Conditioning How To – Polymer Clay Tools, Techniques and Instructions

Conditioning Polymer Clay By Hand

Several different ways to condition Fimo clay?

I don’t have a pasta machine. Is there another way to condition the clay? I didn’t realize the amount of work involved when I bought the clay. Can I use a roller instead of a pasta machine? ~Barbara

A: First let’s define what it means to condition clay. It’s basically just the process of thoroughly mixing or kneading the pigments and plasticizers together so that clay is consistent throughout and easier to manipulate. With conditioning, you also want to work out any air bubbles that may be trapped inside the clay. This can be done in a few different ways, with a few different tools.

You can condition by hand. Simply cut off small amounts of Fimo off the block and squeeze or knead the pieces in your hands until they are warm and pliable. Keep doing this in small batches. Then gather together the small batches into one larger ball and continue to knead until you can roll it out easily into a smooth flat sheet with an acrylic roller.

Warm hands will help soften the clay. Another way to warm the clay so it conditions easier, is to fill a hot water bottle with warm water and rest the clay on the bottle for a bit. Then knead.

If you find your hands getting fatigued from kneading the clay, you may want to use a ‘clay-dedicated’ food processor to do the heavy work for you. You can read about this technique here: Condition Fimo Clay with a Food Processor

By far the easiest way to condition polymer clay is with a pasta machine. I have written about how to use this helpful tool here: How To Polymer Clay Conditioning Tips

Those of you who have signed up to my Polymer Clay Tutor Guest List will have seen a video that shows you the proper way to condition clay to avoid trapping air. This is important because it is very frustrating to have a beautifully made bead or pendant come out of the oven with baked air pockets all over it! So you’ll want to make sure you are removing air from your clay and not adding it!

This Q+A article provided instructions for how to condition polymer clay by hand and with commonly used clay tools. If the information was helpful, please be sure to leave a comment below. Thanks.

Cindy Lietz SignaturePolymer Clay Tutor

  1. Barbara, 15 September, 2008

    Thanks for the extra ideas. I will let you know how my beads come out.

  2. Cindy Lietz, 15 September, 2008

    You’re welcome Barbara! That would be great!

  3. Louise T, 31 October, 2008

    You have supplied us with a wealth of knowledge and I am learning from each and every page I open in the blog as well as the videos. May God bless you.

  4. Laura, 01 April, 2009

    I have been given a HUGE box of polymer clay-probably 130 bars of Fimo classic and lots of sculptey in various sizes. It was from a woman who is going to a retirement home, whose daughter is the boss of my best friend.

    Anyway, I have no idea how old anything is, but the first try with some Fimo was very crumbly, only after half an hour of playing with it making it workable. Is there a specific method to conditioning old old Polymer clay?

    I also received in this ultra heavy box some bars of mixquick, which I am thinking of trying in the next day or so. How am I supposed to mix it in-knead it?

    Finally, with the big box came a few canes that this woman made, square and large, but very very highly detailed. Can you successfully reduce a cane that is who knows how old? It was just wrapped up in one layer of Saran wrap and put into a plastic bag.

    Thank you for your help, I really like your website; it is one of the only helpful online resources for artistic-typed polymer (no phony baloney stuff).


  5. Mary Beth, 01 April, 2009

    Aside from the food processor and pasta machine techniques, I have successfully used the Sculpey Mold-Maker clay to reconstitute old (extremely crumbly) clay. You can use this extraordinarily sticky clay to pick up crumbles easily.

    All the best!

  6. Cindy Lietz, 04 April, 2009

    @Laura: You lucky girl! I would love getting a gift like that, even if it was a little work to deal with! The one upside is you won’t need to leach out any plasticizers because it is too soft and sticky like the clay most of us are dealing with right now! ;-)

    I was thrilled to here you also got some Fimo Mix Quick which will be perfect for softening up that clay. I have a video in my Bead Making Course that shows you exactly how to use an old food processor for blending Mix Quick and old clay. Click the link by my name for more info on that.

    With this large a batch of old clay you will need ‘the big guns’ such as a processor and a pasta machine. Doing that much by hand, though possible, would be an enormous task, and you probably want to get to making beads. If you don’t have those machines yet, you can easily justify the cost with all the money you saved on clay.

    Once ready that clay will be perfect for making canes and beads because of its firmness. So rejoice! As far as reducing old canes, type the words ‘old canes’ into your search box at the top left hand side of this blog for tips on how to deal with those.

    @Mary Beth: Cool! I didn’t know you could use Sculpey Mold Maker to reconstitute old clay. Thank you so much for passing that tip along. I’ll have to give it a try!

  7. Cherie H, 20 September, 2014

    I have used sculpey mold maker to soften old clay. You need to add in very small amounts at a time. Works well!

  8. peggie, 30 October, 2009

    this question is not really about conditioning the clay, but i have been unable to find a topic to put this under. when i have done any kind of canework or any design………..and i want to roll it into my solid sheet under it, or roll it out into a different shape…………..when i use the acrylic roller, it invariably dulls the surface. i will be all excited about some popping happening thing, and when i roll it ………boom……..there goes the luster and the zing. i have tried cleaing the rod with alcohol or rubbing it with a soft towel………… you have any other suggestions?

    thanks, cindy!! how wonderful to have you out here helping the polymer clay expert wannabees~!

  9. Cindy Lietz, 30 October, 2009

    Don’t worry about that Peggie. The shine will come back when you sand and buff it.

  10. Irene, 23 February, 2010

    I recently purchased some Studio polymer clay, and when I opened the package, the clay was somewhat harder then the other pack. When I tried to condition it, it just turned into a crumbled mess. Everything I tried to do with it, conditioning by hand, adding liquid clay, didn’t help – it just stayed crumbled. Is there a possible way to fix it or I should just toss this one and get a new one? Thank you very much for your help.

