Baking Flat Polymer Clay Sheets – Avoiding Common Problems

Polymer Clay Gingerbread Cookies

Photo shows baked polymer clay gingerbread cookies with unwanted texture caused by uneven heat:

The other day a reader submitted this question: “Hey Cindy – Attached is a photo showing the texture of the baked polymer clay I was talking about. Is it bubbling that has occurred? How do I prevent this? I’ve noticed it happens to my thin products. Thanks, Rae.”

Thank you Rae, for sharing your photo and describing the problem. This used to happen to me all the time. No worries though. I’ll tell you how to prevent it from happening next time you bake your flat polymer clay cookie pieces.

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Clue #2 >> Sanding Polymer Clay

First of all, I am assuming your photo is showing the backside of your gingerbread men / women (hard to tell what their gender is at this stage :). I am also guessing you baked them on a metal pan or cookie sheet.

When thin flat pieces of polymer clay are baked on metal sheets, the metal heats up unevenly and air gets underneath the clay. This causes little “pock” marks, textures and shiny spots on the clay during the baking process. In this case, your clay did not have air in it, but rather under it. Think of what the back of a ‘real’ gingerbread man looks like after baking… very much the same.

To prevent this from happening, the clay needs to have full contact with the surface it is baking on and it needs to be baked more evenly.

In my bead making course video #37 on baking polymer clay pendants, I show how to place your flat sheet of clay (in this case your gingerbread people) on a piece of paper card stock; Followed by placing that card stock on a smooth surfaced ceramic tile. The paper gives the clay a nice smooth surface to stick to and the tile helps evenly distribute the heat.

To add extra weight and keep everything nice and flat, a piece of parchment paper is placed on top of the polymer clay and another tile is placed on top of that. Make sure to put the smooth sides of the tiles next to the clay rather than the backside of the tile which often has rough ridges.

This sandwich (bottomtile / cardstock / polymerclay / parchmentpaper / toptile) is then placed into the oven to bake. Make sure to add extra time for baking because it is harder for the heat to penetrate all these layers. I bake my pieces for at least 1 hour at the recommended clay manufacturer’s temperature.

After your pendant or polymer clay gingerbread cookie is fully baked, let it cool before removing from the tile sandwich. This will make sure your flat pieces stay flat during the baking process. You will see a huge difference if you bake your flat sheets of polymer clay following these instructions and techniques.

As far as the clay gingerbread people that are already baked, all is not lost. You can easily smooth off the rough surfaces with drywall sandpaper. To learn more read my post about using drywall sandpaper on polymer clay.

I hope that helps you Rae and everyone else that has experienced this problem with baking flat polymer clay sheets. You can let me know if this information was helpful by leaving a comment below.

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  1. Cindy Lietz, 01 June, 2008

    If the backside of your pendant or piece is smooth but the topside is dimensional, you won’t be able to lay the second tile on top. Just make sure your pendant is firmly seated on the card stock so that the whole surface is touching the paper before placing on the tile to bake. To further protect your pendant, ‘tent’ it with a folded piece of parchment paper to keep it from scorching.

    Cindy Lietz’s last blog post..Polymer Clay Tools for Softening Clay Quickly

  2. Lani King, 18 July, 2008

    Thanks! Now I won’t ruin any flat pieces I make. -Lani

  3. Lani King, 18 July, 2008

    This is on the treasure hunt twice. -lani

  4. Krista, 18 July, 2008

    I would imagine just like any other item baked, placing it on a card or parchment paper will also keep any shinny spots off of it. I never thought about making gingerbread people with clay…I think they are cute, no matter what gender they are…or aren’t! = )

  5. Cindy Lietz, 18 July, 2008

    Lani – What happened is that you stopped looking for Clue #3 as soon as you found Clue #2 again. Click on the Clue #2 link again [Polymer Clay Finishing] and keep searching for Clue #3. It’s there :-)

    Cindy’s last  post..Flower Beads for Jewelry Making, Created from Polymer Clay Canes

  6. Tina Holden, 18 July, 2008

    Great article Cindy! Personally I love cardstock and tile method to keep things flat and to avoid shiny spots or sometimes I’ll use printer paper if weighting it down with another tile. I’ve had mishaps with Parchment as it tends to wrinkle with heat, at least the stuff I’ve used. This treasure hunt is fun, but I don’t really need to win a treasure, you’ve got all sorts of treasures on every page! :)

  7. TK, 18 July, 2008

    Woo hoo! I knew about baking on paper (THANKS to Christie Friesen for that tip!) but never thought to make a sandwich. My flat pieces will look sooooo much better!

