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I have 3 separate background pieces that have been fully fused. I'm planning on adding elements on top that will be taken to just tack/fire polish (in my larger 24" sq. shelf kiln, that's about 1450; 1525 is almost full fuse but with a slight contour and 1600 is fully fused). I know these temps seem excessive, but they work.

I don't have any Spray A (it's on order). I've been using a borax solution, but haven't had alot of luck with it. There's slight devit in some areas. In particular, where black stripes meet french vanilla. It's kind of a scum really. There are areas on the fr.van. that have some devit as well.

When I'm ready to fire polish, will using Spray A remove all signs of this devit? If not, will I need to sandblast, refire with Spray A, then another firing for top pieces?

Though there's alot of info in the archives on Spray A, but I didn't find an answer to this.

Thanks ...Kelly

KAG wrote:I have 3 separate background pieces that have been fully fused. I'm planning on adding elements on top that will be taken to just tack/fire polish (in my larger 24" sq. shelf kiln, that's about 1450; 1525 is almost full fuse but with a slight contour and 1600 is fully fused). I know these temps seem excessive, but they work.

I don't have any Spray A (it's on order). I've been using a borax solution, but haven't had alot of luck with it. There's slight devit in some areas. In particular, where black stripes meet french vanilla. It's kind of a scum really. There are areas on the fr.van. that have some devit as well.

When I'm ready to fire polish, will using Spray A remove all signs of this devit? If not, will I need to sandblast, refire with Spray A, then another firing for top pieces?

Though there's alot of info in the archives on Spray A, but I didn't find an answer to this.

Thanks ...Kelly

Hi Kelly,

I don't use overglazes at all, but if I was trying to accomplish what you are describing I would:

-sandblast the background pieces
-add the new design elements
-refire to your tack fuse temp, but use a schedule that minimizes the amount of time above 1150F. (So, in your kiln, I might bring the glass slowly to 1000F, hold there for 20 min, and then heat up to 1450F at 800dph, hold for the shortest time you can and get your tack fuse, and then flash cool down to 1000F.) I have managed to avoid devit on devit-prone pieces with this type of schedule.

If there is a better solution consisting of sandblasting and spraying with Spray A, maybe somebody else can advise you about that.

Hope this helps.

Steve

I don't know if this will work for you but I have used acid etching instead of sandblasting to successfully remove devit on cabochons. I have not tried it on anything large though.

Hey there Kelly - Don't put Spray A on French Vanilla unless you want mustard yucky yellow. I learned that one the hard way. Its a reaction you want to avoid.

Jackie Beckman wrote:Don't put Spray A on French Vanilla unless you want mustard yucky yellow. I learned that one the hard way. Its a reaction you want to avoid.

Thanks Jackie - THAT'S GOOD INFO TO KNOW !

...Kelly

Jackie Beckman wrote:Hey there Kelly - Don't put Spray A on French Vanilla unless you want mustard yucky yellow. I learned that one the hard way. Its a reaction you want to avoid.

Hmnnnn, to me its a luscious aged parchment look.... But yeah it won't be french vanilla anymore.

Jackie, were you able to blast it off, or did the reaction go deep?

Barbara

I just got off the phone with BE and I believe I have "stumped the staff". They're going to do some brainstorming, but it may be next week before I get an answer. BE doesn't sell nor do they use Spray A.

Things I've done -

Wash glass with solution of ammonia/H20 (25/75), rinse thoroughly, dry. OK - I probably need to stop doing this, but it's hard to believe that this may be causing my random crystalization/devit problem.

My kiln gets through the 1300 deg range in about 5-7 minutes on the way up. It can take 15 minutes or more going back down. I flash vented these 3 pieces thru this range.

I have used Borax solution in the past, but with limited results.

I've ordered both clear and lead free overglaze spray from CR Loo. Are all overglazes the same? In other words, would this be the same as Spray A?

I'm probably going to take Steve's suggestion -- sandblast surface, add elements on top, then refire to tack/fire polish.

Any thoughts on what may be causing my devit problem. Betchagonna say ammonia.

...Kelly

Kelly you are too smart for words. I'm betting on ammonia. Try using dishsoap and after rinsing if it isn't squeaky enough for you, some rubbing alcohol. Ammonia no, alcohol yes.

Also just FYI, I think it is the lead in the Spray A that causes that reaction.

In general I find that the best solution for devit is to sandblast.

Barbara

Barbara Muth wrote:

Jackie Beckman wrote:Hey there Kelly - Don't put Spray A on French Vanilla unless you want mustard yucky yellow. I learned that one the hard way. Its a reaction you want to avoid.

Hmnnnn, to me its a luscious aged parchment look.... But yeah it won't be french vanilla anymore.

Jackie, were you able to blast it off, or did the reaction go deep?

Barbara

Hi Barbara - apparently the Spray A will react to various degrees from that nice parchment color to deep yellow-ish brown yuck. I got the yuck. It did blast off in most areas, with a couple light areas that were not too yellowish - rather more of that parchment color you mentioned. Oddly, after blasting though, the nice creamy color of the french vanilla lightened up to more of an off white. Odd circumstance, because I blast Fr Vanilla all the time (not to remove Spray A though) and it retains the beautiful color and shading. It didn't after the Spray A incident and I don't know why. Perhaps I blasted deeper than normal to remove the muddy yellow. I just don't know for sure why it did that, but it did. (I mostly use it on edge, or broken up chunks because I love the shading and variations in color) I just keep Spray A away from it now.

And Kelly - try Super Spray for Fr Vanilla instead of Spray A. No lead = no reaction, I'm guessing. I haven't tried it though, so you may want to test.

KAG wrote:

Jackie Beckman wrote:Don't put Spray A on French Vanilla unless you want mustard yucky yellow. I learned that one the hard way. Its a reaction you want to avoid.

Thanks Jackie - THAT'S GOOD INFO TO KNOW !

...Kelly

Here are some test piece photos of pattern bar slices, scrubbed but not sandblasted. Black and French Vanilla Bullseye:



top left: clear cap
top right: spray A
Bottom left: no cap left - some devit around the edges
Bottom right: superspray - much haze (hard to see in this photo)

Steve

How odd Steve that you just happen to have that handy to post! You truly are a font of information! That will help Kelly far more than any explaination.

Jackie

Thanks for the picts Steve. Interesting. The bottom right with superspray appears to have that yellow parchment that Barbara's talking about. Interesting too that the "no cap" has devit. hhmmm

I was kinda concerned that sandblasting fr. van. would remove the creamy color. Good to know that's not going to be a problem.

Thanks for the time and wisdom. (Kiss emoticon here if I could find one).

...Kelly

Jackie Beckman wrote:How odd Steve that you just happen to have that handy to post! You truly are a font of information! That will help Kelly far more than any explaination.

Jackie

Yes. And I made these pattern bars in your garage.....

Steve

[quote="Jackie Beckman"](I mostly use it on edge, or broken up chunks because I love the shading and variations in color.)

IF I am going to use French Vanilla, I often cast up a slab of frit and then use that. I love love love the color breaks. It kind of reminds me of going to a local farm with my grandfather to buy unpasteurized (gasp!)fresh milk with the cream on top. That milk was so pretty and so yummy.

Barbara