Techniques for Curing Polymer Clay

• Super Sculpey should be cured in a preheated 275° F (130° C) oven for 15 minutes per quarter inch of thickness. DO NOT MICROWAVE. For example, a piece of ½" thickness would be cured for 30 minutes. The layering method is recommended for lager pieces of construction.

• Premo! Sculpey should be cured at 275° F (130° C) in a preheated oven for 30 minutes per quarter inch of thickness. DO NOT MICROWAVE. Once cured, the colors intensify and deepen.

• Sculpey III should be cured in a preheated 275° F (130° C) oven for 15 minutes per quarter inch of thickness. DO NOT MICROWAVE. If you're unsure whether your piece is adequately cured, try pressing the tip of a fingernail into the bottom of your piece after it has cooled; it will leave a mark but will not actually enter the clay.

• Any home oven is suitable for hardening FIMO. Preheat the oven at 110°C/230°F. Place the FIMO model on an aluminum sheet, and plate or glass sheet and put it in the oven. Depending on teh size of the model and the thickness of the walls, the hardening process takes approx. 20-30 minutes. FIMO reaches maximum hardness when completely cool.

• Cured at 275° F (130° C), this clay can be used in a household oven. For every 1/4 inch of thickness, it should be cured for 10 minutes.

• Kato Polyclay, oven hardening polymer clay, bakes at 300° F (150° C). However, it can also be cured at 275° F (135° C) with good results and has been approved to cure at 350° F by our toxicologist, however caution should be taken when curing at that temperature, time should be limited to 10 minutes as you will run the risk of discoloration. You should never exceed 365° F. In prior laboratory testing, it has been determined that tensile strength increases
  

Eberhard Faber Fimo Classic Polymer Clay

Super Sculpey

Premo! Sculpey Artists' Polymer Clay

Ramp baking is a technique for gradually baking polymer clay to achieve a hard but minimally darkened result.

Starting at a low temperature of around 175-200° F bake for 30 minutes, increase the temperature by 15-30° and bake for 20 minutes, continue increasing the temperature by 15-30° and baking for 20 minutes after each increase until the temperature reaches the manufacturer recommended temperature. Bake at the recommended temperature for 30 minutes. Allow the piece to cool completely in the oven before moving.

This method requires careful monitoring to make sure the piece doesn't start darkening excessively. Some oven temperatures can spike significantly, always use a separate oven thermometer to monitor temperature.

Under baking is a technique used to try and prevent the darkening that some clays experience. It involves baking under the recommended temperature, usually at around 200° F, for an extended period of time often 1-3 hours depending on the thickness of the clay.

The main risk of under baking is a polymer clay piece which is weak or degrades over time due to the clay not being fully cured.

Over baking is a form of ramp baking used by some sculptors like Casey Love usually with super sculpey to get a very hard result with no cracks. Because the technique causes significant darkening of the clay it's used for sculptures that are to be molded for casting or painted.

Start at 225 and leave the sculpt for an hour, raise the temp to 250 for another hour, raise the temp again to 275 for 2- 3 hours or until the Super Sculpey has truned a dark caramel or even as dark as a redish brown brick color. Shut off the oven and leave the sculpt to completely cool down before removing the sculpture. If you are baking a rather thick sculpture use the same method above but raise the temperature slower and in smaller incraments.

The main risk of over baking is potential emission of small amounts of hydrochloric acid gas which can irritate the eyes, throat, and lungs. Burning can also occur.

Heat guns can be used to cure small polymer clay pieces or to partially cure a sculpture to harden an area to protect it from damage while working on the rest of the sculpture. Heat guns are not suitable for completely curing large polymer clay pieces.

To use a heat gun turn it on either a low setting or if it has a dial set it as close to 275 degrees as you can. Aim the heat gun at the piece and keep constantly moving to prevent burning. Watch for the surface to go dull and darken slightly to determine if the clay has cured.

Heat guns take practice to effectively be used for polymer clay and they are the most unreliable of all curing techniques. Burning, bubbling, and blistering of the clay can occur if care isn't taken. Practice on scrap clay first to get the technique down. Always use a heat gun in a well ventilated area.

Gently boil small polymer clay pieces such as beads either in the microwave or on a stove top for at least 15 minutes and up to 1 hour. You must completely cover the clay with water or you risk over heating and other problems.

There is some debate about whether boiling completely cures polymer clay especially for items larger than beads.

• To reduce temperature spikes in toaster ovens lay small ceramic tiles or pieces of broken ceramic such as from a terracotta flower pot in the bottom of the oven. The pieces of ceramic absorb and then radiate heat helping to keep the temperature even.


• If you have to use a kitchen oven for curign your clay, encase it using a covered baking dish or roasting bag to reduce any build up of residue on your oven walls.


• Lay polymer clay pieces on polyfil batting to cushion pieces so the bottom does not get flattened shiny spots.


• For sculptures with areas of thin and thick clay protect the thinner areas from darkening more than the thick areas by covering them with aluminum foil.

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