Cornstarch and Polymer Clay Beads | Things That Belong Together

I use talc or spritz of water for mold release and haven't made anything so delicate as to need supporting yet, and I use the bleach idea for keeping the clay colors bright. I don't cook on the level to have cornstarch in the kitchen.

Believe it or not, I find that every bead or item I bake in cornstarch is actually really weak when it comes out of the oven. I use Kato Polyclay, and I'm not sure if this makes any difference. But my colors are the same in or out of cornstarch and I find that my beads bake muuuch harder when out of cornstarch.

Random, I know, but I currently dont' like cornstarch cause of the damage it has done to my precious items.
.

@Ken: You are cute! You could just buy a box of cornstarch for your studio with no intention of ever cooking with it. :-) A box costs about a dollar. It may be safer than using talc. I hear talc is very bad if it gets breathed in. Just an idea. It is very handy for the fingerprints, even if you don't use it for anything else.

@Karrah: Since I am still waiting for my Kato clay to arrive and I have not worked with it yet. I can't be positive weather or not it is an issue with the brand or not. The only time I have ever seen a loss of strength is when I've let the raw bead sit in the cornstarch for a day or two before baking. Are you baking your beads for a full hour, or just the half hour that most people do? It may be that the heat had not penetrated to your beads and therefore were not properly cured. Baking for an hour will compensate for that. If you still have any of your broken beads, it might be worth the experiment to try and bake them again. I'd be curious to know if they hardened up with further curing. Hope that helps.

Well, what do you know… it's not just me! I don't use cornstarch (or cornflour, as it's called here in Oz) either.

I tried it as a release agent but preferred either water or ArmorAll depending on what I was doing.

It's not a help for fingerprints with my personal way of working: when I remember to smooth fingerprints out, I can do that just as easily and quickly without cornflour as with it, and it's less messy without.

I use Kato Polyclay too which might have a bearing on the fingerprint thing, as it's firmer than some other clays.

I haven't found any difference in colour whether I bake my Kato Polyclay pieces in the open, tented, or directly covered (with batting, in my tests; I haven't tried immersing things in cornflour): light colours, bright colours and translucents all came out the same regardless, including at somewhat elevated temperatures and with extended baking times, so I just bake everything in the open now.

I can't comment on the strength of Kato Polyclay baked in cornflour compared to it baked out of it, however, because I haven't tried that. I'd decided not to bother with cornflour immersion for other reasons fairly early on in the piece. (If I was going to use cornflour as a support for complex shapes my inclination would be to place a tissue a piece of absorbent paper on top of the cornflour so that it didn't come into direct contact with the polyclay, but my style hasn't required me to do anything like that yet.)

And I haven't needed to put anything on my bead piercing tools, even the fatter ones.

So I just use cornflour for cooking. Except for the container of it I'd dedicated to polymer clay; that's still lurking somewhere at the back of my workbench, but will probably get chucked the next time I tidy it up.

Thanks for your comments Sue!

I love using cornstarch and like I said, it may be a brand thing when it comes to using it with Kato. I also prefer using the starch for stamps over water, due to the fact that moisture in your clay, especially in translucent can cause problems such as little moons and cracks in the clay as the trapped water expands with the heat.

You may be right about the firmness of Kato being such that fingerprints aren't a problem. I am looking forward to trying Kato clay soon, since some is being shipped to me at this very moment. Then I will be able to try it with the cornstarch and see if it causes me any problems.

Until then, I'm sticking with my advice. Of course everyone has a preference and you need to do whatever works best for you!

Hi Cindy,

The great thing is having access to all sorts of ideas and other people's comments, so that we can decide what to try for ourselves! I'd always want to check a technique out personally even if it had universal support. I'm not dissing cornflour/cornstarch… it just wasn't "right" (or necessary) for me and how I like to work.

I think you're probably correct about Karrah's strength problem being due to the beads not heating up properly. Kato does seem to like higher temperatures. Packages of the new formulation show a recommended baking temperature of 135C/275F instead of the original formulation's 150C/300F, but the first time I received a batch with some old and some new I didn't notice and was baking everything at 150C/300F anyway, with no ill effects or discolouration. And it was nice and strong! (Original formulation Kato baked at the lower 135C/275F is definitely much weaker compared to when it's baked at 150C/300F.)