  11. Phaedrakat, 28 February, 2010

    @Irene: I forgot to mention one thing, you never want to throw out your clay (even cooked, dirty, ugly, burnt!) As you learn more about polymer clay, you’ll find that there are uses for all kinds of clay. The hard or cooked stuff can be grated into other clays to give it a stone-like look. The crumbly stuff makes great Jupiter Beads.

    You can use slightly dirty or ugly clay as centers for beads, and then cover with your “pretty” clay. Lots of ways to use clay that isn’t perfect. Just wanted to let you know so you didn’t toss it. Have fun~

  12. Phaedrakat, 28 February, 2010

    @Irene: Hi Irene! Unless your clay has been partially cured (near a hot radiator, or maybe along the shipping route) you should be able to get it to a working consistency. Have you tried adding a drop or two of Sculpey Dilutent or Fimo Mix Quick? (or mineral oil, baby oil, etc.) Are you using a pasta machine? Have you checked out both of the articles Cindy links to in her article above? One of them is about Food Processors, which can be a huge help when dealing with hard, crumbly clay. There are lots of tips in both of those articles, as well as this one on Softening Clay Quickly.

    Here’s an article on Fimo Mix Quick

    Be sure to read the comments under the articles, as well, since there are lots of tips people use to get “difficult” clay to condition properly. If you haven’t already signed up for Cindy’s newsletter, you should. You’ll receive 3 Free Videos (one of them is about Conditioning Clay!) Click on the link in the article above (or there’s a “Yours Free” link on the top right side of the page.) This is a great deal not only for the videos, but also for the free color recipes (you get 8 a month!)

    There are articles with lots and lots of information on conditioning clay all over the website. You can use the search box at the top left side of the page to find articles on any topic. Type in a keyword or two, like “conditioning” “hard clay” “crumbly”, etc. and you’ll get a list of articles with loads of information on that subject. There are also tags at the ends of the articles you can click on. They’re right under Cindy’s signature (there’s one for conditioning, plasticisers, pasta machine, etc.)

    Also, did you read the comment above by Mary Beth? She mentions that Mold Maker (a product used to make molds of objects) also works for picking up the crumbly clay and softening it. I’ve heard about others using this — it seems to be working well. Just use a small amount at a time, though. Same goes for any of the softeners. Another tip I forgot to mention above is to mix the hard clay with a very soft clay. You can use the same color or mix a new one (or you can try translucent.) If you do not have a food processor, you can try chopping the clays together into little bits or use a cheese grater before mixing with your crumbly clay.

    I’m going to leave off here, for now (this is getting long!) I’m hoping that the articles and the videos will help you, or that trying Diluent or mineral oil will help you soften that crumbly clay & condition it. Leave a comment, though, if you need more help, and someone will be happy to give you more information. Actually, the best way to go is getting Cindy’s Fundamentals/Polymer Clay Basics Course. This is a 39-video course that covers everything about getting started with clay. Cindy demonstrates all the tricks and tips on how to condition, bake, and finish your clay pieces, as well as many other topics. Either way, let me know how it works out — I hope I was able to help! Good luck getting that clay tamed~

  13. Michele, 28 February, 2011

    I have tons of both Kato and Premo clay and can’t seem to get it pliable. The clay is about a year old. I am about ready to give the Kato to anyone who can use it. I have pounded it, chopped it up and put some glycerin on it to no avail. I just gave some to a neighbor (who usually works with Fimo) to see if she has better luck. I broke my Makins roller on the clay which was sad since the motor came in about a week later. Does anyone know if I can use a motor with an Atlas machine?
    At the time I also bought some Premo on line, after last years debacle I put the polymers away. I have started to macrame again and want to make some beads. So I decided to try to to break on the clays. This time the Premo, during church, I had about a 1/3 of a block in my hand, trying to warm and squeeze it but it wouldn’t get soft. So once at home I ran it through the machine for about 10 min. but it kept breaking rather than getting smooth and a bit elastic y?
    I really want to start making some things but have had no luck with any of the clays I purchased.
    While on vacation (college shopping) I took a class in Boston and had fun. It was cold there but I thought I would not have any problems living in a warmer climate (Hawaii) but I don’t ever remember having this many problems with any other medium I have worked with. (I also work with a polymer air dry clay and silver clay). Does anyone have any suggestions? Do you think it cooked in the mail? I am at wits end. Sorry to be such a whiner but everyone seems to be having so much fun with their clay and I can’t even condition it.

  14. Cindy Lietz, 28 February, 2011

    @Michele: Oh my goodness Michele that sounds frustrating! My guess is that you are on the right track in regards to the clay possibly being partially baked. Especially since you live in such a warm climate. It most likely got overheated just sitting on a plane or in the back of a truck on the hot tarmac. Don’t despair we can figure out a way for you to recondition this maddening stuff or at least be able to use it as inclusions in some faux stones or something.

    Before you give up on the hard clay, try typing in the words ‘hard clay’ or ‘softening clay’ or ‘conditioning clay’ into the search box at the top of the page. This will lead you to several helpful articles on how to soften hard clay.

    As far as using glycerin to soften clay, I have never used that myself, so I can’t tell you whether that will work well enough for you or not. I can tell you that drops of baby oil or small amounts of Fimo Mix Quick or Sculpey Mold Maker work really well for softening clay. Though if your clay is truly partially cured, then these things won’t really do much for you.

    Another option is to try and get some new clay. I do know of a polymer clay artist named Moe, who lives in Hawaii, who may be able to tell you where the best place is to get clay. She has worked with polymer clay for years and certainly has been able to source some decent clay there somewhere, since her work is lovely. Try going to her blog at and ask if she could help. Let her know I sent you.

