From bubbles to thin fire paper haze

childersstudio · Post by **childersstudio** » Wed Sep 24, 2003 9:43 am

I am a new fuser who was having trouble with bubbles in 15" plates. I am using Bullseye double rolled (-30), 2 layers of clear, smooth sides together, plus a third partial layer of transparent decoration, smooth side down. After much experimentation with slowing down schedules and adding holds for bubble squeeze, I got the bubbles down to an acceptable size. At that point however, the Bullseye thin fire paper began adhering underneath the plates to the point of leaving a milky white haze even after I scrub it with soap and water and a non-scratch Scotch Brite pad. Bullseye had no answer but the Warm Glass Bulletin Board. My kiln is a Denver Glass 60. What should I use to get off the haze, and what can I do to avoid it in the first place?

Tony Smith · Post by **Tony Smith** » Wed Sep 24, 2003 10:01 am

What is your firing schedule? I'm just guessing that you are firing way too hot, but that's just a guess. I haven't seen the thinfire stick like that, but I haven't tried any of the new formulation either.

Tony

Brock · Post by **Brock** » Wed Sep 24, 2003 11:10 am

. . . and what can I do to avoid it in the first place?

Use kiln wash. Brock

childersstudio · Post by **childersstudio** » Wed Sep 24, 2003 11:21 am

Tony,
I took your sandblasting class at Warm Glass Weekend. Thank you, it was excellent. I do wish Brad had given you more time; I wanted to hear more.
I think you're right on the "too hot" aspect, but backing off brings back the bubble problem. I just went out to the studio look at yesterday's experiment- no thin fire sticking, but bigger bubbles and not a totally flat fuse (a little bit of rounded contour). Yesterday's schedule was a 600 per hour ramp to 1550, no hold at 1550 or on the way up, then zero ramp down to the annealing hold, etc.
The two schedules that brought thin fire sticking were as follows:1). Ramp at 240 per hr to 1160, 60 minute hold. Ramp at 360 per hr to 1225 with a 45 minute hold. Ramp at 180 per hr to 1460 with a 40 minute hold. then zero ramp down to annealing, etc. This bizarre schedule gave me the best bubble result of any schedules I have tried Is there any physics behind holding at 1160, or is it something the person who gave me this schedule just threw in and kept whren the result was good?
2.)Ramp at 996 per hr to 900, no hold. Ramp at 240 per hour to 1160, 30 minute hold. Ramp at 180 per hour to 1600, zero hold. Zero ramp down to annealing, etc.

charlie · Post by **charlie** » Wed Sep 24, 2003 11:31 am

try something like this:

300/hr to 1150, hold 10
50/hr to 1250, hold 0
600/hr to 1480, hold 20
anneal

the hold at 1150 lets the glass settle down. the slow ramp to 1250 squeezes out the bubbles. after that, you can go really fast. i think you want to not go so high, but hold at a lower temp to do the fusing.

childersstudio · Post by **childersstudio** » Wed Sep 24, 2003 11:51 am

thanks, Charlie I'll give that a try

Tony Smith · Post by **Tony Smith** » Wed Sep 24, 2003 12:39 pm

What Charlie said... great schedule!

Tony

charlie · Post by **charlie** » Wed Sep 24, 2003 12:45 pm

Tony Smith wrote:What Charlie said... great schedule!

Tony

actually, i can't take credit for it. i got it from cynthia, who i believe got it from someone else. i used it to make 10"x20" tiles without ANY bubbles at all.

childersstudio · Post by **childersstudio** » Wed Sep 24, 2003 3:39 pm

Thanks, Brock, Tony, and Charlie. Any suggestions on getting the white film off when I don't have a sandblaster yet? Charlie, I just started a firing on that schedule of yours- can't wait to see how it turns out.

Barbara Muth · Post by **Barbara Muth** » Wed Sep 24, 2003 7:18 pm

you can get a full fuse by holding at a lower temp. I get a nice full fuse at 1420 with a 15 minute hold.

childersstudio · Post by **childersstudio** » Thu Sep 25, 2003 3:36 pm

I tried Charlie's suggested schedule yesterday. It produced the very best non-bubble result of any schedule I have tried- that part was fantastic. It did, however, still produce some thin fire paper haze underneath the plate on the outer edge- from the edge to about an inch inwards. The thin fire paper is not curling over the plate, the residue is only underneath. I am not quite where I want to be yet.

