How to Bake Polymer Clay Like a Pro (Plus Do’s and Don’ts!)

In this post I’m going to talk about the in’s and out’s of how to bake polymer clay, and do it like a real pro! So if you’re looking to paint sculptures with a substance that is fun and low-maintenance, not to mention being freed up from the need for an expensive kiln, I think you will love this.

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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No Kiln, No Problem…You’re welcome😁

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.

Be that as it may, there’s a lot of territory to cover, so let’s get to it!

Preparation

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.  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.

💡TIP: Another item I would consider, is the use of a pizza stone on the bottom rack of your oven, it can create a “heat sink” effect which will help your clay project set more evenly.

Arranging Your Project

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 prefer not to use them.

I do have a few glass Pyrex dishes when I looked it up it said they have a heat threshold of about 350 degrees.

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.

If you have very small objects like beads, there are several ways to tackle it so they won’t roll around. One way is arranging them on s bamboo skewer, which I have done, another way is to fold a piece of heatproof paper into an accordion shape and set each bead on one of the pleats, and a third popular approach is to fill the tray/plate with a layer of baking soda. All of these have proven to work well.

Cover Your Project

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.

“Tenting”

Another thing to practice too, is the act of “tenting” your object before baking. Tenting, put simply, means to create a structural arrangement with the aluminum foil which serves two purposes – keeping the object from getting possibly scorched from being too close to the heat source, and improving the ventilation around it.

Bend the top piece of foil so it has a peak in the middle, just like an actual camping tent –  and place it over the object, prior to putting it in the oven.

Temperature and Time Settings

Different brands have different recommendations for times  and temperature settings,It certainly is confusing when you come across these variations. 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“. For reference I’ve included the most popular brands’ respective settings here:

Sculpey

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, all of this is explained on the proprietary website .

Fimo

The brand Fimo has a lower temperature setting than Sculpey. Here is what the labeling on the back of a package of Fimo Professional offers as guidelines – “230 degrees F max”. 

Kato Polyclay

I have not used Kato, but from what I have read/researched about it, it has a higher heat threshold and recommendations for the oven setting stated 300 degrees F. Kato is a much denser clay than the other brands.

Can you Over-bake Polymer Clay?

A lot of aspiring clayers do ask this – how long is too long? It’s a sore spot, apparently, so let’s look at that now.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.

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.

How Safe is Baking Clay in a Conventional Oven?

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.

Special Considerations…

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.

Can You Bake Clay in a Convection Oven?

Absolutely, and I would encourage you to do so if this is what you own. We recently replaced my old stove and upgraded to a convection model, and I find my clay ventures do just as well if not better. The mechanism is different – there is a fan in the back ( Not sure if you can see it in this picture, but that’s the best angle I could get.)

The heat distribution from the fan movement is more even, resulting in less chances of dark or under-cured spots. One pro tip, is I wouldn’t fill the pan with substrate, like sand (some professional clayers do this to “seat” small objects) as it could blow around.

Don’t Handle Clay 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, lol….

Haste makes waste. So if I’ve been baking clay late at night, say ten or eleven, I set the oven for about 20-25 minutes and let it cool overnight and it is ready for me to prime and paint the next day! Same with the toaster oven.

Final Thoughts…

Also you may already know this but I’ll state it clearly: please do NOT attempt to microwave your clay! (I can’t believe people actually ask this, but they do.)

==>>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.

But anyway, now you know all about the ins and out’s of how to bake polymer clay successfully and steer clear of common (or dangerous) pitfalls.

============Good luck to you and let me know how it goes! Comment below.=======