Holes in Full fused glass

[Vital-Spark]

I have a new Paragon Fusion 19 kiln. I have tried everything to solve a serious problem I have. If I fully fuse a 12″ x 8″ piece of Bullseye (Tekta base with any top layer ) in 1 piece or 3 pieces I get 1 or 2 holes in exactly the same place every time.

I have used the Fusenews schedules for years in my previous kiln (a Skutt) with well controlled bubble results. I used the recommended bubble squeeze 300 > 900 hold 15 then 100 > 1225 Held 30 or even for an hour but a clean elongated hole over 1.5″ appears every time.

I am a pretty experienced fuser & just cannot fathom why this is happening. This kiln BTW has the ceramic fiber lid & comes with a very heavy shelf probably 1″ thick. I fire on Bullseye thinfire paper too.

If anybody has this kiln or can shed any light on my problem before I see if Paragon can help please let me know. I’m wasting acres of glass trying different things!!

[wordana]

Could it be the shelf? If it is uneven (has “dips”), these will cause air pockets, that will cause bubbles, that will cause holes.

 

This is assuming you are using at least two layers of glass — if you are using 1 layer, the glass is too thin and causing holes.

Dana W.

Jester’s Baubles Fused Glass Designs

http://www.jestersbaubles.com

[Vital-Spark]

I am using 2 layers. The shelf – well how flat is flat is a good question which I took up with Paragon. When a 17″ straight edge is layed on the shelf you cal slip 2 thickness of letter paper under it at the middle. So the shelf is not perfectly flat. But is that not flat enough? So I am in the prcoess of turning the shelf to test on the other side.

Paragon could not guarantee that a new shelf would be any flatter so credited me with the price of a shelf. Personally I would rather have a working kiln. This one is un-useable unless I can solve this problem. Unfortunatly finding a 17″ square shelf that is not Paragon is like finding hen’s teeth!!

[wordana]

Clay-king:

http://www.clay-king.com/kilnshelves.htm#shelves

 

Flipping the shelf is a good idea. Also, you might try firing on 1/8″ fiber blanket and see if that resolves the problem. The fiber blanket would let the air escape from under the piece — not a good long-term solution, however.

Dana

Jester’s Baubles Fused Glass Designs

http://www.jestersbaubles.com

[Vital-Spark]

Thought I would update. The shelf is flat. I fire on Thinfire so all the issues caused by other potential bubble forming eliminated.

I am trying a slow fire at the bubble sqeeze range of 300>900, 50>1225 hold for 1 hour. That frankly is a slow as I wish to go, perhaps 11/2 hrs. Then on to full fuse.

I have said to Paragon I will fire on a piece of 1/8 fibre paper then as a final test I have another shelf thats 5/8″ which I will top with vermiculite ensure flatness with the 50>11/2 hr hold. if that doesnot work the kiln goes.

Frankly I have spent weeks & acres of glass trying to solve this instead of producing projects. Unless they can do me a deal of some kind I’m off back to Skutt.

[Vital-Spark]

Latest up date. Bought a 5/8″ mullite from local supplier, probelm solved!! There are air pockets WITHIN this shelf. Unusual I suppose. Not being flat is pretty common but air pockets I would never have thought of.

Thnx all who offered suggestions

[Author]

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