Bubbles from my shelf? - WarmGlass.com

Bubbles from my shelf?

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Sandpiper
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Bubbles from my shelf?

Postby Sandpiper » Thu May 01, 2003 1:40 pm

Okay I tried again. I fused two pieces of glass. During the fusing two giant bubbles appeared, think small hardboiled eggs. When I took the piece out of the kiln, it became obvious that the bubbles came from the shelf, because the glass was fused together and humped up together. My helpful son said flip the piece over and use the indentations for serving sushi condiments. I'll let him out of the kiln next week. I applied kiln wash prior to the firing and heated the shelf to 500 degrees and let it hold for 15 minutes or so. The kiln was vented. Did I not let the wash dry enough so the moisture formed bubbles? Can I heat it again and make the bubbles disappear. Not the shelf, the glass. Should I take my son out of the kiln before heating? Do any of you work for human services and are you coming to get me. Will I sort this stuff out? Did I make a mistake buying a kiln? Please tell my you all spent hundreds of dollars on mistakes and everything is fine now.
Thanks,
Sandpiper

Geri Comstock
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Postby Geri Comstock » Thu May 01, 2003 1:52 pm

There is a ton of information in the old archives about the causes of bubbles from kiln shelves. There are remedies, such as using fiber paper, etc.

I bought some new shelves last year from BE and haven't had a bubble since. It was definitely worth the expense...I've saved more than what I paid for them in glass and fiber paper costs.

Geri

Ron Coleman
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Postby Ron Coleman » Thu May 01, 2003 2:21 pm

Are you soaking the glass at about 1200-1225 f? To avoid getting shelf bubbles make sure you soak the glass in the 1200 range for a good 20-30 min. to let the air squeeze out between the glass and shelf. If that doesn't help get a new shelf.

Ron

If the glass is badly deformed refiring won't help much.

Diane
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Postby Diane » Thu May 01, 2003 2:53 pm

As far as your son is concerned...a long soak at about 1250 should be good enough to get the BUBBLE HEADED IDEAS out of him.
:-$ I promise not to tell Social Services
Diane

Cynthia

Postby Cynthia » Thu May 01, 2003 4:44 pm

A couple of possible solutions...some already mentioned.

Slow down your schedule between 1000 and full fuse. If you have side elements, the edges of the glass can soften sooner than the rest of the glass and "seat" (for lack of a better description) onto the shelf trapping air between the shelf and glass. When this happens, the expanding air will dome the glass...as you experienced. If you slow down your ramp up, and even consider adding a soak at somewhere between 1100-1200 to allow the glass to relax and squeeze out the air, you may eliminate bubble trouble both between the shelf and glass as well as between pieces of glass.

You may have an indentation in your shelf which makes it an evil shelf and you will probably want to replace it with a better shelf eventually. To determine if you have an indentation or warp in your shelf, lay a straight edge across it, looking all across the shelf, and see if the shelf is flat or not. If it's not, you can flip the shelf and see if the other side is flat and only fire on the good side. Start firing with fiber paper so the air can escape regardless of the condition of your shelf, or try the chad approach.

Chads can be used to stilt the glass up above the shelf. Place a small chunk (1/8") of glass that is the same as the base glass at each corner of your piece, or make a tripod of chads for a round blank. Make sure that the chads are right smack dab at the edges. What this does is allow the center of the piece to sag and touch the shelf before the edges do. As it continues to sag onto the shelf, air is effectively eased out or never even trapped to begin with.

You asked, "Can I heat it again and make the bubbles disappear?"
Not really. The glass thinned to accomodate the air, and now it will remain thin even if you get it to flatten. YOu can redesign to incorporate the area where the bubbles were by adding elements or exaggerating the area...up to you how you handle it. To get them to flatten you will need to either break the domes or fire again on fiber paper...or at least that would be how I would approach it.

You also asked "Should I take my son out of the kiln before heating? Do any of you work for human services and are you coming to get me? Will I sort this stuff out? Did I make a mistake buying a kiln? Please tell my you all spent hundreds of dollars on mistakes and everything is fine now."

To those questions I respond with: Probably, yes. No. Definitely yes. No. Yes...for the most part anyway. Just when you think you have it figured out, the trolls will come out and torture you, but that's par for the course.

I usually lock my son in his room or out of the house...Never considered the kiln, but I have one big enough for him...hmmm :roll: :-k

Steve Immerman
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Postby Steve Immerman » Thu May 01, 2003 4:56 pm

No, you didn't make a mistake buying a kiln. You will solve this problem and move on. I struggled with this bubble issue myself for quite a while years back, before figuring it out.

As for the bubbles, take a straight edge and hold it on the shelf, to see if the shelf is perfectly flat. If it is not, you'll continue to have bubbles unless you (1) use fiber paper or (2) get a new shelf. Some shelves just don't work well.

