Plainsman Super Kiln Wash

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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

Total:814.00

Notes

*This produces a super-refractory powder layer that stays in place and does not harden after many firings like common 50:50 kaolin:silica kiln wash. This also does not not shrink and crack nearly as much.

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).

Strangely, calcined, rather than raw kaolin, imparts multiple advantages:
-Better coverage.
-It does not shrink and crack.
-Much less water is needed.
-Normally the raw kaolin suspends the slurry, makes it brushable (just barely) and hardens it on drying. But CMC gum hardens even better and makes it work like paint (suitable even for use with a paint roller).
-Dries far slower. Even on absorbent alumina shelves an even and thin layer can be applied effectively.

This recipe produces enough to fill a pint jar. The Laguna gum solution has 6.7g CMC Gum per 100g - if you do not have it then add 7.5g powdered CMC and 313 total water. It is a little difficult to get all the powder into this amount of water, however a thin paintable slurry is produced. While blender mixing would seem best, your mixer may not have enough power (because this type of slurry is subject to a phenomenon known as "shear thickening". A propeller mixer should be fine for the gum solution version, but for powdered gum, mixing, aging for a few days and mixing again might be 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).

The use of calcined kaolin brings issues with the slurry settling in a hard layer (flocculating with Epsom salts and calcium chloride was tried, but that is not realistic with a slurry having such a high specific gravity). The hard material can be stirred back with effort and it remains usable for a few days (in all, we feel the benefits outweigh these issues). It is possible settling could be prevented by using a raw:calcine mix of kaolin (but other properties would be compromised). If you find a way to keep it from settling please let us know.

The Dettol was needed to alleviate the rotten smell (bacteria seems to like this recipe!).

Pictures

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="sdBj9ycf" date="2024-12-10" codenum="L4001"> <recipelines> <recipeline material="Zircopax" amount="400.000" tolerance=""/> <recipeline material="Calcined Kaolin" amount="100.000" tolerance=""/> <recipeline material="Laguna Gum Solution" amount="113.000" added="true"/> <recipeline material="Water" amount="200.000" added="true"/> <recipeline material="Dettol" amount="1.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2017-08-03, Modified: 2024-12-10 19:47:11