    If you are not able to recondition the clay to your liking, like I said, you can always use it for making into faux pebbles and stones. You will need some fresh clay to mix it into but it will bond with the hard clay quite nicely. If you want to know what I am talking about, click the link by my name and it will take you to preview clip of the tutorial video.

    Don’t worry… we will get to the bottom of this. You will be making beautiful beads for your macrame projects before you know it… and these frustrating days will become a thing of the past! Do let us know what happens and if you need any more help, don’t hesitate to ask!

  15. Cherie, 28 February, 2011

    Sculpey Mold maker is great for softening hard or crumb ly clay. Use very tiny amounts. I had a bit of clay mixed with a bigger quantity of mold maker. I just wanted to see if I used more and rolled it out thin and baked if it would be more flexible; it burned.

  16. Michele, 01 March, 2011

    Thank you Cindy and Cherie for your comments and support. I really appreciate it. Cindy I will try to contact Moe, I briefly went to her blog site. Cindy, is there anyway I can send a pkg. to you for you to see if the clay is partially baked? I did manage to some what condition 1/3 of a pkg of pearl Premo, with quite a bit of baby oil. It isn’t crumbling but doesn’t feel like the clay I played and had fun with in Boston. It still feels stiff. Stiff is better than sticky right? This is the most successful I have been. :) I am thinking of running the crumbs through a food processor again while drizzling baby oil. I just think that it shouldn’t be this hard to have some success and fun. Oh does anyone know the best way to clean the clay from the food processing bowl?

  17. Cindy Lietz, 01 March, 2011

    @Michele: You’re right, it shouldn’t be this hard. I’m glad to hear you are having a little success though. If you want you can send me some of the clay for me to check out for you. There is a mailing address you can send stuff to if you click the “About Cindy Lietz” link at the bottom of this page and then scroll down to the bottom of the page you land on. When I receive the package and have a look at it, I will respond with a comment in this thread. So be sure to keep an eye out for it. Hopefully we can get to the bottom of this and get you claying!

  18. Michele, 01 March, 2011

    Cindy, I have a few more experiments but may still send you some clay to check out, thanks for that. I added some chopped Premo to a mini food processor and added baby oil to it. I think the heat and the oil together worked to form a ball that I later was able to roll out. I think it still needs conditioning but this is the best result I have ever achieved so far. Also, it seems that the baby oil cleaned out the bowl a lot better than alcohol did. I had some orange clay that I could not remove with alcohol alone. With the baby oil, it cleaned it like new. I did try to condition some Kato clay.
    One batch that was chopped & had been bagged for about a year with some glycerin (I believe I read this in one of Donna’s book) and I added some polyclay – what a sticky mess. I tried adding more clay, it seemed to stick together but it was very difficult to remove from the bottom of the bowl. I had to dig it out. Tried a package of translucent clay which is suppose to be softer? with a bit of baby oil, it was better but the clay did not ball up like a piece of dough the way the Premo did. I put all the Kato clay in a big baggie and took it outside and gave it a few whacks on the ground. It seems as if it is at least sticking together but will need a lot more conditioning. It is a bit difficult to explain, it is still sticky if I put it on my board but at least the pieces are start of staying together? I don’t know if this is good or bad. I am wondering if I should just dump the ones with glycerin even if there must be about 8-10 packages worth of clay. And clay is expensive here with a very limited selection. (Fimo and sculptey I think at $2.99 a package). We have no Michaels etc. I usually find it cheaper to order quantities on line with late rate shipping boxes. I am forgetting what a good piece on conditioned clay feels like. Plus is it true that all of them feel different depending on the brand and type? Thanks for putting up with me and for all of your help. I am just a frustrated person right now.

  19. Sue F, 02 March, 2011

    @Michele: Hi Michele! I hope some of the following helps!


    I’m one of the Kato enthusiasts around here — and Kato should not be sticky! — but unfortunately I don’t have any glycerin to test how it behaves.

    I’d heard of using glycerin as a release agent with polymer clay, but not as a softener, so I did a bit of internet searching. It definitely seems to be recommended or used by some people for softening polymer clay, but I also saw enough questions about it and its effects that I wouldn’t use it myself until I could do some controlled testing to check whether it really did work satisfactorily with Kato or not. From other tests I’ve done (e.g. reactivity with other plastics in the uncured state, results of curing in cornstarch, etc.) I think there is enough difference in composition between the various clay brands that even if it works with one brand, it might not work with another.

    Donna Kato worked with other clays before she developed her own brand, so unless she mentions a brand or you know the date of her comment it might not actually be referring to Kato clay. I only have two of Donna’s books, but neither of them mention glycerin as a softening agent although they do mention other things like Kato Clear Medium, Mix Quick, and Sculpey Clay Softener (not specifically for softening Kato Polyclay, however).

    I hate to say it, but you might have to throw away the Kato that had glycerin added. And this is from someone who thinks $2.99 a package sounds really cheap! (Here in Australia you’re looking at prices in the $4.50 to $6.00 range per 2oz pack depending on brand.) Don’t do it just yet — I’ll see if I can find some glycerin and test it with Kato on the weekend — but be prepared for the possibility.

    Known Kato-Safe Softening Agents

    While I rarely want to soften Kato, the two softening agents I’ve used are:

    1. Kato Clear Medium (Kato’s brand of liquid polymer clay), which is what I always use now.

    2. Vaseline petroleum jelly, which is probably more accessible but doesn’t do as good a job (it weakens the clay somewhat, and some of the beads I’ve made with Kato softened this way cracked).

    Clay Softening Techniques

    There are two techniques I use, depending on whether I can condition the clay or not. I know you can’t, so I’ll start with the “not” technique.

