Polymer clay, or polyclay, is a fun and creative modeling material that you can mould and bake at home. Unlike Air Dry Clay, polymer clay needs to be baked in an oven to keep its desired shape and become firm.
Ideally, you will need a polymer clay oven and know how to use it. However, you can also bake polymer clay projects in your regular home oven. In this article, I’ll share tips on how long you should bake polymer clay crafts, the right temperature to use and how to prepare for baking.
Things to Keep in Mind
There are three main things to keep in mind when baking polymer clay crafts. These are temperature control, baking duration and position in the oven. If you keep these three things in check, you should have no problem with baking polymer clay artwork.
Polymer Clay Baking Duration
Many crafters worry about the correct baking duration and rightly so. If you bake it for too long, there is an added risk of discoloration. If you don’t bake the clay long enough, you will get a somewhat fragile finish.
A number of clay art professionals will tell you to follow the instructions on the packaging. If the package says 30 minutes then bake it for 30 minutes and no more.
While this sounds reasonable, it isn’t always practical. The shape and size of your craft must be taken into account as well.
A small, feminine statute with fine details will bake nicely in 20 minutes at the ideal temperature. But if you craft a large turtle or elephant you will need to bake it for longer.
What’s more, baking times for different brands differ. Some suggest baking polymer clay for 30 minutes, while others suggest 10 – 15 minutes as optimal. Here’s a breakdown of baking times from popular brands
- Cernit: Approximately 30 minutes
- Fimo: 30 minutes maximum
- Kato Polyclay: 10 minutes
- Pardo Art Clay: Minimum of 30 minutes
- Premo: 30 minutes per 1/4″ (6mm) of thickness
- Sculpey: 15 minutes per 1/4″ (6mm) of thickness
In my experience, brands that suggest baking times by taking account of the thickness and size of your craft tend to be more accurate in their recommendation.
It should be noted here that polymer clay tends to become stronger when it is baked in the oven for a long time. The heat solidifies the bonds inside the clay molecules.
Most types of polymer clay are not burned or damaged when they are baked for a long time. This is because the clay is oil based. There is no risk of water evaporating from the clay or cracking.
Polymer based Air Dry Clay is an exception though as it is water-based. However, you shouldn’t be baking ADC polymer clay in the first place.
The only limiting factor for baking is the color of your craft. If you bake polymer clay for too long, it will being to darken and turn brownish. This shouldn’t be a concern if you are planning to paint it later.
However, if you are working with light or translucent polymer clay then keep this in mind to avoid ruining your project.
Also, if you live at a high altitude, then your baking time will be different. As general rule of thumb, baking times will be longer and you will need to use a higher temperature as well.
If you live at an altitude of 3,000 feet for instance, you will probably need to bake ten minutes longer and at 5-10 degree higher temperature. A bit of trial and error will help you determine the ideal baking conditions.
Temperate Control for Polymer Clay
Before you start putting your projects in the oven, make sure that you fully understand how it works. You should have a fairly good idea of how hot it can get and temperature control consistency.
Get a good separate thermometer to test out how hot your oven can get and how you will manage it.
Not all ovens are created equally and understanding how it works will go a long way in preventing frustration later.
Convection ovens, i.e. ovens with a fan and exhaust system, are much better at maintaining the required temperature because the air is blown out when it gets too hot.
If you don’t have a convection oven, you will need to keep track of the temperature and turn it on and off manually.
Remember, there is a small chance that your polymer craft may burn and turn brownish if it gets too hot. If you are using an armature, there is also the risk of bending the metal wires if it gets too hot.
On the other hand, if the temperature doesn’t get high enough, your craft will not cure to the desired level.
There are some ovens that turn off on reaching a very high temperature. The heating element only kicks back on after the oven temperature drops significantly. If this is the case with your over, it might be helpful to place a heat sink in the oven to keep the temperature in the required range.
Heat sinks absorb heat when the temperature is too high, and then release it when the temperature gets too cold, allowing you to maintain a consistent temperature. Ceramic tiles on a rack work pretty well as heat sinks.
Here I have a trinket bowl ready to bake and a self portrait my seven year old granddaughter made. I’ll have to bake these in two batches or remember to take the bowl out before the doll because the bowl is so thin and the doll is 3/4 inches thick, and will need a longer bake time.
Position in the Oven
When you place your polymer clay project in the baking oven, try to keep the center of the piece as far away from the heating element as possible.
You will need good air circulation inside the oven. This will ensure that the heat is distributed evenly inside the oven and your craft dries equally from all sides.
Keep your polymer clay project at the center of the rack. It must be equidistant from the elements, and away from the oven’s walls.
You also need to keep your craft away from the base of the baking tray. The metallic tray will get very hot during the baking process. This can cause warping in your project.
If you are worried about this, you can use aluminum foil pans for baking your crafts. Here’s how to do it.
- Take an aluminum pan and place a ceramic or porcelain tile inside.
- Place a plain sheet of scrap copy paper on top of the tile.
- Place your polymer clay craft on the paper.
- Cover the first pan with another aluminum foil pan.
- Place binder clips on the edges of both pans to secure them together.
- Put the pans on a baking tray and bake.
This will work if you have a big oven and your craft is small enough to fit inside the pans. It will take some trial and error but ensures that best results in case your oven temperature is hard to maintain.
Out of the Oven
Polymer clay remains soft while it is baking in the oven. It will also appear and feel soft right after you take it out.
The clay will begin to get hard as it cools down. Usually this takes 6 – 10 hours. If you are planning to sand and varnish the craft, wait at least 10 hours before you do that.
If it comes out with some smudges or marks you can remove them with sanding. This will give the polymer clay crafts a professional look.
Other Tips for Baking Polymer Clay
- It is important to condition your clay properly to get the best results. Make sure that air is not trapped inside the clay as you pass it through the pasta machine. If air bubbles are trapped in the clay, they will expand during heating and show up as bubbles near the surface.
- Avoid adding water or water-based products in your polymer clay projects. The water molecules get trapped inside the clay and turn to steam in the oven. This is the most likely cause of cracks during baking.
- Try to smooth out the surface of your project before you bake it. Any scratches, finger prints or dents should be removed before your clay goes into the oven. It is possible to smooth them with sanding, later. However, what takes one minute of smoothing before baking can take 10 minutes of work later.
- Try to keep as much metal out of the oven as you can. Metal items can cause unpredictable temperature spikes that can ruin your work.
- Put a big tile in the oven to act as a heat sink. It will absorb a lot of direct heat from the heating element. This helps keep the temperature stable while baking.
- Try to use the middle shelf in your oven for baking. This puts it at an equal distance from the side, top and bottom. If you can’t choose the middle tray, put it near the bottom on a ceramic tile. The tile will offer some protection for the heat.
- Make sure you leave a window or two open while baking, as the polymer does emit fumes while it bakes. For this reason, don’t use the same oven for baking food until the oven cools and you can leave the door open to ventilate any remaining fumes.
Polymer clay is great for making all kinds of crafts and artwork. One great thing about this clay is that you don’t have to bake it right after you finish your prototype. Polymer clay is generally oil-based and maintains its moisture for months before you need to bake it.