Actually, the last time I looked at the Kato PolyClay web site, it had been updated to reflect the new formulation (new package sizes, new colour combos, new products, etc.) but it still had 150C/300F as the recommended baking temperature although it also said that 135C/275F — which is what's on the new packets! — gives "good results". I was going to ask them whether the change to 135C/275F on the packets was just to fall in line with other brands and make it more obviously safe to mix with them (i.e. 150C/300F still being their full strength recommendation), or whether full strength was actually now achieved with the new formulation at 135C/275F. But I never got around to it. Maybe I'll test it myself this weekend…

I hope you have fun when your Kato clay arrives! I love it, including how it's really firm… but then again, I'm a bit weird sometimes. ;)

Sue

Sue you are a tremendous asset around here! I'm thinking you're on the right track there with the Kato temp thing. I read that higher temp somewhere too.

I haven't talked too much about Kato on this blog because I don't have experience with it. I also haven't rushed to use it since most beginners don't have easy access to it and this blog was originally dedicated to beginners.

I have noticed more and more of the intermediate to advanced clayers that visit here using it, so have thought it was about time I ordered some online. (It's hard to have every product available out there.)

As I work with it I will be able to understand it's quirks and how it interacts with other materials such as cornstarch, etc.

For the super soft clays that most people have access to, I have found cornstarch to be a tremendous help. When I get the chance to work with Kato, I may find my advice for it different.

I very much appreciate all the information you have been sharing here. Keep it up! :-)

Hi Cindy,

I emailed Van Aken International about maximum-strength baking temperatures for the new Kato formulation after I posted above. They haven't replied yet — not that they've really had a chance to! — but I did a bit of testing this evening.

The results were startling.

I only tested new formulation Yellow. I rolled it out to the second-thickest setting on my pasta machine, cut out 5 identical pieces, and baked each of them flat on individual tiles at the temperatures and for the times listed. I let them cool naturally on the tiles, then tested as described below.

Note that the baking recommendation shown on packets of old formulation is 10 minutes at 150C/300F; the baking recommendation shown on packets of new formulation is 30 minutes at 135C/275F. I also always add 10 minutes when I'm baking on tiles so that the time "starts" about when the tile has equalised temperature with the oven, which is why my shortest test is 20 minutes at 150C/300F instead of 10. And I have temperature-tested my oven!

Test 1 – Sharp bend across the middle of the test piece

No visible damage to any of the 5 pieces.

For tests 2 and 3, I held the polyclay sample firmly in nylon-jaw pliers part way up the piece. I then bent the remainder of it back and forth as far as possible each way, and counted the number of bends it took for the damage I was testing for to show.

Test 2 – Bend until the surface has a visible crack

135C / 40 mins … 1
135C / 70 mins … 3

150C / 20 mins … 60
150C / 40 mins … 85
150C / 70 mins … 60

Test 3 – Bend until broken all the way through

135C / 40 mins … 7
135C / 70 mins … 17

150C / 20 mins … 280
150C / 40 mins … more than 400 (I got tired of bending it!)
150C / 70 mins … more than 400 (I got tired of bending it!)

Colour change

135C / 40 mins … minimal; very slightly darker than raw clay
135C / 70 mins … darkened slightly but noticeably

150C / 20 mins … no colour change at all; identical to raw clay
150C / 40 mins … darkened slightly but noticeably; about the same as 135/70
150C / 70 mins … darkened noticeably

So I'm sticking with 150C for Kato (unless I've got some Premo Frost on the piece too), in spite of what the new packets say!

Cheers,

Sue

Sue, once again I am thrilled that you would share your testing results with us! That is incredibly helpful for everyone! THANK YOU!!

For those of you who do not use the metric system here's the conversions:

135C = 275F
150C = 300F

Us Canadians use both Imperial and Metric but for many of you Americans, I thought this may help. :-)

I've been using only Kato clay – since it's made by a local here in Colorado. I have found that if I bake it at more than 265F, the translucent yellows. But that may be because I live at 9,000 ft. and things work differently at this altitude.

Yeah I wonder about that Besty! That really could make a difference. I'm just a few feet above sea level, so I'm quite curious about that. Do you find you have to adjust temps when you bake regular food?

@ Sue

Thank you for sharing all these results with us! Getting the Kato clay out and firing up the oven this weekend, and you just saved me a ton of work and time!

My wife and I just got started in polymer clay today. I noticed through your tutorials that you use corn starch to keep things from sticking ( a problem I had with my work surface today) – I am curious, does the corn starch bake off in the oven – is there any residue, what do we have to watch out for?

Oh yea, we have the bug and are so excited about this new found hobby.

Thanks Cindy.

Cindy,

Found the answer I was looking for after you had sent me an email directing me to search your site for post. Here's a link to the answer: Baking Beads On Cornstarch

Thanks a million.

Doug

That is great Doug! Glad to see you found the answer your needed and thank you so much for passing it along to everyone else. That is fantastic help!!

