Comment

Comment by Norm Stuart on June 23, 2013 at 1:50pm

The best kiln wash I've used is from Ceramics Art Daily. It's more convenient than 1/4" of alumina hydrate powder on the shelf, but we currently use both.

Kiln wash containing Silica will melt if too much liquid glaze flows onto it.

http://ceramicartsdaily.org/firing-techniques/soda-firing/the-many-...

50% Alumina Hydrate

35% Calcined EPK Kaolin (sold as Glomax, or calcine your own in your kiln)

14% EPK Kaolin

 1% Feldspar

 1% Darvan 811 (deflocculates wash for self-leveling attributes)

As the article mentions, you need at least 10% to 15% kaolin to suspend the kiln wash. Glomax does not suspend but it also does not shrink. The 1% to 2% feldspar provides just enough melting to keep the kiln wash on the shelf, rather than powdering off.

The only space-age ingredient I can imagine Lee could add to kiln wash would be Boron Nitride, unless you consider Glomax to be a space-age ingredient.

Boron Nitride powder costs about $65 a pound and is also available in a spray can (used for glass molds).  Boron nitride, like alumina hydrate, makes an excellent dry lubricant to allow heavy pieces to expand and contract in the kiln. The alternative is to use one fixed point and two ceramic pie balls (normally used to weigh down pie dough) to support a large piece in the kiln.

I've never compared boron nitride to alumina hydrate as alumina hydrate costs less than $2 a pound, but if I bought some it might surprise me. Oddly it's also used in most lipsticks and other cosmetics due to it ability to lubricate.

http://sandblastingabrasives.com/Bullet-Lube-Gun-Barrel-Bore-and-Bu...

http://www.amazon.com/Spray-Mold-Release-new-Nitride-Brands/dp/B00A...

http://digitalfire.com/4sight/material/boron_nitride_133.html

Comment by Norm Stuart on June 23, 2013 at 1:25pm

Add silica to stiffen without changing the finished look of a glaze, or a combination of silica with kaolin to maintain the ratio between silica and alumina.

I've found 20% added silica can make most low-fire ^06 glazes into successful ^6 glazes. Stiffening a runny ^6 glaze may take as little as 5% added silica.

If the glaze is made with frit or feldspars you can also reduce these somewhat to stiffen the glaze, but this will often change the finished look.

Comment by juli long on June 23, 2013 at 11:36am

Norm, I use "Lee's super incredible kiln wash" and it is what it states. I just wish I knew what to add or take away from the glaze recipe to stiffen it up.  Im not that glaze savvy!

Comment by Norm Stuart on June 23, 2013 at 10:01am

Those extra feet are sadly a common occurrence at our studio.

As a result we've resorted to covering our kiln shelves with 1/4" of Alumina Hydrate "sand" on top of each kiln-washed shelf.  That way the extra glaze sticks to nothing other than the ware it came from. For us it's an ideal solution.

Comment by juli long on June 23, 2013 at 8:14am

Ouch, I didnt want those two extra feet. cinco rojo cone 5 clay.