Devit Problem with BE

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GuyKass
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Devit Problem with BE

Post by GuyKass »

I have sort of a run of the mill problem, but I'm pulling my hair out because no matter what I do, I can't solve it. I was hoping someone here might have some useful input.

I am starting to make a ton of frames for a customer, and I am using Bullseye because they specified it. I normally use 96 stuff.

No matter what I do, I am getting what looks like devit on the top layer of the glass when taking it to a full fuse. The interesting part is that it seems to have the exact pattern that the glass has before it's fired.

I am cleaning it like always, I use Glass Plus with some alcohol mixed it. It's always worked perfectly with Spectrum and Uro.

I wasn't happy with the first batch firing so on the second, I decided to keep it as short as possible.

400/hr to 1250 hold for 30 (probably don't even need the hold, but it's what I've been doing)
600/hr to 1480 hold for 10
ASAP to 900 hold for 30 (I am crashing the kiln to get down to 1000 as fast as I can go.
150/hr to 700 Off and letting it cool naturally (in a brick kiln)

I am firing on BE Thinfire, but I always vent. I keep the plug out of the peephole the entire process.

If any one has any ideas I would really appreciate the input. Once I figure out why it's happening I will just sandblast these two sets and re-fire, but in the meantime, I don't want to keep going this way.

Anyway, thanks in advance,
Guy
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Marty
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Re: Devit Problem with BE

Post by Marty »

First thought: try kilnwash.

Also, you've got the kiln space so take your time and fire lower and longer (I don't think that will have anything to do with your issue but it's good practice).
JestersBaubles
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Re: Devit Problem with BE

Post by JestersBaubles »

what's on top? If it's Tetka, it's notorious for deviting with thinfire. That's always seemed ironic to me.

Dana W
David Jenkins
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Re: Devit Problem with BE

Post by David Jenkins »

Is the whitish "stripe" the devit you're talking about?

Did you use a piece of TF that was the size of the frame and the interior (empty) area? Or did you cut out a ring (topologically speaking) that was the width of just the glass plus a little extra? I'm wondering if you had a large expanse of uncovered TF, that that might have contributed some way to the contamination?
Dave Jenkins
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rosanna gusler
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Re: Devit Problem with BE

Post by rosanna gusler »

i would lower your first hold to 1100f or a little less. or put in another step with a hold there. your first hold is high enough for the glass to be soft enough grabbing thinfire smutch before it has a chance to get out of the kiln. maybe prop the lid a quarter inch at first. or just use kiln wash.
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GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

Thank you all. I think the easiest thing to try first is eliminating the TF and lowering the initial hold.

Normally my schedules are a bit more logical than this, but I started thinking to keep the glass in the heat as short a time as possible.

Dave, I just popped an entire sheet of paper in and layed the pieces on that.

And Dana, no the top sheet is one of their steel blues on top of the streamer sheet.

If it doesn't work, I'll come back whining a bit more.

Again, thanks to the 4 of you.

Guy
David Jenkins
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Re: Devit Problem with BE

Post by David Jenkins »

Why not try cutting a "ring" of TF - just enough to separate your glass from the shelf?
Dave Jenkins
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GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

Hi Dave-

Actually after I wrote the last note, that is what I decided to try. I combined your and Rosanna's advice.

If that doesn't do the trick I will just go to KW. My shelves are coated and in good shape anyway, I just thought using Thinfire the pieces might come out even better. I will see this batch tonight with any luck at all.

Thanks again,

Guy
Morganica
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Re: Devit Problem with BE

Post by Morganica »

Take out the thinfire--I never use it (or any fiberpaper) with a finish firing unless I'm planning to coldwork--and you may need one or two firings to completely clear the kiln. I think if you cut out a piece of thinfire to conform exactly to the footprint of the piece you'll have fewer issues, but they won't go away entirely. You'll still get the outgassing and probably see scum at the edges of the piece.

But steel blues..when I've done tack-fuses with steel blue I'll sometimes see what looks like the start of devit scum surrounding the areas of metallic filming. I think it's simply an incomplete filming reaction although I've no real basis other than personal experience to say that's the cause.