Good luck.

Steve

Sandpiper
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Postby Sandpiper » Thu May 01, 2003 7:04 pm

Thanks for all the answers. Now comes the part where I look really stupid. Gerry, what's a BE shelf?

I fused another piece. Got two bubbles again. Thought, what the hell, so I heated the kiln up until they broke. Fun, now I've got great big holes I can do something interesting with, but it kind of ruined the neat plate design I had going. I'm headed out to try the straight edge trick, and go from there. Sigh
Sandpiper

Billie Myers
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Postby Billie Myers » Thu May 01, 2003 7:08 pm

I had the same problem! I had gotten my kiln and had several successful firings, then one day everything I fired had huge bubbles. I started using thin fire shelf paper and that has worked, but, I don't like using it. It stretches and breaks leaving all kinds of designs on the back of the glass. I live at the beach and I have discovered that my shelves weren't drying completely and that was causing the huge bubbles. I now put my shelves in the kiln (500) for about 30 minutes and haven't had any problems. Good luck and I think I will try putting my son in the kiln, nothing else had worked!
Billie

Sandpiper
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Postby Sandpiper » Thu May 01, 2003 7:26 pm

Hey, I live on Lake Erie. maybe same problem. Thanks

Geri Comstock
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Postby Geri Comstock » Thu May 01, 2003 9:03 pm

Sandpiper -

In answer to your question, BE stands for Bullseye (as in the company that is one of the sponsors of this board). LOL. I forget that not everyone knows the abbreviations that some of us use.

Their shelves are made in Europe (please correct me if I'm wrong, Lani) from some material other than the mullite shelves that we get here in the U.S. My new shelves are fabulous!

Geri

Barbara Muth
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Postby Barbara Muth » Thu May 01, 2003 9:22 pm

Geri Comstock wrote:Sandpiper -

In answer to your question, BE stands for Bullseye (as in the company that is one of the sponsors of this board). LOL. I forget that not everyone knows the abbreviations that some of us use.

Their shelves are made in Europe (please correct me if I'm wrong, Lani) from some material other than the mullite shelves that we get here in the U.S. My new shelves are fabulous!

Geri


I can't wait till they get round ones!
Barbara
Barbara
Check out the glass manufacturer's recommended firing schedules...
LATEST GLASS

Ron Coleman
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Postby Ron Coleman » Thu May 01, 2003 9:45 pm

Barbara Muth wrote:
Geri Comstock wrote:Sandpiper -

In answer to your question, BE stands for Bullseye (as in the company that is one of the sponsors of this board). LOL. I forget that not everyone knows the abbreviations that some of us use.

Their shelves are made in Europe (please correct me if I'm wrong, Lani) from some material other than the mullite shelves that we get here in the U.S. My new shelves are fabulous!

Geri


I can't wait till they get round ones!
Barbara


What size round shelves do you need? Take a look.

I just bought some Acme Marls shelves from Highwater Clay and they are super flat.

http://www.highwaterclays.com/kilnsshel ... ml#shelves

Ron

Sandpiper
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Postby Sandpiper » Thu May 01, 2003 11:01 pm

Gerri, I should have figured out what BE stands for. My son had to tell me what LOL stands for. He redeemed himself so I let him out of the kiln. Next question who is the best supplier for the BE shelf and shelf wash. Any suggestions? Again, thanks for helping the rookie.
Sandpiper

Brad Walker
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Postby Brad Walker » Thu May 01, 2003 11:31 pm

Sandpiper wrote:Next question who is the best supplier for the BE shelf and shelf wash. Any suggestions?


Try Bullseye. http://www.bullseyeconnection.com/stockup.html

Sandpiper
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Postby Sandpiper » Thu May 01, 2003 11:40 pm

Thanks Brad. I was just there and e-mailed for a catalog. I figured they would just tell me to contact my local retailer. I guess you can't view the catalog on-line, or did I miss something.

I think I'm beginning to sound like an idiot. I'm really not. Honest
Sandpiper

Lynne Chappell
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Postby Lynne Chappell » Fri May 02, 2003 1:21 am

Well as for spending a ton of money on disasters, count me in. I started fusing 5 years ago, before Brad and this wonderful board, and without any instructors (other than a couple of books). I think I've made every mistake in the book. I keep them handy. When students ask what happens when you "do this", I just pull out one of my disasters and show them. They get a kick out of it and perhaps start to understand that fusing isn't something you can completely control (until you've done the same thing a lot of times) and won't be surprised when they have their own disasters.

As for your bubbles, there is lots in the archives. Check your shelves and also look to see if the bubbles are erupting where there was significantly less glass thickness.


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