You need to bake your project hot enough and long enough to ensure a complete cure. In most cases, you can bake polymer clay at 275F for about 30 minutes per 1/4 inch of thickness. That said, always check your package instructions for the most accurate information – since all brands are different.
You can try a few different methods if you're looking for a way to harden your modeling clay without baking it. One popular method is to use a blast of air from a can of compressed air. Another is to let the clay dry out slowly and naturally over time. You can also use a hairdryer on the lowest setting.
If your clay isn't hardening after 12 hours or so, try increasing the temperature by blowing the clay with a hair dryer, or placing it in the oven on the lowest temperature for 1-2 hours.
All brands of polymer clay will instruct you to bake the clay in order to cure your piece. Polymer clay does not harden or dry when left exposed to the air, so you will not be able to use or keep your piece permanently if it is not properly cured using an oven.
Non-drying polymer clay cannot dry out from air exposure and remains workable until it's cured in the oven. Once baked, polymer clay will dry and permanently cure to a hardened, fixed state.
Place pots on shelves so that air can freely circulate around each piece. Do not force dry pottery. Using heaters or hot air blowers like hair dryers can cause severe cracking, especially when the clay is already leather-hard or drier. Slow, even drying is best.
The general time it takes for air-dry clay to dry is around 24 hours to 72 hours. However, if you have larger clay projects, you might have to wait a little longer for the piece to dry properly. It is best to leave the clay dry naturally, rather than to speed things up.
If you take your clay out of the oven and find it's still soft, it could be one of two reasons: the temperature was too low, or it wasn't baked long enough. Test the accuracy of your oven with an independent thermometer and give the piece another baking cycle.
Air-dry clays were developed for artists who desire the integrity of clay but do not have easy access to a kiln. Most air-dry clays are mineral based and have properties comparable to those of traditional clays. They harden within a few days and do not need to be fired to create a permanent form.
Can You Paint Air-Dry Clay Before it Dries? No, you need to wait for the clay to fully dry before you begin painting. By painting the clay while it is still wet, you run the risk of altering the clay item and causing cracks. However, you can color or dye the clay with paint before it dries by kneading in the paint.
Clay hardens when fired in a kiln because of the process of vitrification. Vitrification is a process of heating clay to a certain temperature, usually about 1800°F. At this temperature, the clay molecules begin to rearrange and bond together and form a solid mass.
It generally takes 24 to 72 hours for air-dry clay to dry. Larger projects may take up to a week to dry out. You can expect air-dry clay to begin hardening as soon as it gets exposed to air, so any leftover clay should be stored in an air-tight container to keep in moisture.
When firing without a kiln, it may help to pre-dry you clay pieces in a kitchen oven set to 190 degrees F. With a kitchen oven, the pots are dried by "baking" below the boiling temperature of water for several hours.
Silicone Clay - Never dries out and can be permanently set by heating.
Depending on environmental conditions, it can take 24-48 hours to dry. If part of your project is against your work surface the entire time, moisture is trapped underneath and it will take even longer to dry. Be sure to flip your project over to ensure all parts get exposure to air and dry thoroughly.
Cracking is normal in air dry clays: it's caused by shrinkage because of the loss of the water inside the clay body. Cracking in air dry clay is typically caused by sculpting over an armature or using a lot of water, either to mix the clay or to help it adhere onto a previous layer.
Step1: Preheat your oven to 200 degrees Fahrenheit and bake the clay for about 15 minutes. This will help to draw out the moisture from the clay so that it dries faster. Step 2: Another option is to put the clay in a dehydrator or desiccant chamber. This will help absorb the clay's moisture and speed up drying.
Polymer, or non-harden, clay is a clay made from polymer polyvinyl chloride, or PVC. It will not harden when exposed to air, so it is ideal for people who are learning to mold or enjoy molding and remolding with the same materials. If you create a piece you want preserved, you can harden the polymer through baking.
Bake for 15 minutes per quarter inch of thickness. For example, a piece of 1/2" thickness should be cured for 30 minutes. To test the curing, try pressing the tip of your fingernail into the bottom of your piece after it has cooled; it will leave a mark but will not actually enter the clay.
Can Air-Dry Clay Be Frozen? The answer is yes; This is because air-dry clay has a similar makeup to other types of clay. While it is true that freezing leftover air dry clay may cause it to become brittle, it will not significantly affect the overall structure or quality of the clay.
Avoid leaving it in the sun, using a hairdryer or putting it in the oven as this can cause cracks when the project hasn't dried evenly.
Using Too Much Water
Water plays a major role when it comes to air dry clay. Not only is it used to bring dry clay back to life but it is also used to join clay together. On the flip side, if you used too much water you can actually make your clay unusable because it will become very sticky.
They are water-based and will dry out when left out in the open air. Once dry, they cannot be re-hydrated and used any more. Some dried air dry clays will disintegrated if left soaking in water for a long time, but I would warn against trying this method to "revive" your clay.