Coourser kiln wash?

[Travar]

Through the BB discussion about Evenheat's GTS2541 lid warping problems, Glass Glow kilns were mentioned. I looked them up on the web which led to my asking them some questions. I asked about their kiln shelf quality since I have had a lot of problems with bubbles from the shelf that came with my Evenheat GTS23. Their response to this question is as follows: "Use shelf primer that is a courser one. Ours is 325 mesh allowing for bubble escape at prefire of 350 for 10 minutes and firing at 300 degrees an hour from 1,000 to target 1500 for 10 minutes. the shelf are poured they are good but not perfect."

This could be the answer for many of us who have this same kiln shelf bubbles-in-the-glass problem. Question: Does anyone know where to buy this courser shelf primer? I don't see it offered on their web site. Thanks.

[Barbara Muth]

Or you could buy one of the awesome kiln shelves Bullseye sells.

Barbara

[Travar]

Barbara, I have thought of that but the Bullseye shelf won't fit in my kiln without alteration or something. Thanks for the reply.

[Brock]

Through the BB discussion about Evenheat's GTS2541 lid warping problems, Glass Glow kilns were mentioned. I looked them up on the web which led to my asking them some questions. I asked about their kiln shelf quality since I have had a lot of problems with bubbles from the shelf that came with my Evenheat GTS23. Their response to this question is as follows: "Use shelf primer that is a courser one. Ours is 325 mesh allowing for bubble escape at prefire of 350 for 10 minutes and firing at 300 degrees an hour from 1,000 to target 1500 for 10 minutes. the shelf are poured they are good but not perfect."

This could be the answer for many of us who have this same kiln shelf bubbles-in-the-glass problem. Question: Does anyone know where to buy this courser shelf primer? I don't see it offered on their web site. Thanks.

I can't agree with that. Over the years I have tried many kiln washes, and have found the coarser ones to be far more problematic. The bubbles that erupt through the glass, that are trapped between the bottom layer of glass and the shelf, can be eliminated by your firing schedule. A rapid rise to top temp. is usually the cause for these bubbles. A weak point is where they will appear. A weak point is where elements of your design meet, ANY gap there can be the locus of these bubbles. I do all my firing on kiln washed shelves, and haven't had a bubble like that in years. Brock

[Randy W]

I agree with Barbara, the shelf I got from Bullseye is excellent.

The shelves cut fairly easy, If you don't have a tile saw you could put a masonary blade in a skill saw and trim your shelf. Don't forget a respirator. Very dusty.

Randy

[Barbara Muth]

Someone I know recently bought a BE shelf and had it cut into an Octagon to fit a kiln with the same dimensions as yours. A round shelf is probably what you have. You can cut an octagon from the square shelves BE is selling and make it fit. Eventually they will (I hope) be selling round shelves as well!

Barbara

[Bert Weiss]

John Groth in Hillsboro Oregon can cut any kind of kiln shelf in to any shape (say jigsaw puzzle LOL) with his water jet. Because he can get the shelf directly at Bullseye you would only have to ship once.

The deal with the Bullseye shelves is that they are flat. Look at yours with a straight edge and notice the dips.

I posted last week about a source for coarse alumina. Kiln wash is 50% - 80% alumina and 20% - 50% kaolin. Kaolin is available at any pottery supplier. The more alumina in the mix, the harder it is to remove. Bullseye kiln wash is 50/50 and uses exceptionally fine alumina.

My personal mix is 80% alumina/20% kaolin. I can wipe it off with a paper towel. Which I do after every firing above 1400ºF. For slumping molds, I use 50/50 and leave it on.

Percentages are by weight.