  8. Cheryl, 18 July, 2008

    That was great. I’m new to polymer clay and need all the help I can get. I will be trying that. Thanks, Cheryl

  9. Brenda Estes, 18 July, 2008

    I heard once that a person could use batting like you put in a quilt to bake your items on. I burn enough clay as it is to think about catching my oven on fire with quilt batting. You got to remember it is still in the back of my mine. Think heaven my son is a fireman! LOL!! Thanks for the idea about the tile sandwich. I will have to put this in my notes.

  10. Karen Orton, 18 July, 2008

    Well, not only am I learning about polymer clay baking, but how to possibly fix my cookies as well! Never thought about why that happens. I love to cook, have actually catered from time to time, so I am learning not only about about clay, but cooking as well. I knew there was a reaon I found this website. Would love to know how you figured this out. What a guru!

  11. Sue, 18 July, 2008

    My primary interest in using polymer clay is to create beads for jewelry, but this article has sparked an interest in flat pendants, as well. I never would have thought of putting cardstock in the oven! Home Depot here I come, for drywall sandpaper and ceramic tiles – I can’t wait to experiment with this new idea! Thanks! Thanks also to the readers who posted some additional tips here!

  12. Kam, 18 July, 2008

    Using ceramic tiles to help avoid problems with baking flat pieces of polymer clay is something I have not yet encountered (told you I was new to this!!). And know I can fix it before it happens!! YAY!!!

  13. Sandra Henry, 19 July, 2008

    another idea for using paper if you want a design in your work try adding texture paper. Lay your pieces on front side of your work, laying down on the texture paper than a piece of tile smooth side down on the back of your piece. Even thought I am new a Polymer Clay and I have not yet tried this. I am sure the worst thing that can happen is that it will not turn out. The what if factor, always keeps creeping into my head. Just think where would we be if Judith Skinner did say to herself what if.

  14. Mary Clare Stazzoni, 20 December, 2019

    I’m right there with ya, Sandra! My head races with ideas all day long. Something like this: I see something outside that sparks my interest & already I have a new design idea for a polymer clay project! I love the texture paper idea. thanks for posting.
    happy clayin’
    Mary Clare

  15. Kim C., 19 July, 2008

    I’m in the same boat as tk. I knew about putting it on cardstock but I never thought about the sandwich. I haven’t really had a chance to encounter the problem either as most of my pendants are thick enough not to get the problem described.

  16. Angela, 19 July, 2008

    This one was a BIG help :) My “bubble” art work I turn and make it look as if I ment to do it…not always easy! Look…it is underwater…can you tell? Not any more, this article will come in very handy. THANKS!

  17. ~~~~~Alli ~~~~~~, 19 July, 2008

    thank you!!
    i tried to make flat pendants but they all turned out “bubbled”
    i will deff try this

  18. Garnie, 19 July, 2008

    The “tile sandwich” is a good idea (more “food” for including in the RecipeBox,ha)…was reading on craftygoat’s blog where she used cornstarch smoothed onto tile. Said it helped eliminate air bubbles..? But I like this ideaa of using tiles…no messy cleanup :)

  19. Kriss Johnson, 19 July, 2008

    good thoughts on baking thin clay. I have done this and it really works.

  20. Cindy Erickson, 20 July, 2008


    Thanks for the great idea to insure no air bubbles on my future flat pieces. I am sure that this new “tile sandwich” method will save me many headaches!

    This is just another great example of how “YOU learned by YOUR mistakes…now I don’t have to.”

    I think back now to hearing my metal pans popping and making buckling sounds in my kitchen oven as I baked cookies. It only stands to reason that this would happen while baking clay on a metal sheet as well :) But of course, I didn’t even think of it!

    Thank you for saving me from having to learn from MY mistakes…and letting me learn from YOURS!

