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.
In order to dry properly, air dry clay projects should be exposed to air on all sides at the same time. This will help prevent warping and cracking. We recommend drying pieces on a screen or cookie rack, for example, where air flow is the same on all sides.
Air-dry clay usually takes 24-48 hours to dry completely.
However, it is best to check on the clay periodically to be sure. If you're looking for a quicker option, you may consider modeling clay that will dry in less than 24h. Baking air dry clay can cause it to warp or crack.
Depending on the thickness of your project, air dry clay will dry to earthenware hardness in around 24 hours. If you want to work on your piece in multiple sessions, wrap it in a damp tea towel and then cover it with cling wrap to make it air tight. This should keep it workable for around 4 days.
They harden within a few days and do not need to be fired to create a permanent form. Air-dry clay vessels and sculptures are more fragile than traditional kiln-fired ceramics, but they can be sealed and strengthened with shellac and paint.
If you are in need of a versatile air dry clay that is non-toxic and suitable for all ages, the DAS Air-Hardening clay is crack-resistant, dries in 24 hours, and comes in white and terra cotta. For serious art projects, the Creative Paperclay clay can be painted or sanded making it suitable for sculptures and molds.
Even when dry, the air-dry clay remains prone to dents and scratches. To strengthen its surface, coat it with a few layers of primer. It works wonders forming a smooth and sturdy exterior. Unfortunately, most good-quality primers come in grey color, so it can be harder to paint the surface later.
Air dry clay can get moldy, either when it is part of an open pack or as part of a sculpture that is exposed to water when it hasn't been fully dried and sealed. Where mold is clearly visible, skin contact should be avoided and the mold either cut out or treated with a water/bleach mixture.
Degradation over time
They can have a tendency to crack during hardening if certain methods aren't followed, which I'll cover below. They usually contain a lot of water. As the water evaporates, the clay loses mass and shrinks, and it does that from the outside in.
Adding too much water to your DIY air dry clay can sometimes result in a crack. Do your best to keep the clay moist as you work, but not overly saturated with water. If you have too much water, I recommend setting your clay out to dry for an hour or two before continuing on.
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.
In a bowl, mix a ratio of 80% PVA glue to 20% water to create a creamy consistency, and then coat your fully dried clay piece, and allow the sealer mixture to dry. Once you have applied your PVA glue mixture or acrylic medium, you can then apply 3 coats of acrylic paint to seal your work.
It will adhere to any core material such as wire mesh, rigid wrap, paper, glass, plastic, wood or Styrofoam. Acrylic or oil paints can be kneaded into tint this clay creating original colors.
You can make anything you want with air-dry clay but any bowls, plates or mugs made with air dry clay are for decorative purposes only and are not food-safe, as it is a type of clay designed to be left unsealed and is not watertight or food safe.
You can drill holes in air dry clay, but I find that making the holes first is way easier. - Keep in mind how the piece is to be worn.
What is the best sealant for air dry clay? The best option to provide a water-resistant, durable seal on air dry clay objects is to use a polyurethane or acrylic sealer. These provide a durable, water-resistant finish to protect the air dry clay and prevent it from yellowing.
Self-hardening clays (also known as air-dried, air-hardening or non-firing) should not be fired in a kiln, and are generally ceramic clay body formulas with a natural additive, such as cornstarch, to make them harden.
Use varnish, acrylic sealer, or liquid epoxy resin to seal your clay if you want it to be water-resistant. Just because you sealed your air-dry clay does not mean that it can withstand long direct contact with water. It only means that it will resist a few drops of water.
There are many options for pre-coloring air dry clay, so feel free to experiment! Acrylic, tempera, or poster paints will give you a solid bright color. Oil paints will also work for basic coloring, but they're harder to clean. If you want a deep, vivid color, try artists' quality acrylic or oil paint.
Believe it or not, it is possible to sand air dry clay. Once your clay has dried completely and hardened, you can use a piece of sand paper to smooth out any sharp edges. You may want to start with a small grit to refine any rough edges before gradually increasing the grit to a finer level to polish the clay.
Water can be added to Air-Dry Clay to soften or join pieces. If too much water is added and clay is very soft, allow excess to evaporate before molding pieces; otherwise, cracking may result.
Bake It! The fastest and most effective way to dry Creative Paperclay (and it can be applied to similar clays, such as La Doll), is actually to bake it in a standard oven.