Are you seeing the scum with other glasses as well?
Cynthia Morgan
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GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

No, but this is the first time I've ever fired anything from BE other than some casting billets.

Someone else pm'd me and said it happens with BE's steel blues unless you somehow cap with clear.

When I first bought the glass it struck me for whatever reason, that it must have a fair amount of copper in it (I don't know what made me think it, just doing too much for too long) and I am starting to think that is the problem.

At the moment I have a load in with a minimum amount of paper under the glass, I've slowed down the beginning of the firing and I've cracked the kiln about 1/2" for additional venting.

If this load comes out crappy, I will do the layups reversed and see if that helps. I have a sneaking suspicion that is what is going to fix this.

Thanks again,

Guy
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Re: Devit Problem with BE

Post by Valerie Adams »

Looks like the scum I started getting with Thinfire.
Morganica
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Re: Devit Problem with BE

Post by Morganica »

GuyKass wrote:No, but this is the first time I've ever fired anything from BE other than some casting billets.

Someone else pm'd me and said it happens with BE's steel blues unless you somehow cap with clear.

When I first bought the glass it struck me for whatever reason, that it must have a fair amount of copper in it (I don't know what made me think it, just doing too much for too long) and I am starting to think that is the problem.

At the moment I have a load in with a minimum amount of paper under the glass, I've slowed down the beginning of the firing and I've cracked the kiln about 1/2" for additional venting.

If this load comes out crappy, I will do the layups reversed and see if that helps. I have a sneaking suspicion that is what is going to fix this.

Thanks again,

Guy
I guess I don't get why the paper is necessary if you're already kilnwashing the shelf?
Cynthia Morgan
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GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

Really just figured it would give me a better finish. In my head, nothing is ever good enough so I am always trying to find a better way.
Susanbuckler
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Re: Devit Problem with BE

Post by Susanbuckler »

I keep the plug out of the peephole the entire process.
why?

Susan
Susan Buckler
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GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

My logic is so that way anything that may be in there other than glass such as Thinfire, humidity, any types of adhesive I may have used, etc. have a way to escape. And I don't think it slows firings down, nor do I think it wastes much energy.
Lynn Perry
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Re: Devit Problem with BE

Post by Lynn Perry »

Hi, Cynthia. I use paper and also coat my shelves with kilnwash. However, I only coat them once about every five years unless I have spillage which is the reason they are coated at all. Perhaps Guy does the same.
Lynn Perry
JestersBaubles
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Re: Devit Problem with BE

Post by JestersBaubles »

GuyKass wrote:My logic is so that way anything that may be in there other than glass such as Thinfire, humidity, any types of adhesive I may have used, etc. have a way to escape. And I don't think it slows firings down, nor do I think it wastes much energy.
Perhaps it doesn't matter much, but it will create a cold spot.

Dana W.
LDGlass
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Re: Devit Problem with BE

Post by LDGlass »

I stopped using Thinfire because I got scum so often. I use Papyros exclusively if I'm going to use shelf paper but kiln wash always works best for me.
GuyKass
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Re: Devit Problem with BE

Post by GuyKass »

It's funny, out of literally thousands of pieces, only had a problem like this once before and that was on a cast piece.

It turned out (and that's necessarily to let Thinfire off the hook) but if I flip them and use the clear/stringer sheet as a cap and put the blue on the bottom, the shmutz is gone. Someone sent me a note to try it as he said it happens with all of the BE Steel Blue colors.

It was really the first time I used anything from Bullseye "for real."

I really appreciate all the thoughts and suggestions.

Thanks again,

Guy
Steve Immerman
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Re: Devit Problem with BE

Post by Steve Immerman »

I agree with Marty, try eliminating the Thinfire. Also, eliminate the hold at 1250. Try a lower top temp. This should work just fine with Bullseye glass.

http://www.clearwaterglass.com/Tutorial ... ation.html

http://www.clearwaterglass.com/Tutorial ... Frame.html

Steve
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