    Sincerely, Cindy Erickson

  21. Cindy Lietz, 20 July, 2008

    I am loving all these great comments guys! I love how you all are responding to each other and building a polymer clay community. I hope you guys keep this up after the contest is over, it really helps if we can all learn from each other!!

    Cindy Lietz’s last blog post..Spider Jewelry and Beads

  22. Annie Jones, 21 July, 2008

    Thank you for this article. I was trying to make my son in law a pendant celebrating the upcoming birth of his and my daughter’s first child (a girl). I had trouble getting it off my tile and it would stick. After using card stock to put it on I created a pendant for him that has his name on one side and then used liquid clay to write my granddaughter’s name (Aubrey) on the other side and baked it without any problems.

  23. Cynister, 21 July, 2008


    Great tips here. As usual, I have some follow-up questions for you… :) I’ve heard before about baking directly on tiles, but never on cardstock on top of the tile. What is the difference? Relating to that, if you were to bake directly on the tile, you would need a non-textured, glazed ceramic tile right? I’m having problems finding single tiles like that in sizes larger than 6 inches.

    Last question, if you sandwich the clay before baking, won’t that flatten the thickness of the clay a bit? When baking flat pieces, I’ve sandwiched using a glass pan but only after baking while it cools to prevent curling.

    Thanks again!

  24. Yvonne, 22 July, 2008

    Wow Cindy, I feel like such a Daaaaaa, never thought about putting another tile on top and let it cook a little longer. Great no more curled edges. Think I will invest in a few more tiles of different sizes that way I won’t tie up my main working tile. So much info in your articles.

    Thanks once more

  25. Cindy Lietz, 22 July, 2008

    Thank you all for your great comments! I feel great about them!

    Cynister, the cardstock kind of sticks to the clay but doesn’t heat up unevenly, so the back stays super smooth.

    If you use thicker cardstock it doesn’t matter as much if the tile has a little texture on it because it won’t show through.

    Also a smaller ceramic tile isn’t that heavy so it won’t squish your piece thinner.

    The glass pan idea works but the tile works a little better.

    Cindy Lietz’s last blog post..Faux Amber Jewellery from Polymer Clay

  26. Sue Castle, 23 July, 2008

    Wow, the drywall sandpaper is a new trick for me and a great tip. Thanks, Sue C

  27. Linda Grow, 23 July, 2008

    Hi Cindy this is a great tip. I have always used a tile to bake on but didn’t use the paper until a while ago. Although I already knew about this idea it is nice that you have posted it here for others who didn’t know it yet. Also I wanted to tell Cynister that I got my larger tile pieces (8×8 + 12×12) by calling me local flooring company. We live in a small town so there is only too but anyway they had some that was left over from a job and just gave them to me. You might want to check that avenue out. Good luck.

  28. Marianne Huber, 24 July, 2008

    I would not have thought that paper of anykind would be safe in the oven. Now, I have to get some tiles. More on my shopping list. I already have cardstock. whooppee
    I am going to go to Amazon and get the book that you recommend in you faux amber blog. Amber is one of my favorite stones or gems(I am not sure what it is considered). I can’t imagine how it can be made of clay.
    Thank you again,

  29. Cindy Lietz, 25 July, 2008

    @Sue: You’re welcome!

    @CraftyLinda: The paper is a great trick, isn’t it? Thanks for passing on your tip for getting large tiles!

    @Marianne: The paper doesn’t even brown at that low temp. Be very careful not to let it hit the elements or the sides of the oven though, that will make the paper burn! And here’s the link to the book on faux amber if you want to check it out: Polymer – The Chameleon Clay

  30. abby, 26 July, 2008

    I just recently made a clay mosaic & it was starting to bubble up because the clay I embedded the previously cooked tiles into was very thin and started to bubble so I quickly placed a piece of parchment paper & a ceramic tile on it to flatten it back down & it worked. so next time I cook a thin piece I’ll put the tile on before I bake it & not at the point were it was almost to late. Thanks to you advice.

    thank you

  31. Pepper, 27 July, 2008

    What if we used the embossed wall paper to bake on as well as texture? Then we could cover a piece of cardbord with the paper and use it as a ‘background’ for a display or as a pendant on a greeting card?!?

