Cratered
Cratering is a decorative effect that manifests itself as small depressions or holes in the surface of the glaze, resembling craters on the moon. This phenomenon occurs mainly during the firing process, when gases trapped within the glaze or clay try to escape as the pieces reach high temperatures. If these gases cannot be released efficiently before the glaze solidifies, bubbles are formed which, upon cooling, leave visible crater marks. Glaze density, firing temperature and chemical composition play crucial roles in the formation of these craters.
Although cratering can be considered a defect in contexts where a smooth, uniform surface is sought, it can also be deliberately employed to add texture and character to pieces. In addition, some glazes are specifically formulated to promote cratering by incorporating elements that promote the generation of bubbles during firing.
Cratering can also influence the functionality of the part, as it can affect impermeability and wear resistance. In utilitarian applications, excessive cratering can compromise the structural integrity of the ceramic, making it less suitable for holding liquids. On the other hand, in decorative pieces, craters can add a tactile dimension that enriches the sensory experience of the object.Interesting Fact
In the raku technique, the extreme thermal shock to which ceramic pieces are subjected when removed from the kiln and immersed in combustible materials causes the controlled formation of craters. This method not only creates dramatic visual effects, but also symbolizes impermanence and transformation, concepts deeply rooted in the Japanese philosophy of wabi-sabi.Helpful Tip
If you want to avoid cratering of your functional parts, make sure your glaze is well sieved to remove any particles that may trap air. Apply thin, even layers of glaze to reduce the risk of bubbling during firing. Also, carefully control the firing temperature and kiln atmosphere to facilitate the release of gases before the glaze solidifies completely.
