Using Crystal Glazes

Crystal Art Crystal Pots Crystal Images

The crystals formed in these glazes depend on the chemical composition of the glaze and the style of firing. Firstly the glaze must contain the catalyst to start the crystal growth. This is normally zinc. Then during the firing the glass being formed must become relatively soft to allow the growth of the petals within a reasonable time. The consequence for the potter is that the glazes are very mobile, tending to slip off the pot all over the kiln. They must be fired in oxidation to hold the zinc and cooled very slowly (holding the kiln above 1100 degrees C for an extra 3 hours). Once again the results are anything but predictable. The crystals are thought to be zinc silicate (willemite).

Large Slab pot by Ric

Slab 53cm wide, crystal landscape

 Crystal landscape

21cm shallow bowl
Crystal extruded vase
  1. Extruded vase 52cm high
 Crystalline glaze before firing

Crystal glaze before firing in the kiln, "landscape design" (I hope)

 
Using glaze movement by Judy

46cm high

 Reduced Copper Red and Oxidised Crystalline Glaze by Ric

Reduced Copper Red with Oxidised White Zinc Crystalline Glaze

 
Extruded teapot

48cm high

 Crystal load ready for firing

After applying the glaze, the pots show little relationship to the finished look. They are soft, matt and easily damaged. Firing to 1300 degrees centigrade will fix all.
 Crystal glaze used to create Landscape image

28cm*32cm Rectangle "The Storm"

Showing off crystals to advantage by Ric

36cm diameter
Seger Cone 10 before firingSeger Cone 10 after firing

This is a cone. It measures the effect of the kiln heat on the pots, left is before firing, right is after firing, it is visible through a spy hole in the kiln during the firing.

 Showing off crystals to advantage by Ric

30cm diameter

 
Dancer image by Judy

Ghost Dancers 22cm*13cm

  

 

Crystal glazes as a landscape by Ric

30cm long

Large bowl

Large flattish bowl with "shore line" design, 48cm diameter

 
Tiny bowl
 Crystalline cooling rings

See how the two stage cooling created the "flange" on the crystal. Check out other pots for this characteristic.
Using bowl shape to control glaze flow

Bowl 34cm diam

Taking advantage of the crystalline glaze flow

Slab pot 95cm high
 Subtle white crystals over white background by Ric

Vase 34cm diam

Taking advantage of the pot shape Balloon, 15cm high

Revised: 03/07/07

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