What Are Crystalline Glazed Ceramics?
Quick answer: Crystalline glazed ceramics are pottery finished with a special glaze that grows visible crystals on the surface during firing. The crystals form from zinc and silica as the kiln slowly cools, and coloring oxides such as cobalt and copper give each piece its hue. Because the process is delicate and unpredictable, no two pieces are ever exactly alike.
What the glaze is made of
When we talk about crystalline ceramics, we mean the glaze rather than the clay. The glaze contains zinc oxide and silica, which combine so that macro-crystals grow around tiny seed crystals of zinc oxide. Other additions such as titanium and lithium encourage growth, while coloring oxides like cobalt, nickel, copper, iron and manganese react in different ways. A mix of cobalt and manganese, for example, turns the crystals blue.
How the crystals grow
The piece is coated with a thick 4 to 5 mm layer of glaze at the top, thinner at the base, because the glaze runs as it melts. It is fired at around 1,280°C until the molten glaze forms a liquid matrix, then the kiln is cooled to roughly 1,050 to 1,150°C, the range at which crystals grow over about 3 to 5 hours. The cooling temperature decides the shape: lower temperatures give round crystals, higher ones produce spikes and axe-head forms, and a fluctuating kiln can create halo rings on a single piece.
Why every piece is unique
Because the glaze runs, each piece needs its own catcher ring and plate to protect the kiln, which is later ground smooth by hand. The crystals set their final shape and color as they cool and never change again. Some pieces are then acid-etched for 24 hours to make the crystals stand out further. The result is that every crystalline piece is genuinely one of a kind and impossible to replicate exactly.
Frequently asked questions
What makes crystalline glaze form crystals?
The glaze contains zinc oxide and silica. As the kiln slowly cools after firing, these combine and grow into visible crystals around tiny seed crystals of zinc oxide. The cooling temperature controls the size and shape of the crystals.
Why is each crystalline glazed urn unique?
The crystals grow naturally during a slow, fluctuating cooling process, so their size, shape, color and placement can never be exactly repeated. Each urn sets its final appearance as it cools and stays that way permanently.
What temperature are crystalline ceramics fired at?
They are fired at around 1,280°C until the glaze melts into a liquid matrix, then cooled to roughly 1,050 to 1,150°C, where the crystals grow over about 3 to 5 hours.
Are crystalline glazed urns suitable for ashes?
Yes. Crystalline glazed ceramic is fired at a high temperature, making it strong and suitable for indoor or outdoor display. You can browse our crystal urns and crystalline glazed range in adult, medium and pet sizes.
Leave a comment
This site is protected by hCaptcha and the hCaptcha Privacy Policy and Terms of Service apply.