    1. When you can’t condition the clay at all, cut it into small pieces and put it into a heavy-duty sealable plastic bag. Add either a good squirt of Kato Clear Medium, or a small amount of petroleum jelly, then seal the bag and manipulate it and its contents so that the clay pieces are thoroughly coated with the softening agent. Leave it for at least a day, then squish, squash and further manipulate the lot through the bag until everything is incorporated. There will be quite a mess initially, hence the use of the bag, but it should all come together into a nice lump of softened clay. I’ve only ever had to do this once, and it was when I was a newbie and was trying to condition Kato the way I’d read for conditioning other brands. I probably wouldn’t need to use this technique any more, but it’s useful to have up your sleeve.

    2. When you can condition the clay and roll it into sheets, but you want it to be softer anyway, roll it out into quite thin sheets then spread an extremely thin layer of your softening agent over the surface. Let it sit for a while — at least 10 minutes; longer is better but I usually don’t have the patience! — then fold it so that the softening agent is on the inside, and feed it through the pasta machine a bunch of times until it is fully incorporated. Repeat if necessary. You don’t need to wait as long after applying the softening agent as you do with the first technique as there shouldn’t be enough softening agent on the clay surface to make much if any mess.

    Conditioning Kato

    Also, Kato is quite easy to condition *IF* you know the trick, but it can be incredibly frustrating to condition if you try to do it the same way you would with a softer brand like Premo or Fimo Soft.

    There are two main conditioning techniques that are great for Kato:

    1. Cut the clay into 3mm(ish) slices, then roll gently with an acrylic rod in all directions to start the process (sort-of optional, but hey, I might as well describe it the “proper” way!). Feed a slice through the pasta machine on the thickest setting but don’t fold it yet! Set the pasta machine to one or two settings thinner, then roll the clay slice through it on this new setting, again without folding. Set the pasta machine a further time to one or two settings thinner, then roll the clay slice through it on this third setting. Depending on the settings on your pasta machine, whether you went one or two settings thinner each time, and how crumbly your clay was to start with, you might want to do one further cycle of setting the pasta machine to a thinner setting and rolling the clay through. You want to end up about at the middle setting or slightly thinner by the end of this stage. If the clay slice breaks or starts to crumble, hold it together as best you can but don’t fold it, and definitely don’t squash it up into a ball! Once you’ve got to the middle-or-a-bit-thinner pasta machine setting, stay on this setting and continue conditioning as for other brands by folding the clay once, feeding it through, folding it once, feeding it through, etc. The clay will condition much more quickly on this thinnish setting, although you can back off to a slightly thicker setting after a few passes if you prefer, once the clay starts holding together properly. While this took quite a bit to describe, in practice it hardly takes any more time than properly conditioning softer brands at just one pasta machine setting.

    Donna Kato has a free CraftEdu tutorial on this process. See:

    2. The “Jana Whack” method, named for polymer clay artist Jana Roberts Benzon. This is good if you need to work your frustration out on something! Many people swear by it, but I personally find it less effective and not as fast as the preceding method (although it is fun :D). Basically, take your wrapped package of firm clay and a mallet to a hard surface (e.g. the floor of your garage). Put the clay package on the hard surface with either the top, bottom or side of the package facing up (not the front or the back up at this stage), whack it several times with the mallet, then turn the clay package so that the top, bottom or another side is up, whack it again several times, turn the clay package again, whack some more, and so on. You want to whack it pretty thoroughly — I’ve seen it suggested to reform the packaged clay into a cube through this process; the wrapping will protect it well — using several cycles of whacking if necessary. You can whack the front or back once your clay lump is less flat, but keep in mind that you want to be able to slice it easily later. Once the clay seems softer and is holding together, slice it and condition it as normal by rolling it multiple times through the pasta machine.

    The above are my descriptions of the two techniques. They’re also described in this document:

    Differences in “Feel”

    I do think that the various clay brands all feel different when conditioned, but that doesn’t make it harder to tell whether a particular brand is conditioned or not. Luckily, that’s still pretty obvious regardless of brand.

    For the brands I have on hand:

    * Conditioned Kato feels quite firm but extremely smooth and pliable. It is not sticky at all. The newest softer Kato formulation is about the same firmness as the oldest stiffest Premo, but it never gets sticky like Premo does.

    * Conditioned Premo, depending on whether it’s the older firmer formulation or the newer softer stuff, feels somewhere between medium-firm and very soft. It always feels a bit sticky to me, even the old firm formulation.

    * Conditioned Sculpey III varies a lot, from almost like silly putty to medium-soft. It’s somewhat sticky, and has a bit of a powdery feel to it in my opinion.

    * Conditioned Fimo Classic feels roughly as firm as Kato. It isn’t sticky either, but it feels a bit powdery to me, i.e. not as smooth.

    * Conditioned Fimo Soft feels quite soft but with a slightly powdery consistency.

    If you’re not sure if your clay is fully conditioned, keep going. You generally can’t overcondition polymer clay, although some brands might become a bit stickier or softer with extra working.

    One test is to bend a sheet of clay over on itself: if the clay cracks or fractures at the bend, it isn’t conditioned enough. Just be aware that soft brands still need some conditioning even if they are soft enough that they don’t crack even straight out of the package.

  20. Cindy Lietz, 02 March, 2011

    @Sue F: Just so you know Sue… I think you’re awesome! Thank you for sharing your incredible in-depth knowledge!

