WarmGlass.com

I recently fired a piece that incorprated some BE thin vanilla glass. As it was a 2nd firing and I was bringing it up to 1425 slowly, I used Spray A to guard against devit. Big mistake! The thin vanilla turned a dark mustard color, while all other glass was unaffected. Anyone know why? Do other glasses respond similarly?
I could have used it in a painterly fashion, had I known what to expect. I thought about adding yet another layer of thin vanilla and then refire to mellow the color (the mustard would show through, but not as strong), but wondered if the spray A would again affect the new layer since it would be in contact with the layer below where it was previously used.
Any thoughts?
Thanks, Sheila

You can just sandblast off the top layer. The lead in the Spray A reacts with the Sulfur in the FV.

Amy

Spray A contains lead which reacts with the French vanilla. Use borax for devit.

How you view the reaction makes it a feature or a flaw.

Ron

Ron Coleman wrote:Spray A contains lead which reacts with the French vanilla. Use borax for devit.

How you view the reaction makes it a feature or a flaw.

To elaborate on Ron's comment: French vanilla (BE 0137) contains sulphur. Spray A contains lead. When the two are mixed, you get lead sulphide and the mustardy color. This is a predictable reaction, so you can use it to achieve a particular effect if you wish.

Bullseye's amber glasses (1137 and 1437 -- that "37" is a clue!) will react with lead similarly.

As Ron says, if you want to avoid the effect, use a non-lead bearing spray, such as borax/water or SuperSpray.

I often use Spray A as anti-devit and it always leaves milky signes looking like something inside the glass, not like grease. Here we do not have something else to buy at the glass stores. Now I bought the borax powder at the store for jewellery needs. How do you use it? Should I mix it with the purified water or another medium? And how to apply - for each firing or just once?
Thanks.
Anna.

http://www.warmglass.com/making_your_own.htm#DEVIT

I add a couple drops of dish soap as a surfactant to give it some surface tension like a sticker spreader. I also apply it every time I take the piece to full fuse temps. It matures at full fuse temps and doesn't work well at any processing temps that are lower than that (in my experience).

Thank you, Cynthia. Do you even get devit at slumping temp? How to avoid it?