• Gerstley Borate 65
• Nepheline Syenite 20
• EPK (Kaolin) 5
• Flint (Silica) 10
• Copper Carbonate 10

You want to apply this glaze fairly thick and it needs to be fired a little hotter than some Raku glazes – somewhere around 1850F-1900F. The piece should be pulled from the kiln and then held in the air for about 15 seconds and then placed in a reduction chamber with combustibles. If it is reduced too much it will be mainly copper. If it is lightly reduced it will mainly be dark green with crackle. If it is reduced “just right” you will get green crackle with copper flashing.

Lidded, Double-walled pot with Gary’s Green Crackle by Gary R. Ferguson