  32. Marianne Huber, 27 July, 2008

    Cindy FYI, Amazon is not selling the “Polymer – The Chameleon Clay” book any longer. Maybe it is out of print. You have to buy it for the outside sellers and the price runs from #11.91 for used to $30. And $13.97 for new to $43.24. I just found that totally interesting on that great price range.

  33. Jeanie, 28 July, 2008

    Cardstock in the oven, wow it works great. Also we found some 12×12 marble on sale at the local Lowes store that works great for the work surface. Its nice and heavy and doesn’t move when you try to roll or trim your clay.

  34. Cindy Lietz, 29 July, 2008

    @Pepper: Great idea! Textured wall paper would work really well!

    @Marianne: That’s too bad about the book no longer being in print. Means those who want it will have to act quick!

    @Jeanie: Great Tip! Anyone else that wants to use marble tiles for work surfaces should look for ones without the veining or pits so they don’t leave impressions on their clay.

    Cindy Lietz’s last blog post..Slicing Fimo Nail Art Canes | Sculpey Polymer Clay Cake Toppers

  35. Cindy Lietz, 29 July, 2008

    Great tip as well Abby! It is always nice when you can save something you’ve worked hard on!!

    Cindy Lietz’s last blog post..Slicing Fimo Nail Art Canes | Sculpey Polymer Clay Cake Toppers

  36. MJ, 31 July, 2008


    Have used tiles since starting with PC. Will use sandwich idea when making flat pieces (haven’t made any yet).

    Have used quilt batting which cushions the piece, however it turns brown (no effect on the piece) and can stick to the clay but is easy to remove.

  37. Marijke, 01 August, 2008

    Going to try the sandwich method! I already put my flat pieces on a tile, but putting them between two tiles must give a better result.
    Making flat ornaments, one problem keeps returning. If the pieces are to thin, they break easily. Are there ways to reinforce polymer clay? Maybe you do have tips or solutions.

  38. Cindy Lietz, 02 August, 2008

    @MJ: Yeah quilt batting can work pretty good, though I find it leaves little squiggly lines on the beads.

    @Marijke: Baking the thin pieces for an hour instead of a half hour will help with strength. You can put a piece of mesh screen in between two layers of thin clay to make it stronger as well.

    Cindy Lietz’s last blog post..Dragonfly Pendant Jewelry Necklace – Fimo Rubber Stamping Techniques

  39. Kody Kalist, 02 August, 2008

    The sandwich method seems to be a great solution, and I believe it bakes the clay more evenly.
    If one is using a tile underneath, it is conducting heat from only 1 side. Now, with your method, it will be be getting heat from both sides, along with keeping it flat.
    You have invented the polymer clay convection oven!

  40. LisaG, 02 August, 2008

    This is the best place for a wealth of information.
    I had heard about baking on ceramic tile, but not about the sandwich method, but it makes total sense, and hey that says alot about your awesome tuts… if I can understand them, then they are keepers for sure.
    Speaking of sandwiches…….

  41. Linda, 03 August, 2008

    Cindy, I am so glad you made all these wonderful mistakes for all us frustrated newies to learn by!
    It is also learning in reverse if I want to create bubbles for an abstract arty peice. I am learning so much by going through the other hints to find the treasure chest, clever idea this hunt. I’d love to win the prize and learn even more, polymer clay tutors are few around here and nowhere near my home, so I spend heaps of time looking at your site.

  42. Pamela Reader, 04 August, 2008

    oh! Good Grief – is that what all that popping and groaning noise is from inside my oven. Gingerbread people going wrong! Seriously, this is the best tip for a newcomer such as myself. I have worried and fussed over my oven until I have driven my husband, two dogs and a cat completely bonkers! One hour? I’m off to Home Depot to get a couple of tiles and come back to bake. My husband is getting hungry! LOL

  43. Cindy Lietz, 04 August, 2008

    @Kody: Cool thing to say! I guess the two tile really are like a polymer clay convection oven!

    @LisaG: Thank you!! Now go grab a sandwich and get back for more tutorials!

    @Linda: Making the air bubble on purpose for the sake of art, sounds like a very fun idea!

