Ferguson’s White Crackle Raku Glaze Recipe

Ferguson’s White Crackle
Raku
Glaze Material
Percentage
Gerstley Borate 65%
Nepheline Syenite 15
Tennessee Ball Clay 5
Tin Oxide 10
silica 5
100%
Comments
  • I’ve used Gerstley Borate 60%,Nepheline Syenite 40% for years. My cracking isn’t as defined as yours. I’m excited to see what happens when I tweak my glaze with silica and EPK clay. Thanks for sharing.

  • Hi, what can I use isntead of the Nepheline Syenite. I live in Colombia and I can not find it here. Thank you!

  • i agree with maria, because you use different names to certain materials in us, than in rest of the world, ixp frits with no, and epk… so please if possible use both.
    thanks

  • Melody,
    Rather then using cones to measure the heat work for a raku firing, most raku glaze is brought to maturity by sight. Peering into the kiln during the firing process (for this particular glaze) at or nearing 1800•f to see if the glaze has stopped bubbling and is smooth and glossy will tell you it has matured. Some raku glaze goes through a frothing or bubbling period prior to reaching its maturity point. I fired a pot last night using this glaze up to 1850•f, then turned off the burner, closed the kiln up and waited till the kiln cooled down to 1550•f. I pulled the pot using tongs and waved it around in the cool air for about 20-30 seconds the put in a can with wood shavings and straw, allowed it to flame up for about 15 seconds the sealed the container. I took it out after it cooled and scrubbed it clean and the glaze came out very smooth and glossy with a larger dark crackle pattern and a smaller less dominant crackle pattern within the dark pattern. I would say pretty much like the picture given here with this recipe. I am very happy and will be using this glaze often. By the way, a nice white clay makes a perfect background for this white crackle but I am sure it will work nicely on darker clays too. I am looking forward to adding color to this glaze as well.
    Keep practicing! Paul

  • I have tried that whit crackle on max white and Sylvia’s raku clay and it doesn’t crackle or so lightly I made the recipe exactly and I still do not get those good black crackles I need some help thanks

  • To Marie- Therese Latortue,
    I have had good success with this glaze and have added mason stains (8-15%) as well as copper carb and cobalt carb for some great color. Try allowing the pot to cool out of the kiln (20-30 seconds) before putting it in a reduction container. Make sure that you get a real good flame going in the container before sealing shut. After a minute, burp the container and allow it to flame up again then seal it tight again. Newspaper, very dry leaves or pine needles works good for me. I hope this helps. Read my long post to Melody too. More info there.
    -Paul

  • A groggy “open” white stoneware seems to be creating the best background for these contrasting crackle patterns. Of course you can apply a white terra sig. to any clay that can withstand the thermal shock of the Raku process. Just because your pot doesn’t come out the way YOU expect it doesn’t mean that others will think its a dud. Expect the unexpected when firing Raku! Have fun!

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