Sometimes it can take me a day or two to get all these questions answered and I hate to leave you hanging. You will find that there is a lot of info here at the blog now and that the search box will often help in finding what you need. Looks like it worked for you!

Honestly, after fourteen years of working with polymer clay and being active within the polymer clay community, I have grown weary of the "Thou Must Not Let Fingerprints Show!" mentality.

Certainly, there are pieces that benefit immensely from a very careful smoothing over, and obsessive sanding and buffing. But there can also be pieces that have added charm with a stray fingerprint or two.

I think the lesson is to remember that there is no "One True Way" of doing things, and you need to think about what works best for YOUR work, YOUR style, and YOUR creation.
.

I can respect that Julie. Probably the most important thing for any bead maker to remember, is to stay true to your own style and to decide what is or isn't important to yourself as far as how you go about making them.

The reason I am such a big advocate for sanding and polishing your polymer clay beads, is because so many beginners don't realize how much, just a little bit more effort in finishing, will improve the quality and professionalism of their end product.

You don't even have to have good taste in design or color, or even have any talent yet, but if your bead is carefully finished, it will still look good. This little step helps build the confidence to create a more skilled product as they progress through their bead making journey.

After all you can take an ugly little rock and polish it up to become quite the little gem!

As far as leaving the odd little print behind, that is perfectly OK. Some styles actually lend themselves to a little imperfection.

Polymer Clay Bead making is about getting the satisfaction of creating something wonderful from a little lump of plastic clay and having others be impressed enough to want it for themselves.

How you go about it, is always up to you! :-)

Oh yes – there are times when nothing but that gorgeous sanded/buffed finish will do for me, and I still remember the thrill of bringing that shine up the first time I sanded and polished some beads! =)

I know what you mean Julie! I still get that thrill!

A little tip for molds. I use the mold for resin pieces. I put Saran wrap in the mold, making sure it is smooth with no creases and fill it about half way with p.c. I then pull it out and have the shape I want. I have sold bracelets with the square mold. I use the square, crystals and metal beads. I don't sell my pieces on purpose, people seem to like them. I consider myself a novice, but I've learned so much from you. Bless you.

Sandra that is so exciting, good for you! Neat idea for using the resin molds for your polymer clay. Good tip for lining with plastic wrap first! Thanks for sharing!

Can you use Johnson's baby powder instead of cornstarch to bake beads with?

I think you can Ken, but I would look at the ingredients to make sure they haven't put any oils in the powder that may effect the clay.

Oils? As in Aloe? I can't find wipes with just water, everything has to have Aloe and some other junk. So paper towels and water win.

By the way, I have read in various places that baby powder can be used – but like you say Cindy, check the ingredients.

Speaking of which, I sat and watched my oven and thermometer and found the "sweet spot" on the oven temp setting that equates to 275 F. SO I cooked / baked, and low and behold, that same Premo Fluorescent Red came out brownish for the second time. Is that norm for that color/brand color?

I finally got my head out of the sand and bakes my flat pieces between 2 tiles. What do ya know – they came out perfectly flat. Gee, who'd a thunk!?

I am finally finding my niche early on. Will have about5 things to add to our Etsy site tomorrow. Ahhh, joy at last.

The oils in the baby wipes don't matter Doug, because they aren't really in prolonged contact with the clay. I just use them for wiping my hands and the surfaces I'm working on, to clean them.

Oils in baby powder are different because if you're baking in it, the clay sits in the powder for a long time and the oils may be transferred to the clay.

Back the temp up a bit when you bake the Florescent clays if you are still having a problem with them browning.

Yeah the Ceramic Tile Sandwich works pretty good, doesn't it!

Glad to hear you are finding your niche! Can't wait to see your stuff posted on Etsy. Way to go!

Thanks for that info on the wipes versus the powder. I feel much better now knowing I don't have to stress over that part. My wife, Cynthia (who handles the Twitter part for us – twitter.com/ga_mtn_crafts) also says thanks.

I bake outside to keep the temperature down in the house (funky A/C) and yesterday it was a cool 91F outside – but I monitored the oven for the entire time.

Haven't got my new stuff baked yet, but will today and then will get it sanded-buffed-polished and photographed.

One thing I did find out is that things look better with a second coat of floor wax. However, You have to wait at least 8 hours to re-wax to let the initial coat cure, otherwise it just softens up the first coat and looks gooey. So, I now coat either when I first get up, or just before going to bed.

Good point about the second coat Doug. Thanks for passing that info along!

