Share from Insight-live.com (Lab Documentation and Calculation System) by Digitalfire. https://digitalfire.com
Stop using cheap kiln wash, get something good. You will never go back to anything else. This uses the Cadillac of refractory materials and binds it down with gum.
Plainsman Super Kiln Wash
|*Laguna Gum Solution||113.000||GM||22.60%|
*This produces a super-refractory powder layer that stays in place and does not harden excessively after many firings, does not chip or cake, that does not shrink and crack. Because it contains gum it paints on very well, staying wet long enough to level and even out with a brush. Also useful as a refractory ceramic coating.
Zircopax is among the most refractory materials in ceramics, so it was chosen to form the bulk of the dry mix (calcined alumina could also be used). Calcined, rather than raw kaolin, was employed to help densify and stabilize the coverage (by its flat particle shape).
Laguna gum solution was added to harden the dry layer and slow down the drying (drying too fast is a major problem with most kiln washes). The slurry produced paints evenly onto even absorbent alumina shelves, especially with a small paint roller.
This produces enough to fill a pint jar. The Laguna gum solution has 6.6g CMC Gum per 100g. It is a little difficult to mix in the final amount of powder yet a thin paintable slurry is produced (a good propeller mixer is needed). Specific gravity: 1.87. Approximate retail cost: $7.50. One pint coverage (single-coat): Nine 12 x 24 gas kiln shelves (about 18 square feet).
We continue to have issues with the slurry settling in a hard layer (epsom salts was used in initial testing but it did not prevent settling and the slurry developed a rotten smell). Calcium chloride addition of approx. 2 grams worked for a few days, but returned to hard-panning. However once the hard material is stirred back in it works normally, and the benefits outweigh this issue.
We also added 1 gram of Dettol to this mixture to alleviate rotten smell, and this has worked well over time (if you do not mind the Dettol smell).
L4001 Kiln wash (left) vs. typical kaolin:silica wash (right)
The new wash has been fired on and is adhering well, not shrinking or cracking and is not powdery. The layer is much thinner. The other side has been fired many times and the flakes stick to the foot rings of every piece fired in the kiln.
Super Kiln Wash
XML (to paste into Insight)
<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Plainsman Super Kiln Wash" id="115132" key="Q5tJPWpf" date="2021-12-19" codenum="L4001"> <recipelines> <recipeline material="Zircopax" amount="400.000" tolerance="" unitabbr="GM"/> <recipeline material="Calcined Kaolin" amount="100.000" tolerance="" unitabbr="GM"/> <recipeline material="Laguna Gum Solution" amount="113.000" unitabbr="GM" added="true"/> <recipeline material="Water" amount="200.000" unitabbr="GM" added="true"/> <recipeline material="Calcium Chloride" amount="2.000" unitabbr="GM" added="true"/> </recipelines> </recipe> </recipes>