Brock · Post by **Brock** » Thu Sep 25, 2003 3:41 pm

childersstudio wrote:I tried Charlie's suggested schedule yesterday. It produced the very best non-bubble result of any schedule I have tried- that part was fantastic. It did, however, still produce some thin fire paper haze underneath the plate on the outer edge- from the edge to about an inch inwards. The thin fire paper is not curling over the plate, the residue is only underneath. I am not quite where I want to be yet.

I say again, lose the thin fire and use kiln wash. IT WORKS! Brock

Cynthia · Post by **Cynthia** » Thu Sep 25, 2003 4:26 pm

Brock wrote:I say again, lose the thin fire and use kiln wash. IT WORKS! Brock

Childers Studio said he/she has a Denver kiln. Chances are that the shelf in this kiln is a fiber board. If that is the case, using thinfire or fiberpaper is probably Childer's only option to keep the shelf from getting torn up.

Unfortunately, some of us have no option but to use a paper as a separator, and kiln wash alone isn't an option. I am open to any suggestions of a better way to fire on these fiber board shelves and not use papers. I haven't found it yet, but that doesn't mean that there isn't a way.

childersstudio · Post by **childersstudio** » Thu Sep 25, 2003 4:29 pm

Brock,
Thanks for repeating your suggestion to use kiln wash instead of thin fire paper. I haven't jumped on your idea sooner because I am still so new at this that I get chicken about taking what seems on the surface to be the more complicated way with more use of chemicals (as if fired thin fire paper was any good for you as you remove it for the next firing). I have fiberboard shelves that do get little dings in them as you remove your pieces after firing, so I thought the thin fire paper would produce a smoother bottom. I also thought using paper would be far more time efficient that kiln washing my shelves when the inside of my kiln is almost 2 1/2 by 5 feet. It took me forever to do it as a shelf protection before my first load. If I cannot get the balance of the bubbles and paper sticking under control I will try your suggestion and appreciate knowing I have that out.
P.S. I attended one of your slide sessions at the Warm Glass Weekend and found it very helpful. Thanks so much.

Brock · Post by **Brock** » Thu Sep 25, 2003 4:31 pm

Cynthia wrote:
Brock wrote:I say again, lose the thin fire and use kiln wash. IT WORKS! Brock
Childers Studio said he/she has a Denver kiln. Chances are that the shelf in this kiln is a fiber board. If that is the case, using thinfire or fiberpaper is probably Childer's only option to keep the shelf from getting torn up.

Unfortunately, some of us have no option but to use a paper as a separator, and kiln wash alone isn't an option. I am open to any suggestions of a better way to fire on these fiber board shelves and not use papers. I haven't found it yet, but that doesn't mean that there isn't a way.

Well then, you can fit 3 20 x 20 mullite shelves in it. Brock

charlie · Post by **charlie** » Thu Sep 25, 2003 4:41 pm

Cynthia wrote:
Brock wrote:I say again, lose the thin fire and use kiln wash. IT WORKS! Brock
Childers Studio said he/she has a Denver kiln. Chances are that the shelf in this kiln is a fiber board. If that is the case, using thinfire or fiberpaper is probably Childer's only option to keep the shelf from getting torn up.

Unfortunately, some of us have no option but to use a paper as a separator, and kiln wash alone isn't an option. I am open to any suggestions of a better way to fire on these fiber board shelves and not use papers. I haven't found it yet, but that doesn't mean that there isn't a way.

i've heard this a bunch of times, but i've been using a 1.5" fiber board shelf for almost a year now without using paper. i make sure there's a very thick layer of wash on it. i've only sanded it down to the raw board once in the year; i just put another few layers on after every 2 full fuses. when a small piece of wash gets pulled up by sticking to the back of something, i just fill the hole with more wash. i've never had any of the board pull up on a piece.

when i do pot melts, i put down a thick layer of dry baby powder (pure talc kind). that never sticks at all, even when firing that to 1650.

childersstudio · Post by **childersstudio** » Thu Sep 25, 2003 4:45 pm

Cynthia Wrote:Childers Studio said he/she has a Denver kiln. Chances are that the shelf in this kiln is a fiber board. If that is the case, using thinfire or fiberpaper is probably Childer's only option to keep the shelf from getting torn up.

