In this post I’m going to talk about the in’s and out’s of baking polymer clay. I know there’s a lot of conflicting info out there, and sometimes you may only have the directions on the package to go by but they may not go into detail about special instances.
For example, the period of which to cure a larger object will be different from that of something small like a set of beads. Well let me give you the benefit of my experience as well as some good do’s and don’ts to keep in mind.
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Polymer clay is made from polyvinyl chloride which gives it a certain tensile strength and ability to withstand heat. It is called polymer clay for this reason as that’s the bread and butter of it. These attributes make it perfect for home use and why it bakes up nice and firm – so it does not need to be “fired” at high temperatures.
Generally speaking, baking instructions run along the lines of this verbatim: “Baking at 275 degrees, for 15-20 minutes for every one-fourth an inch of clay“. Well, that is a good rule of thumb, but there are a lot of other things in between to think about.
Preparation, no doubt, is going to be the second most important thing after baking. Don’t sweat it; it’s just going to be a few precautions! The first thing includes: Choose the middle oven rack – this will prevent your object from being too close to the heating element.
Second – Preheat your oven to the time provided on your clay’s outer wrapper. Since different brands may have different recommendations for times (for example, Kato Polyclay has a wider heat threshold than Sculpey and Fimo) so this part is crucial. You may want to think about using an oven calibrating device like an oven thermometer as sometimes getting the “right” amount is not an exact science.
Dishin’ it out
I use Corning Ware dishes to arrange and seat my projects; they’re sturdy ceramic and highly trusted cookware. I don’t think I would use glass dishes, some of them tolerate less heat and although you won’t be baking clay at high temps I just wouldn’t.
Line it with aluminum foil, or you could use parchment paper. I would use a “newer” sheet of foil than I’m using here…I did some crinkle-texturizing on the outside of this wall decoration intentionally so I was OK with its appearance.
Carefully arrange your project in the middle. Sometimes figurines are tricky, depending on their height. I’d have them laying down in the pan. I know I’d always poke and prod it to make sure small or delicate parts would not collapse in the oven because if they did I wouldn’t be able to straighten them back.
Don’t forget to cover your project in the works, too, with something like aluminum foil. I have had a few objects to show brownish spots, and at first, I blamed it on doing too much oven time – but that wasn’t the case. It was being a little close to the heat source uncovered.
Temperature and Time Matters
The brand I use the most – Sculpey, recommends a temp setting of 275 degrees F, for pretty much all of the types…which I do uphold. I also notice the proprietary website always reads something to the effect of “do not overbake” I’ve heard some people say you can bake clay longer than 20 minutes, and do. I think it depends on the size of your project.
Can you overbake polymer clay? A lot of aspiring clayers do ask this. It’s a sore spot, apparently, so let’s look at that now.
However what I’ve discovered is that the temperature is more important to be mindful of than the length of time spent baking. The correct threshold of time is 275-300 degrees to properly cure the clay and avoid burning. I’ve read that the clay will burn at 350 degrees F. If your project is smaller, 15-20 minutes is fine, if its bigger – I think you can go up to 30-35 minutes as long as the temp remains stable at 275-300. Some people will bake a few items even longer.Polymer clay will burn @ 350 degrees F...just FYIClick To Tweet
It certainly is confusing when different clay brands tend to have differing instructions, and set times and temps listed on them. For example Fimo (shown here) recommends a lower set time. than Sculpey….
Well, let’s be honest -a lot of warnings on product labels always sound very ominous. We could blame that on this litigious society. The thing to keep in mind is that guidelines are written in a general approach -to apply to pretty much everyone handling it, regardless of experience level. So disregard (a little) and bake your object for as long as it is needed.
Baking in a conventional oven-is it safe?
It is, and I do. And I’m doing just fine. The clay does emit a slight odor, but its not unpleasant while baking. I also turn on the ventilator above afterward. If you are concerned about toxic fumes for whatever reason – I am not sensitive to smell, but I know some people are – I’d use the fan and open a window, or think about getting a designated small oven, either a toaster or convection style -for all your clay baking needs.
You can find some small ovens that are designed for this purpose exclusively, or you could purchase a small oven and just “designate” it. If you want you can even move it to another room in the house like the garage. if you need further ventilation.
You can also use preformed molds or wire armatures in the baking of your projects easily; since the recommended oven temp is below 300 degrees there is no concern for possible hazards.
When baking, how much to err on the side of more or less depends solely on your unbaked item’s square inch volume. I tend to “hollow out” many of my projects for this reason; it makes the process consistent.
Don’t Handle Projects When Still Hot
Another rule of thumb to adhere to is not to handle your projects too soon post-bake. There are still active plasticizers present in the clay that can revert to their “soft” stage and be more prone to breakage if you interrupt the process, or reach for it with a hot pad in hand right away when the timer dings. (Kind of like when people say a cake will “fall” if you peek in the oven in the middle of the session…)
Refrain from doing that – just chill out on this one, and let it cool in the oven so it will be fully cured. When I hear the timer go off , I turn off the oven, and just go about my business. It’s not going anywhere, and I know my cats won’t be able to mess with it either. Haste makes waste. So if I’ve been baking clay late at night, say ten or eleven, I set the oven for about 20 minutes and let it cool overnight and it is ready for me to prime and paint the next day! Same with the toaster oven.
Also you may already know this but I’ll state it clearly: please do NOT attempt to microwave your clay!
It ain’t made for that, peeps!
And I don’t think you can boil it either. Well, you might could, but it would probably be waaaaaay too time consuming. For one thing water boils at 212 degrees F, and you need at least a 275 degree setting, so that rules out as inefficient. Don’t try that one either.
============Good luck to you and let me know how it goes! Comment below.=======