@Doug — Do you put the paper tent over your pieces while baking? I started doing that and it made a big difference. The heating element was the culprit for over cooking my clays. I guess in my toaster oven, the clay is just too close to the element – and that's to be understood.

Good luck!

Great point Brenda! I always tent my beads as well. Haven't had a scorched bead since!

cindy, do you know how to make own polymer clay at home? in indonesia the existence of polymer clay is very rare, but as for certain it is so expensive

No I'm sorry dee, I don't know how to make polymer clay at home. Even if there were a recipe for it, I do not think that the same quality as the commercial brands would be possible. I'm sure there must be an online source you can purchase your polymer clay from that will ship to you in Indonesia. Perhaps others from your country who read this blog, could pipe up with some suggestions. It is so fun to hear from all of the international visitors that follow the blog.

I remembered Karrah's comment (above) about her Kato beads being really weak when baked in cornstarch, and thought I'd mention that I've just seen the same problem myself.

I've been converting some of Cindy's gorgeous Premo colour recipes to Kato, and in doing this had found that SOME of my Kato colours were shifting a bit during baking, away from violet and towards blue. So I thought I'd bake a sample immersed in cornstarch to see if that made a difference (tenting doesn't). I mixed up one of the recipes that I'd seen colour shifting with and cut out two colour chips, each 41mm long by 28mm wide by 1.8mm thick. One went onto a 10cm white tile for baking like I normally do, and the other went into a small (150mL) clear pyrex dish with 1.5cm of cornstarch in the bottom, and was then covered with another 1cm of cornstarch. Both then went straight into a 152C/305F oven for 25 minutes (recommended baking time is 150C/300F for 10 minutes on the oldest and newest packages; the 135C/275F on some packets in the middle of that is apparently an aberration, to use my words instead of Van Aken's), were taken out and left to cool naturally.

When I took the chip out of the cornstarch I found that it hadn't shifted colour, but it was so weak that I could practically break it by looking at it! Well, not QUITE that bad, but almost. Very light finger pressure was enough to snap it into small pieces, and I can actually pulverize those pieces completely when I press hard. However, the chip baked on the tile was as strong as ever (taking several hundred full bends with pliers to break it, in line with what I'd noted in the temperature/strength test info I posted above).

25 minutes is two-and-a-half times the "recommended" baking time as printed on the packet, although it's about normal for me. It was only a small dish of cornstarch so there wasn't much extra thermal mass — certainly less than the tile the other sample was baked on — but it does have an insulating effect.

I'd said earlier in reply to Karrah's comments that I hadn't tried cornstarch immersion. But now that I have, Cindy's guess that it might be a brand thing to do with Kato looks like being on the mark. I'll do some proper testing in the next week or two and will post the results (e.g. is it possible to get decent strength when Kato is baked immersed in cornstarch; if it is, how long does it take… and does that pesky colour shift return when the strength does!) but thought I'd mention straight away that cornstarch immersion doesn't seem to be a good idea for the Kato brand.

As always, it is so fantastic to hear about your testing results Sue! I had planned to have a 'In the Lab' type segment in the blog for testing, just like this, but as it has gotten busier and busier around here, I hadn't found the time. So having you share your findings has been a tremendous asset!

Now, I have found that the amount of time the clay has been sitting in the cornstarch, prior to baking had a big effect of the clay strength when baked. (Possible leaching of plasticizers from the clay, due to absorption qualities of the cornstarch.) I found clay that went straight into the oven after immersing in the cornstarch was fine, however if it sat in the starch for any length of time it become weak.

How long did your samples sit in the starch before baking? I would be curious to know if this could have possibly been the source of the problem or if indeed it is a brand or formula issue.

The time delay between immersing the sample in cornstarch and popping the whole thing into the oven was less than 10 seconds. ;D I'd seen your comment before about leaching and made sure that pre-baking leaching wasn't a factor. I don't know whether there's some "super-leaching" effect going on DURING the baking and will test that too, but I've never had deliberately-leached samples baked normally get that weak (I'd made a few heavily-leached sheets of polyclay when trying to replicate your deep crackle faux raku effect, before that video was published).

Hmmm, interesting. I am a little at a loss here. I know that Donna Kato recommends putting clay in cornstarch as well, so I'm not sure what is happening here with your clay. I guess, all you can do is keep testing and see what works best for you. I suppose it could also be a problem with one particular batch, though it does sound like you're having no problems with it outside of the cornstarch. What we need is something as soft and as fine as cornstarch but that is completely non-porous. I wonder if something like that exists? As always, keep us updated. I love getting your 'Lab updates'! :-)

I'll definitely post an update once I've done some more testing, although it will probably be two weeks until I have enough time to do that properly.