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:
Oven Etiquette in a Group or Class Setting - Pier Voulkos
- 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
- 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
- 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.
Clay Conditioning - Margaret Regan
- 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.
- 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.
- Never open an operating oven to just throw your piece in. Even if there seems to be plenty of room.
- 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.
- slow cooling may be important and opening the oven door may be a
- Only remove another persons work from the oven with their permission
unless it is totally cool and can be handled without oven mitts
- To preheat or not to preheat????
- Some clays and techniques benefit from a cold oven start. Others, a pre-heated oven is fine or necessary.
- Some ovens can handle a cold oven start, some a preheat is necessary.
- 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.
- 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.
- Bumping a toaster oven is NOT recommended
- Ovens should be available in a separate area away from working artists,
placed outside or in a separate room with excellent ventilation.
- 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.
- 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
- 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.
- Safety equipment: Oven mitts, oven timer, fire extinguisher
- 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,
- When in doubt ASK.
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.
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
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
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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