  21. Sue F, 03 March, 2011

    @Cindy Lietz from Kato Polyclay Recipes by Sue F: Oh, I’m blushing now! LOL

    I just thought I’d contribute on the bits I know something about. :)

  22. Michele, 02 March, 2011

    Sue F., you are an amazing person!!! Thank you so much for sharing all of your knowledge and insights. WOW! I will give the Kato clay another try using your suggestions but if it does not work out with me or my neighbor, I would be willing to send you a flat rate envelope or small box of clay for free. I checked the prices out for the shipping and it is not too bad.($14) It would make me really happy to give the stuff away to someone who loves the stuff and is willing to share what they know. Which is obviously you. Let me know what you think, my email is ________ ** removed for privacy reasons. If you google me it will come out wrong and say I am a florist which is not true, (I don’t know how they got that info), I make flowers to sell but am not a florist. I’ll keep you informed about the progress with the Kato clay or if you know someone who is coming to Hawaii for vacation? Thanks again.

    >> **
    This email was removed for privacy reasons. Email addresses don’t show up in any of the posts or comments at this site. It is for everyone’s protection and to keep the Spambots away. Spambots are little automated programs that scurry around the Internet “harvesting” stuff they shouldn’t be. Whenever you post your email address online, or anyone else’s s for that matter, that contact information is guaranteed to be added to many different spam lists that will fill up your inbox with all kinds of crap messages that no one wants to see. Everyone can actually do their part to help combat spam by simply not posting email addresses anywhere on the Internet, ever. Some people try to be clever by spelling out the word “at” instead of using the universal email @ symbol…. but unfortunately those nasty little bots are a lot smarter than that. ~Cindy

  23. Sue F, 03 March, 2011

    @Michele: That’s really sweet of you, Michele! If it comes to that I’d certainly pay postage and packaging and what not, but we still might be able to salvage your clay.

    And as Cindy said, even if it is partially cured, you can still use it along with some good clay to make faux pebbles, stones and gemstones. That’s always fun!

    Or you could probably chop lumps of it and use those for bead cores, with a thickish layer of good/fresh polymer clay around the outside for strength and to enable shaping.

    I’ve also seen some nice large-faceted polymer clay beads that were apparently made by taking a belt sander to the cured clay (or vice versa? see So you might even be able to cut your partially-cured clay into bead-sized roughly faceted nuggets, cure them, and then finish shaping/faceting them that way (or by hand sanding). It’s pretty easy to drill holes in them after curing (I’m doing that more and more). They definitely won’t be as strong as if you used conditioned clay, but it might be worth trying anyway as they might still be “strong enough”.

  24. Sue F, 03 March, 2011

    I was really curious about the glycerin, so I got some this evening and tested it with Kato, Premo, and Fimo Classic (i.e. the two brands Michele mentioned plus another firm clay). What it does is very brand-specific.

    Glycerin and Kato

    Summary: No good as a clay softener. Doesn’t mix into the clay properly and therefore causes bubbles in the cured product, although the strength seems unaffected.

    The glycerin beaded on the Kato when I applied it, which I didn’t think was a good sign, but I persisted. However, it was almost impossible to get the glycerin incorporated into the Kato. When I tried to do this by pasta machine (folding a coated sheet, running it through, folding it again, running it through, etc.) all that happened was that after a couple of passes all the glycerin had escaped from the clay and was coating the rollers to the extent that there was no traction at all: even when I shoved the clay downwards into the opening between the rollers while turning the handle it wasn’t drawn through, and the rollers just spun uselessly (I did say I’d heard of glycerin being used as a release agent, and this behaviour means it’d probably be a pretty good one with Kato!). So I tried to knead some in by hand, but that was pretty messy. In the end I seemed to get a bit incorporated — the clay was slightly stickier, anyway, even after washing my hands and then cleaning them further with isopropyl alcohol — but it didn’t soften the clay much if at all.

    I cured a control sample, plus a test piece made from the Kato that had as much glycerin in it as I could get (not much), at 150C for 40 minutes (i.e. how I’d normally cure Kato pieces of that size).

    The test piece with glycerin looked quite odd after curing. It had lots of little raised areas all over the surface, and looked like it had a huge amount of plaquing all the way through it. I think both were due to the glycerin not mixing in properly after all, so that it separated out and bubbled during the curing.

    While the clay was still warm the piece with glycerin was much more flexible than the control sample, and it was still slightly more flexible than the control at room temperature. Somewhat to my surprise, the glycerin test piece was as strong as the control sample when tested by bending sharply back and forth and counting how many beads would crack and then break the clay.

    Glycerin and Premo

    Summary: Ineffective as a clay softener, and it weakens the clay too.

    The glyerin beaded again with Premo, although not quite as much as it did on the Kato. However, it could be incorporated into the Premo by folding and rolling multiple times through the pasta machine although some escaped and smeared the rollers before eventually being worked in. It didn’t soften the Premo all that much, even after I’d repeated the process of adding glycerin to it three more times. It did make the Premo stickier though!

    I cured a control sample, plus a test piece made from the Premo that went through four rounds of glycerin addition, at 130C for 60 minutes (i.e. how I’d normally cure Premo pieces of that size).

    The test piece with glycerin looked normal after curing, but it was definitely more brittle than the control sample and snapped as soon as I bent it past 90 degrees.

    Glycerin and Fimo Classic

    Summary: Very effective as a clay softener, with little if any effect on clay strength.

    The glycerin still beaded on the Fimo Classic, but the least amount of all the three clays tested. It was relatively easy to incorporate although there was still a bit of a messy stage with smeared rollers before everything came together. The degree to which the Fimo Classic was softened was quite significant. In fact, after incorporating the first small amount of glycerin I thought I’d try adding a little bit more to see what happened, and ended up with soft sticky goop that wasn’t good for anything.

    I cured a control sample plus two test pieces: one was the accidentally over-softened goop I mentioned, glopped onto a tile for baking purposes and sort-of squidged out to be about the same thickness as the control sample, and the other was Fimo Classic softened to about the consistency of soft Premo, then rolled to the same thickness as the control sample. The samples were cured at 130C for 35 minutes.

