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Polymer  Clay Teacher's Primer

Basic Guidelines for Instructors and Users of Polymer Clay - Margaret Maggio

Polymer Clay Characteristics:

Polymer clays are plastic. Every polymer clay is made with a combination of PVC, plasticizer and fillers. The types of plasticizor and fillers and their ratio determine the feel of the clay when raw and the strength of the clay when baked. This means that every clay has unique properties because the formulas used for each clay are different.

Recommend that you always do a test piece you will break because each clay has it’s own structural strength and the only way to know is to test. Baking has a lot to do with it.

Margaret Maggio and Marie Segal are continuing to work on this information. More to follow as the testing and write up is done.

Basic Safety Guidelines for Working with Polymer Clay:

  • Use polymer in a dedicated place where it will not travel through a living area and possibly contaminate food areas.

  • Use polymer in a well-ventilated area; plasticizer is odorless and evaporates.

  • Bake in a dedicated and even heat source, convection is preferable, and do not allow the temperature to raise above the recommended temperature on the packaging of the clay you are using. Burning polymer is immediately deadly when inhaled as was discovered when polymer seat covers produced toxic smoke in plane crash fires. Stand away from the oven as you open the door to avoid inhaling the fumes. Do not bake in your home oven. Some people have dedicated a large covered roasting pan to polymer and put their raw polymer pieces in the roasting pan so that the plasticizer which would otherwise collect on the inside of the oven will collect on the interior of the roasting pan. Never should this pan again be used to prepare food. If polymer is baked in a home oven, the residue from polymer baking should be baked off at 450 for 20 minutes with all windows and doors open and people and pets out of the house before using the oven for food.

  • Latex gloves are recommended as a precaution with frequent use of polymer clay to prevent plasticizer from entering the body through invisible cuts in the skin. Oxyfresh skin barrier is recommended, especially for children.

  • Keep your hands away from your face, mouth and ears when using polymer.

  • Don’t eat food in the polymer work area.

  • Always wash hands thoroughly after using polymer with a soap which will take it off, such as an aloe based liquid soap or orange oil and pumice liquid soap.

  • Anything that comes from the kitchen for use in polymer clay work should never be used for food thereafter.

  • ADTMD/MSDS information sheets are available upon request for U.S. products and some imports. It should be noted that complete tests of the polymers we use in the way we use them has not been done, and the real and long-term consequences of the use of polymer clay is not known. There are many other tests which are related that indicate low risk.
Oven Etiquette in a Group or Class Setting - Pier Voulkos
  1. Learn basic operating instructions for the oven you are about to use. Toaster ovens, convection ovens, turbo ovens, and regular home ovens all have different safety concerns.

  2. Temperature and length of baking is critical. Never assume that external knobs for ON and OFF and temperature control are accurate. Even if you have previous experience with an oven “just like this” always use additional internal oven thermometers.

  3. Never open an operating oven to just throw your piece in. Even if there seems to be plenty of room.
    1. you may upset a critical baking schedule it could be an underbaking schedule, a translucent clay schedule, or the other extreme of a bumping schedule.
    2. slow cooling may be important and opening the oven door may be a problem.
    3. Only remove another persons work from the oven with their permission unless it is totally cool and can be handled without oven mitts
  4. To preheat or not to preheat????
    1. Some clays and techniques benefit from a cold oven start. Others, a pre-heated oven is fine or necessary.
    2. Some ovens can handle a cold oven start, some a preheat is necessary.
    3. Most toaster ovens and some convection ovens have cycling thermostats, that can be difficult to manage. Rapid spikes in heat can be controlled by preheating to the proper temperature. Minimal opening and closing of the door also prevents heat loss, and helps keep the heat steady so that the thermostat is less likely to oven react.
    4. Large home ovens and some convection ovens (Farberware) have thermostats that gradually increase temperature and keep a reliable steady heat. Work can be placed in the cold oven and brought up slowly to the correct temp and helf there. Intentional bumping up of temperature is achievable in these ovens.
    5. Bumping a toaster oven is NOT recommended
  5. Safety
    1. Ovens should be available in a separate area away from working artists, placed outside or in a separate room with excellent ventilation.
    2. If accidental overbaking or burning of polymer clay happens, turn off, unplug, open windows and walk away. DO NOT open oven door to let out fumes. Let it cool until you can handle it with bare hands.
    3. Convection ovens have a fan circulating the air for even heat in baking. NO NOT open oven door while a convection oven is in operation or you will get a blast of fumy air
    4. A separate selfcontained airtight roasting pan or closed foil tent to contain polymer clay vapors and fumes is an option for a homeoven that is also used for food preparation.
    5. Safety equipment: Oven mitts, oven timer, fire extinguisher
  6. Maintenance - Convection ovens with heavy use accumulate an oily residue on the oven walls and glass door. This needs to be periodically wiped out using paper towels along or with a lightweight glass cleaner. (Windex, simplegreen, etc.)

  7. When in doubt ASK.
Clay Conditioning - Margaret Regan

It is essential to condition all polymer clays. Conditioning increases clay strength and improves handling properties. It is your first opportunity to tune your clays; to effect color consistency and plaqueing.

The Basics - use a non-porous work surface. Peel the wrapper back and cut off the desired amount. Don’t cut through the cellophane, little bits can get into your clay.

Manipulate the clay, rolling into a coil, folding and twisting and repeating until the clay moves reliably in your hands. Brands vary in working properties. Also, polymer clay has a shelf life. An old batch of clay or clay that has been stored in a warm spot may be very difficult to work. If the clay is too still to roll into a coil, it can be warmed in your hands or tucked under a hot water bottle for five minutes.

A food processor may also be used, depending on your clay brand. If you are using a stiff clay like FIMO, a trip to the food processor is helpful Whirl small chunks of clay until the bits are warm to the touch--about 1 minute. Look for a cottage cheese curd consistency. It is possible to overdo this warming process. Some clays are very sensitive to food processor friction heat. The warmth of friction will start to set these clays.

Controlling consistency:

To soften stiff clays, add mineral oil or diluent (if using a food processor) or mix with a softer clay, like transparent or florescent, or a softer brand or a block of the clay you’ve chosen that is fresher. To harden soft clays, leach plasticizor out by placing flat sheets of clay on white paper (no ink against the clay, please, otherwise the ink will transfer to your clay). The oily plasticizor will soak into the paper. If you want to remove a lot of plasticizor, put weight on the paper/clay stack and change the papers as they become saturated. The surface touching the paper will “dry” and stiffen. It is necessary to reblend the clay to make it uniform.

If you intend to use caneing techniques in polymer clay, uniformity in clay consistency is critical. A pasta machine is a good tool for conditioning clay. Set the rollers for the widest space. A stiff clay will need to be flattened with a rolling pin to about a 1/8” thickness. Softer clays can be used with minimal flattening. Run the clay through the rollers, set the rollers to a thinner number and roll again. The clay sheet can be folded and sent through at a double thickness. If you want to minimize the bubbles, always have the fold positioned to go through the roller first. Knowing the properties of your clay brand(s) will help you condition appropriately.

Polymer is storage sensitive, and an old batch, or clays stored in a sunny spot, may be very difficult to condition. You can “hold” your unconditioned clays at the state they are in by freezing.

It is essential to condition FIMO, Premo, Sculpey and Cernit. A rule of thumb--by the time a color is completely mixed, the clay is conditioned. If you are using a package color, you won’t have a guide like your mixing color to track. Spend about 10 minutes per block of clay if mixing by hand, or about 20 runs through the pasta machine.

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