Properties of Different Clays

written by Mike Brent

The purpose of this thread is to help newcomers determine what kind of clay they need to look for. I'll kick things off, and feel free to add anything else that seems appropriate.

Plasticene is what's generally referrred to as "modeling clay". It's also known as Plastilena (Italian spelling I think) and I've sometimes seen it called "plastercine" (Brittish maybe?).

It's an oil-based clay that never hardens. This is the kind used for "claymation". Actually that's not entirely true, because in most so-called claymation films most of the bodies of the puppets are actually made from different materials and only certain parts are made from plasticene, namely those parts the animator needs to manipulate like the faces and hands.

The Van Aken brand is considered one of the best. They make a line called Claytoons that comes in a great range of colors and should be available at many art supply and craft stores. There is also Roma Plastilena, an Italian clay used by sculptors that comes in varying degrees of hardness but only in a few colors. Chavant is another manufacturer of plasticene, and also make varying grades of hardness, but again it's more for sculptors and doesn't cme in the range of colors a clay animator would need. These clays are good for making prototypes that will be used for molds.

DO NOT PUT PLASTICENE IN THE OVEN!!! It will only melt into a greasy puddle and create a fire hazard. People sometimes get mixed up and think all modeling clays will harden if baked the way polymer clay does, but that's not true. Read the label... if it doesn't say to bake it, then don't.

These are similar in some respects to plastilene, but once done sculpting with them, you bake them in the oven and they harden into a plasticlike consistency. Popular brands are Super Sculpey and Sculpey 3 (stay away from the original white Sculpey, it's sticky and hard to work with), Sculkpey Premo which is their premium line, Fimo and Cernit in Europe (I believe both are very hard and difficult to sculpt with until they've been "conditioned" either by running through a pasta machine a few times or beating with a club for a while).

People often ask about using a polymer clay to do clay animation with, as a substitute for plasticene. This is not recommended, because these clays all require some degree of conditioning prior to working. If you let it sit overnight and try to bend it the next day, it will crack. The Sculpey line is softer and requires less conditioning than the European brands, but a pasta machine ($40.00 or less on ebay) is still recommended, or else get ready to knead it in your hands for a good while.

These include Magic Sculpt, Aves Apoxie Sculpt and Apoxie Clay and also there are some sold at hardware stores for use in plumbing and various household tasks... one good line being Devcon. Epoxies come in two parts that must be thoroughly kneaded together to begin the chemical reaction that will result in their hardening. You CAN mix them in your bare hands, but it's not recommended. You have to mix for a while, until the color becomes completely even and it begins to feel soft and warm. A good idea is to wear some rubber gloves, at least while you're blending it together, or at least have a cup of water handy so you can clean it off your hands. If it starts to harden on your hands it will take a few days to pick it all out of your skin, and it doesn't feel good! After you have it thouroughly mixed, it's a good idea to let it sit for a few minutes (maybe while washing your hands) and it will solidify a little... at first it's too soft to work with.

Generally speaking the hardware store varieties will come with an "open time" or "working time" of anywhere from 5 minutes to maybe 20 minutes, meaning you have that long to manipulate it and then you need to keave it alone and let it set up. If you keep working it you'll only mess it up. The artist's grades, like Magic Sculpt and the Apoxie line give you a longer working time, maybe up to a few hours. The thing to keep in mind is how long do you need to work on your sculpt.... if it can be done in an afternoon or in a few minutes, an epoxy putty will work, but if you need longer then go with a polymer clay.

Just as an aside, I'll mention a few specialty clays here too. For making silicone molds you want to use a clay that doesn't have sulpher in it (most plasticenes do). Chavant makes a brand called Chavant NSP (Non-Sulpherated Clay), and there's also a brand called Kleen Clay that has no sulpher.

Also sometimes called WED clay (Walter E Disney, who created it for the Disney studios). This is a fast-drying air dry clay that is used for making maquettes (rough sculptures to determine pose and details for a more complete work). Like traditional ceramic clays it must be kept moist by spraying it with water and covering it with a damp towel and maybe a plastic dropcloth overnight so it doesn't dry out. It is very soft and works like butter... but I find it's like working with mud and seems to suck the moisture out of my hands leaving them feel extrmely dry. I'd say wear rubber gloves or work it with tools. Wter clay is really not at all suitable for clay animation, but could be useful for making props or set pieces, or maybe making heads to be used for silicone molds.

Here are a few online sources for some of these clays...

The Compleat Sculptors clay index page

Mr Art carries the Claytoons range of Van Aken plasticenes and also Fimo Soft, which is supposed to be a vast improvement over the harder original formula, more like Super Sculpey in consistency.


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