    @Pamela: I’m glad you’re excited! Don’t forget to feed your hubby… you may need him for sanding later! ;-)

    Cindy’s last ost..Faux Turquoise Jewelry Bracelet – Polymer Clay Bead Making Projects

  44. Freda, 05 August, 2008

    Now I’ll know how to bake those flat Christmas cookie tree decorations. They will look so good on our Christmas tree.

  45. Cindy Lietz, 05 August, 2008

    Can’t believe that it is almost time for us crafters to start thinking about what we’re going to make for Christmas presents! These would be an excellent choice!

    Cindy Lietz’s last blog post..Memorial Jewelry – How To Make Rose Petal Beads with Polymer Clay

  46. daisy, 10 August, 2008

    I had not thought about using tiles to keep my clay flat but I did find another way simular to this I use 2 flat ovensafe plates in place of the tiles and have found that it works great. I had tons of “bubbly” pieces before I tried something other than metal to bake on. I wish I would have had this website 7 years ago. lol

  47. Cindy Lietz, 10 August, 2008

    Daisy what an excellent idea! Makes me happy to hear you found your own solution!

    Thanks for your kind words. Having problems myself is exactly why I set up this website and blog. If I can save someone the hassles I went through, I feel like I’ve done a good job.

    If you have any more tricks you’ve learned over the years, it would be cool if you shared them here… the more we can share with each other the better!

    Cindy Lietz’s last blog post..Cool Polymer Clay Tutorial – A Fimo and Sculpey Cane Making Tip

  48. Andrea Dimmick, 11 August, 2008

    As i am new to polymer clay this is a very helpful tip,saves me having to waste baked pieces that have done a flip.

  49. Kimberlee, 11 August, 2008

    Finally, a baking surface I can count on to heat evenly! I can see how the even weight distribution, even heating, and also the even heating from above (as Kody pointed out) would help the pieces bake flatter and ultimately increase the level of professional appearance. But I was wondering why parchment? I am in the habit of using index cards (cheaper than my nice cardstock) and wax paper with my clay. Is there anything in particular about parchment which makes it a better choice than these?

    This tip has already helped me figure out how I’m going to improve my metal leaf pendants! (I’ve been obsessing over the back sometimes having a slight dip after I’ve sanded. They were totally smooth but not entirely flat always!)

  50. Cindy Lietz, 11 August, 2008

    @Andrea: That sounds so cute… are your beads really doing flips?! I’m glad this info will help. Don’t throw out your mistakes though… you can always cover them up with new clay and bake again. For more info on that read this article: What to do with Scrap Polymer Clay

    @Kimberlee: I like parchment because it is non-stick. It also is made for the oven so it takes the heat and it doesn’t transfer wax onto the clay like wax paper can. Plus you can get a huge roll of it at Costco for about $7 so it’s cheap. File cards will work well too so you can keep using those if you want to.

  51. Ashley, 18 February, 2010

    hi cindy :) first of all, i L-O-V-E your site! i am brand new to polymer clay and i am trying to learn as much as i can- and your site is THE most helpful one i’ve found! thanks!

    i also have a question- i am definiely going to try out the ceramic tile thing- but my question is: do you just put the tile directly into the oven? sorry it is a silly question- i have just never done anything like this before and i dont want to do it wrong! thanks! :)

  52. Phaedrakat, 18 February, 2010

    @Ashley: Welcome, Ashley! There are no silly questions — everyone has to start out somewhere. Asking questions is how you get better. Cindy has lots of articles on baking, conditioning clay, sanding and varnishing your pieces, etc. here at her website. All kinds of stuff for beginners as well as people who have worked with clay for some time. You can find the articles by using the “Topic Categories” or the search box at the top left-hand side of the page. Just click on a topic or type a keyword or two into the search box, and you’ll get a list of relevant articles. Here’s one about “Baking in a Tile Sandwich,” which gives a little bit more info about baking on tiles.

    Cindy also has a Polymer Clay Fundamentals/Beginners Video Package, which has something like 39 videos. It’s perfect for people just starting out in polymer clay, and is a fantastic deal.

