly emails, or thereabouts. This is the newsletter that everyone talks about.

The website uses (electronic and non-edible) cookies to allow items to stay in your shopping cart, to eliminate banners you've already closed, to allow the social media share buttons to work, to allow you to log in and access your account, and anonymously to analyze traffic. Only anonymous data is shared with other services. You consent to these cookies if you continue to use this website. Thanks!