    The test pieces with glycerin looked normal after curing, and they didn’t seem any weaker than the control piece although I was a bit disappointed in the strength of them both (probably at least partly my fault; I don’t use Fimo enough to have developed a “maximum strength” baking regimen for it).


    Glycerin softens Fimo Classic very effectively so add it sparingly; in brief testing there wasn’t any noticeable weakening of the clay.

    Don’t use glycerin to soften Premo or Kato: it doesn’t really soften either of them, it weakens Premo, and it doesn’t mix properly into Kato so the cured clay is lumpy and bubbly.

    The Kato samples were noticeably stronger than the Fimo Classic (next strongest) and the Premo (weakest out of these three, although this is relative as Premo is a reasonably strong clay).

    That Kato That Already Has Glycerin…

    Glycerin is water soluble, so you might be able to wash it off (make sure the clay dries really thoroughly afterwards, particularly if it’s in small pieces). You could then try some other softening agent… or try doing something with it that doesn’t require softening. :D

  25. Michele, 03 March, 2011

    @Sue F:
    Sue you are an amazing person! You did all those tests? Thank you so so much for all of your time and work and for sharing in such a concise and understandable manner. I didn’t realize about all those spambots and that you did not get my email address. Maybe Cindy can help? cause I did pack a small box for you already and no money is wanted. Appreciate you a lot. I am going to try to wash that nasty glycerin off the clay. I am starting to get excited again about polymer clay! Oh do you know about painting clay? before or after and the differences? I want to make these flowers- free hand and the inside color is different than the outside color. I will also check the blogs but you are such a wealth of information!

  26. Cindy Lietz, 03 March, 2011

    And there you have it… the definitive guide to using (or not using) glycerin with polymer clay. I think we should all chip in and buy Sue a white lab coat for all the scientific testing she does around here :-) Thanks so much for taking the time to document and share your results. What a great post!!!

  27. Sue F, 04 March, 2011

    @Cindy Lietz from Rose Petal Beads:

    I think we should all chip in and buy Sue a white lab coat

    You think I don’t already have one? LOL

  28. Michele, 04 March, 2011

    Hello Cindy and Sue, I wanted to thank you both cause I think I may have finally conditioned some Kato Clay. I had to use more than one method. I could not put the clay through the machine as you suggested Sue so I chopped it up, put on some kato poly clay?, then whacked the package till it started to stick together. Then I worked it a bit smoother till I could pass it through the machine in the way Sue suggested and viola! I think I have clay that is almost conditioned. It is something I never thought I would see. Nicely rolled clay! I worked for over 3 hours last eve and did two batches, one fresh clay and one with the glycerin (un rinsed). I hope the glycerin one does not bubble when I try to bake it but will let you know. I want to try the Premo tonight and see which clay I prefer to use. I don’t know how you ladies do it cause I was exhausted and had a sore arm. :) Do some people use more than one clay depending on what they are making? Also, thanks again Cindy for what you did and all that you do. I will follow your suggestion soon.

  29. Sue F, 04 March, 2011

    @Michele: You’re most welcome, Michele!

    I actually find tests of that kind quite interesting to do because they help me understand the properties of the different clays better. (So when I have a hare-brained idea I want to try out, I’m less likely to get myself into trouble! LOL)

    It’s great to hear that you’re getting excited about polymer clay again! Did you have any luck washing that glycerin off? (Even if you didn’t, there are some faux gemstone techniques where the super-plaquing would work out quite well; you’d probably just need to sand the surface a lot more than normal to smooth that out.)

    I don’t know much about painting polymer clay because I generally like using the clay itself for the decorative aspects, but I have used paint both before and after curing the clay. Off the top of my head (knowing I’m forgetting some things!):

    Before curing: I’ve done a deep-crack, large-flake crackle technique which involved painting many layers of metallic acrylic paint onto a thick sheet of unbaked clay which I then manipulated and rolled to give the crackle effect. I’ve used Helen Breil’s techniques with textured clay and Lumiere paints for some really lovely colour transitions and dimensional effects. I’ve used oil paints marbled into uncured translucent clay when making faux stones and gemstones. I’ve made faux turquoise and similar faux gemstones by coating chopped-up clay with acrylic paint, letting it dry, then collecting it all together to shape before curing.

    After curing: I’ve used both acrylic paint and oil paint for highlighting/lowlighting textured clay surfaces after they’ve been cured, e.g. brush on and rub mostly off before it’s dried, or brush on, leave to dry, then sand so that only the paint in the etched areas remains.

    For your flowers with a different inside colour, you could “paint” the insides of the petals after shaping but before curing with suitably-coloured mica powders (PearlEx, Perfect Pearls, etc.), using a fine, soft paintbrush. You don’t need to stick with a single colour, for instance you could use a deeper colour in the throat of the flower, or blend from one colour to another from petal edge to centre, or whatever you like. Mica powders could be one way to achieve the slightly luminescent appearance that real petals have, and if they’re inside the flowers they should be protected enough not to need a coat of anything on top as a sealant.

    Another idea, but not involving painting, would be to make separate sheets of clay for the outside and inside colours, put them together and roll to the desired thickness, cut your petals out from that, and then do final shaping, edge tapering, etc., by hand. Subtle skinner (or teardrop) blends would probably work well, particularly if the clay colours included some mica clay (e.g. Pearl) for the luminescent effect, and maybe some extra translucent clay to minimise any visual flatness. (You should be able to do the same kind of thing even if you use a cane to make a patterned petal interior: take a thin slice of the cane, back it with a thin sheet of whatever clay you want for the outside of the petal, then shape as required.)