    As for your tile question — the answer is Yes! However, I usually wash a new tile first (with dish soap or something like it.) I just want to make sure I remove any dust or warehouse ick that could end up in my clay. Then it’s safe to pop it in the oven. It’s a good idea to buy an extra tile to KEEP in your oven — it holds the heat, making your oven bake a bit more evenly and helping to prevent temperature spikes.

    Good luck with your new claying experiences, and Have Fun!

  53. Ashley, 19 February, 2010

    thanks so much for the clarification! :) i am really excited to peruse this website more and get started creating! :)

  54. Laurie P, 17 September, 2018

    Hi! I’ve been using the file folder (3 of them) method inside of 2 tins binder clipped together. Unfortunately once the piece starts to cool (and sometimes while in the oven), the file folders warp and therefore, put unwanted waves in my flat backed pieces. :( I would use the tile on top method, but my pieces are not flat on top, only on the back. Please help!

  55. Cindy Lietz, 18 September, 2018

    Hi Laurie, what I would do is add a few more layers of file folders, that should help. I would also make sure that the piece was lifted away from the paper just before putting in the oven and perhaps dusted with a little cornstarch so it sits a little looser on the paper and doesn’t pull up while it bakes. Hope that helps!

  56. Laurie P, 18 September, 2018

    Thank you so much! We will try that out and see how it goes. :)

  57. Alison G, 15 November, 2019

    hi cindy. my pieces keep snapping. almost all of them. i make them very thin because i like them to look and act almost like leather. (thinnest to second thinnest on the pasta machine) my question is, are they snapping because they are too thin? or are they not curing correctly? i use premo and fimo. thank you!

    p.s. please save me from tears. it’s so frustrating to work long and hard on a piece to have it break on you!

  58. Cindy Lietz, 21 November, 2019

    Hi Alison, they are not breaking because they are too thin. They are breaking because they have either not been baked hot enough (use and oven thermometer) or not baked long enough (I bake even thin pieces of premo and Fimo for one hour.) Properly baked pieces should be quite flexible and not break after baking… even if they are paper thin!

  59. Jennifer K, 18 July, 2022

    Hello, I keep getting pock marks/dents BEHIND my polymer clay earrings. I use a pasta machine to roll the clay and I knead by hand to condition. I cut my pieces and then see the dents appear on the back. I bake on a tile lined with paper. Everything is fine until I cut my pieces. The cutter doesn’t seem to matter. Thank you, Jennifer

  60. Cindy Lietz, 21 July, 2022

    Hi Jennifer, sorry for the slow response. It makes sense that you are getting a little distortion on the back of your cutout pieces. As the cutter is pushed through the clay (especially if the cutter is dirty or not that sharp) the clay pushes up the side of the cutter a bit and pulls from the back. This can be minimized by making sure your clay sheet is stuck down really well to a glass or shiny ceramic piece when being cut. Then use your clay blade to slide under the cut piece and transfer to your baking surface… either use a tile or pan lined with office paper or use my new favorite, directly on a pizza stone. The pizza stone is matte and holds the heat nicely so you don’t have to worry about hotspots scorching clay or shiny spots on the back of your pieces. To avoid getting divots on the back, make sure to gently press down your pieces, fully to the pizza stone. Another way to avoid uneven backs is to texture your backs with something rough like coarse sandpaper, woven fabric, sponges, stamps, air filters, texture plates etc. You can also bake, using the tile sandwich method. (Do a search on this blog to learn more about doing that.) Good luck and keep practicing. You’ll get nice backs before you no it! :)

  61. Jennifer K, 27 July, 2022


    Thank you so much for responding. I do use those methods but the issue seems to happen after I cut my pieces. It seems air is getting trapped with the cutter? Or maybe I’m not laying the clay down properly on the tile and air is getting trapped at that point.


  62. Cindy Lietz, 28 July, 2022

    Hmm, it sounds like you might not be pressing the pieces down smoothly to the paper that you’re placing them on. You can always use a piece of paper on the top to smooth them down, so that you’re not getting fingerprints on them. Also, if the pieces are flat on the top, you can also bake in a “tile sandwich“, which is tile/paper/polymer/paper/tile flipped over, so only the smooth side of tile is facing the clay. Good luck!

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