What Do You Put Inside of Large Polymer Clay Sculptures?

Larger polymer clay structures require internal support to cut down on the amount of clay used and sometimes as a way to make the entire piece more durable by providing a strong frame.  

There are a variety of materials that are commonly used for armatures inside of polymer clay. For example, the most common armature is made out of crumpled up aluminum foil. Scrap clay and polystyrene foam with a compatible melting point are also options that get frequently recommended. 

What is the purpose of an armature in polymer clay?

The most common reason that people use an armature is to cut down on the amount of clay that is used, which decreases the cost and overall weight. Depending on the material the support is made out of, it can also provide more structural integrity for the piece if it isn’t intended solely as a display piece. 

An armature can be either permanent or temporary — meaning it can be dissolved or otherwise removed after the clay is finished baking. A permanent armature provides internal support for the piece and it also cuts down on the overall project expense because less clay is used.  For example, a wire frame inside of the piece can help strengthen thinner pieces (like arms or tentacles). 

Is foil the best armature for polymer clay?

Aluminum foil is readily available, lightweight, cheap, and able to be shaped into all kinds of custom forms to fit inside of sculptures making it one of the best permanent armature materials for larger projects. Clay is also easy to shape around armatures made out of foil. It’s my go-to material most of the time. It can also be combined with a wire frame, as well. It may not be as practical for really large sculptures (like for pieces that require a baseball sized core) just because it would take so much foil to make a decent sized ball. 

Can you use polystyrene foam inside of polymer clay?

People do use some types of polystyrene foam as armatures, however, it can’t be used as-is. The foam needs an aluminum foil layer wrapped around it to prevent it from shrinking when the sculpture is baked. Keep in mind that there are different types of polystyrene foam — not all will perform as expected when used for an armature so you will need to experiment — and each one has a different melting point. It’s important to check to see if the melting point is compatible with the clay brand you’re using so that it doesn’t melt and give off noxious fumes. 

Do all polymer clay sculptures need an armature?

An armature is not a requirement for many projects — small sculptures (smaller than the size of an egg or so) don’t need anything inside of them. As an example, an armature is not necessary for beads. 

Does scrap clay make a good armature?

You should definitely make a point to save bits and pieces of failed projects or excess parts of canes. Scrap clay makes a great filler to bulk up the inside of a bead, and it can also be used inside of smaller sculptures (like for the head). 

Can you use crumpled paper as an armature?

Unwanted paper, old newspapers, and cardboard can make a good alternative if your only goal is to decrease the amount of clay used and the piece won’t be exposed to water. Paper pulp and paper clays can be used to make custom interior shapes. 

Is there a benefit to making large clay pieces hollow?

The decreased weight of a piece can improve the way that the parts sit together, decrease the cost of the project, and make it so that larger jewelry pieces are more comfortable to wear. A hollow interior (that is filled with a foil or wire support) will be easier to fully cure than a thicker piece. The easiest way to make a hollow piece is to separate it into two sides, both can be baked by draping them over a foil support, then joined together after they are hardened.

Why won’t my polymer clay stick to the armature?

Polymer clay doesn’t stick well to smooth surfaces — this is why crumpled up foil works so well! If you’ve made a wire support for the piece, make sure you take time to surface prep the frame. This just means roughing it up a bit by running some sandpaper over it. 

Alternatively, you can add dimension to the wire by twisting multiple pieces together to create the frame. This will give the clay something easier to hold onto, especially if you also run some sandpaper over the twisted wire, as well. Hammering a thick piece of wire so that it has texture and varying outer dimensions can achieve a similar effect. 

People also have success wrapping the wire in masking tape or coating it in a layer of white glue so that the clay has a rougher surface to stick to. I don’t personally use this as a method – I usually just opt for sandpaper because it’s something that I always have on hand.