Cynthia, Thanks for the feedback. You are exactly right and were writing your response as I was writing mine. When contemplating Brock's suggestion I did go back to look at what Denver Glass had recommmended about wash/paper on the shelves; I had just remembered them mentioning paper. They had said either way, but a local glass artist with a Denver Glass kiln had recommended paper on top of the shelves to give a smoother finish.

Cynthia · Post by **Cynthia** » Thu Sep 25, 2003 4:57 pm

Brock wrote:Well then, you can fit 3 20 x 20 mullite shelves in it. Brock

This is a long winded way to reiterate, that kiln washed mullite isn't necesarrily a realistic option for every situation and for many good reasons (unfortuantely).

Your suggestion is good, but to fill a fiber kiln with mullite defeats the thermal and efficiency benefits of having a fiber kiln along with the benefit of having a seamless shelf. Using mullite in a fiber kiln creates a heat sink that makes firing with consistent and even heat more dicey and difficult. I have been around the block on this one with Denver, along with other fiber kiln owners.

The mullite shelves are an option to be sure for some. For me, I need a seamless shelf as large as the kiln floor to have all the available surface I can get to fire on (my work to date is ending up being larger than 20"), so the three mullite shelves aren't a realistic option. That's my universe though...so for others this may be a very reasonable option.

I don't remember the manufacturer (a German company? An Australian company?), but someone out there is fabricating a honeycombed, extruded mullite (or similar clay material) shelf that is relatively lightweight and can be made to order. A search in the archives may bring up that thread if interested in obtaining a large, seamless mullite like shelf.

childersstudio · Post by **childersstudio** » Thu Sep 25, 2003 5:06 pm

Charlie,
Thanks for the scoop on how you care for your fiber board shelves; it's a very valuable piece of info that I haven't come across in the books. Between you and Brock, I need to expand my thinking about paper and wash and my fiberboard shelves.
Sorry for the repetitive message - I can't find where it says you can delete a message on the board.

Brock · Post by **Brock** » Thu Sep 25, 2003 5:09 pm

Cynthia wrote:
Brock wrote:Well then, you can fit 3 20 x 20 mullite shelves in it. Brock
This is a long winded way to reiterate, that kiln washed mullite isn't necesarrily a realistic option for every situation and for many good reasons (unfortuantely).

Your suggestion is good, but to fill a fiber kiln with mullite defeats the thermal and efficiency benefits of having a fiber kiln along with the benefit of having a seamless shelf. Using mullite in a fiber kiln creates a heat sink that makes firing with consistent and even heat more dicey and difficult. I have been around the block on this one with Denver, along with other fiber kiln owners.

The mullite shelves are an option to be sure for some. For me, I need a seamless shelf as large as the kiln floor to have all the available surface I can get to fire on (my work to date is ending up being larger than 20"), so the three mullite shelves aren't a realistic option. That's my universe though...so for others this may be a very reasonable option.

I don't remember the manufacturer (a German company? An Australian company?), but someone out there is fabricating a honeycombed, extruded mullite (or similar clay material) shelf that is relatively lightweight and can be made to order. A search in the archives may bring up that thread if interested in obtaining a large, seamless mullite like shelf.

All my kilns are fibre and I use all mullite shelves. For 20 years. Jackie has the same kiln and she uses 3, 20 x 20 shelves and 3, 20 x 8 shelves to fill the space. It may affect the seamlesness on a larger kiln, but it has nothing to do with thermal efficicency. Brock

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From bubbles to thin fire paper haze

From bubbles to thin fire paper haze

from bubbles to thin fire paper haze

from bubbles to thin fire paper haze

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