    I also know that Cindy has published at least one tutorial on making flowers from polymer clay. I have to admit I didn’t pay much attention to that particular one myself because it’s totally not my kind of thing, but have a look at the preview and see if it’s on the right track for what you want: Variegated Sculpted Rose Beads

    Have fun! :)

  30. Michele, 04 March, 2011

    Loved the rose video preview and will be joining soon. I love the idea of using a cane to make at least one flower. My flowers are all usually made free form, one petal at a time. This seems so much easier. Thanks Sue for letting me know about the video and Cindy thanks for making the video, this is right up my alley. :)

  31. Silverleaf, 06 March, 2011

    @Michele: I think you’ll like that video, it’s really cool! I’m not really into sculptural flowers but I worked through it anyway and it was good fun, and I made some pretty roses by the end of it.

    As for painting, I just want to add a couple of ideas.

    Apparently some paints work well with clay, and others don’t. Acrylic paints are generally fine but oil paints can react with the clay and ruin it, so whatever you choose to use I’d recommend baking some sample chips and painting them and leaving them somewhere for at least a couple of months to see if the paint’s clay-compatible. Better to wait a while before you paint your flowers than to spend hours shaping and painting them only for them to get all sticky and soft later on! Anyone else have brands they can recommend that definitely work?

    I like Sue’s mica powder idea. Also, Perfect Pearls have a special resin mixed in which bonds with the clay when it’s baked so it doesn’t rub off as easily as Pearl-ex. And you can mix the powders with water and paint it onto baked clay (then rebake to set the resin). Maybe add a thin layer of Future to protect the mica if it’s in a place that can get rubbed easily.

    Maybe alcohol inks would be fun too, they are translucent and you can “thin” them down with something like rubbing alcohol (I’ve actually used a small amount of high-proof vodka for this too) and paint them on baked or unbaked clay. Pinata or Ranger inks are good (I like the Tim Holtz Adirondack inks).

  32. Sue F, 04 March, 2011

    @Michele: I’ve just seen your latest post, Michele — posted while I was typing my last long one, I think! — and it’s fantastic to hear that you’ve had some success with conditioning your Kato clay! Hopefully your Premo will also behave.

    You’ll probably find that you have one generally-favoured clay, but that other clays are handy to have around for different techniques.

    I like Kato best by far because really firm clay suits how I like to work most of the time, but I also have quite a stack of Premo because it’s much more manageable for things like extruding. I really like a Ronna Sarvas Weltman-style bead where a solid core is completely covered with very fine parallel extruded clay strings, and I always use Premo for that (I’ve broken a couple of extruders by forcing Kato through them). And for an example of a technique that requires a firm clay, I recently did Christine Dumont’s online Butterfly Beads course (awesome fun!); that technique is quite sculptural and it would be close to impossible to achieve satisfactory results with a soft clay.

    And as for how *I* do it… well, luckily I’m pretty strong! LOL

  33. Michele, 07 March, 2011

    Hi Silverleaf, thank you so much for all your ideas. I am planning to try the Ranger alcohol inks. I like your vodka idea too. Who know maybe a little nip will calm me down. LOL :0

  34. Cindy Lietz, 07 March, 2011

    Awesome sharing of ideas guys!! Thank you so much Sue and Silverleaf, for coming to Michele’s rescue!

    I just thought I’d pop in here too, and mention that there is a video on Distressed Paint Finishes on Polymer Clay. The link by my name will provide more info about that tute, as well as about some paint brands I’ve used successfully with polymer clay.

  35. Jocelyn C, 13 October, 2012

    LOL, a classic bump…so informative.

    Cindy, I cannot wait to see what you think when you put Kato through it’s paces. So glad you got some. Hint…..

  36. Connie F, 11 January, 2013

    I am having a lot of problems with Premo clay being dry, hard and crumbly right out of the package. The clay was brought in the last three months. So it should not be old!

  37. Cindy Lietz, 15 January, 2013

    It sounds like the clay may be partially cured Connie. If it was shipped during the summer, it may have been ‘cooked’ in the cargo hold of the plane or in the back of the truck it rolled in on. If you actually got a fresh block, it would be soft. Especially now with the new (last couple of years) formula. See if they will replace the packs for you, from where ever you got them. If it is too much of a hassle, just add the crumbly clay to fresh clay and make some faux stones. Just don’t throw it out. It is still worth keeping!

  38. Lena S, 20 September, 2014

    So, I ran across this product this morning when I couldn’t fall back asleep. Has anyone used such a thing? Any opinions? It’s called a Never Knead.

  39. Lena S, 20 September, 2014

    It also made me wonder if one could make something with a flexible silicone dish and a vice. My brain is turning now. I am intrigued.

  40. Cindy Lietz, 20 September, 2014

    Hi Lena… I’ll be doing a demo video on the NeverKnead machine fairly soon… so stay tuned for that :-)

  41. Lena S, 21 September, 2014


    I was texting my dad about it and asking him if there was something the “tool world” that might do something similar. He said he’d think about it. Later that day he told me that he and his wife decided to gift one to me! WOOOO!! Super excited. He called to order and got Debra (the owner/inventor) and said she was super nice. I should get it next week. I am super excited.

    I read a little bit online and people have also used it to “wake up” old canes. I’m a newbie, so I don’t completely understand how that would work – but it sounds good. (:

  42. Lena S, 02 October, 2014

    My NeverKnead showed up today. I had to take a work break to go try it out. There is practically nothing to set up out of the box (you just put the handle in and tighten it). I agree that it might be nice to bolt it down – but I didn’t have any problems as long as I was mindful of the pressure I applied.

    Let me tell you – kneading an entire block of clay out of the package is a thing of beauty!

    When I first started playing with polymer clay I stored some in some “bad” plastic and it just leached all the good stuff out of it and ruined my plastic. I was so upset because I ruined several blocks of clay. This stuff was really brittle. But, I mixed some PC crumbles and Bake N Bond and put it in the NeverKnead and got it back to usable. It did take a little time – but since it wasn’t much physical effort it was worth it.

    Oh, AND another perk I discovered was that it was super easy to reshape my clay block into a shape that would fit my tiny plastic drawers for storage! A new block doesn’t quite fit. BONUS!

    I’m sure I’ll learn much more when Cindy does her tutorial – but I really like it!

  43. Jocelyn C, 05 October, 2014

    Wow, Lena thanks for the share. Amazing machine. Cannot wait for Cindy to show it to us. Always been my suspicion that unproperly conditioned clay, no matter how soft it is out of the package, is one of the main reasons for cracking and breakage.

  44. Lena S, 05 October, 2014

    That would be a great experiment for one of the testing videos. It makes sense that it would make a difference. I always wonder how conditioned clay is right out of the factory. Do they bother conditioning it, or maybe they do it just enough to package. How long would it last, etc. I don’t understand the process of making it so it does leave some questions. But, I bet you are right about the cracking!

  45. Cindy Lietz, 06 October, 2014

    Thanks guys for the comments! That would make a good test lab! I am looking forward to using this machine and doing a review on it. Stay tuned…

  46. Tracy Parsons, 07 March, 2017

    Hello,firstly I have to say alot of your basic clay tutorials have really helped me. I came across polymer clay about 14 months ago,and about 12 months I started just making pieces here and there,I’ve got a little better and hope to sell pieces eventually,my biggest struggle is clay getting too conditioned it just sticks too the surface and my fingers and then the shape I’ve spent ages to get has been ruined,I’ve ever been using the tiniest bit of corn flour(I’ve emailed in the uk so I think you guys call it corn starch?) And it really helps,however when I come to glaze my items it leaves a milky residue which is so upsetting when I’ve spent so much time(usually late into the evenings after work) and it’s unsaveable.Do you have any advice or tips on any of the above,I’d appreciate it very much.
    Tracy from Stevenage in United Kingdom

  47. Cindy Lietz, 08 March, 2017

    Hi Tracy, I don’t believe any piece is un-saveable, especially if it is just to do with the finish. You can always remove the top surface of your piece with rubbing alcohol or acetone, so most things are saveable.

    The first thing you should do is do a search on this blog for leaching your clay. Sounds like it is too soft and sticky in the first place and needs some oils leached out of it.

    Secondly, if you do have a lot of cornstarch that has been ’embedded’ into the surface of your piece, it could be the reason your pieces are looking frosted after baking. I would suggest rinsing the cornstarch off of your pieces before you bake them then. That should help.

    Also consider popping your clay into the fridge or setting on n ice block to cool it down and keep it more firm. It could be an issue with the brand of clay you’re using as well, so perhaps switching brands would help you too?

    Anyway, there is lots of cool info on this blog that should help you, if this wasn’t enough. Good luck!

  48. Celeste Day, 13 April, 2017

    My light switch covers keep breaking I have conditioned , cooking with an oven thermometer, cured them for an hour what are these little cracks from . The thickness is the first setting on the pasta machine.

  49. Cindy Lietz, 14 April, 2017

    What brand are you using Celeste?

  50. celeste day, 17 April, 2017

    premo, thank you

  51. Cindy Lietz, 17 April, 2017

    Are you tightening the screws down too hard? Maybe you need to leave the original baker plate on with your clay cover on top of that for more support?

  52. Celeste day, 19 April, 2017

    Actually they are cracking before I put the screws in! What should the thickness be? I have heard from one eighth to one quarter. Thanks again

  53. Cindy Lietz, 20 April, 2017

    Hmm, it sounds like it isn’t curing well enough. The clay should be much stronger than that, even if it is super thin. I would try this… since those pieces are cracked and wrecked already, you can do a little test lab testing of your own. Try bumping the temp up a little. Those plastic particles need to ‘melt’ together to really bond well. Maybe your oven temp is going up and down too much and not having a chance to cure properly at the right temp? Maybe try baking even longer too? If that doesn’t work, just keep the back plate on and there shouldn’t be an issue with cracking at all. Good luck!

  54. Strider G, 25 September, 2018

    I have inherited a bunch of Premo, Eberhard Faber, Sculpey, and other brands of modeling clay. I don’t know much about this stuff at all as I haven’t ever gotten into this kind of thing. I probably have 100+ little blocks. It seems hard and I don’t know if it is still good or if I should throw it out. I saw some of the videos on YouTube and you guys seem to be way more knowledgeable about this than all the rest. I hope to hear from you soon. Thanks!

  55. Cindy Lietz, 25 September, 2018

    Hi Strider, thank you for the compliments! You should never have to throw out your polymer clay… even if it is old and dried out… a brand you can’t identify… soft and squishy… whatever the condition. As long as it is actually an oven bake polymer clay and not a modeling clay like plasticine or an airdry polymer clay, it never “goes bad” and you can use it in some way.

    I have several videos on how to soften clay that is too hard. (Just use the search box at the top of the page to find those.) I also have videos on how to firm up clay that is way too soft.

    You can even still use old clay that just won’t soften up because it has been stored poorly and is partially cured… just chop it up finely and add as an inclusion into some translucent clay to make faux stones.

    With clay you can’t identify, or don’t know what temperature to bake it at, just mix a small percentage like 10%-20% of the mystery clay into a good quality clay like Premo, Souffle, Fimo, Kato Polyclay, Cernit or Pardo, and bake it at the temp of the good clay, and you’ll be able to use it up. In addition you can use the unknown clay to mix with liquid clay to tint it or make into a paste that you can use for faux icing, grout on polymer clay mosaics, filler for cracks, polymer clay ‘paint’ and all kinds of other cool things.

    Basically, you should ever have to throw polymer clay out! :)

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