new to kiln

[archie]

morning, hope this isn't coming up twice
My husband bought me a Skutt814 for Christmas, I haven't tried it out yet, just got wired yesterday, thought I would practice with coasters but wandered if anyone has ever done wine/beer bottles on their side, thanks for any suggestions and I have learnt lots from checking in here and reading lots. One more thing, is it a good idea to heat up the kiln washed shelf before firing? (if I can figure out how to just heat the kiln for that purpose!), told you I am new at this!!

[Brock]

morning, hope this isn't coming up twice
My husband bought me a Skutt814 for Christmas, I haven't tried it out yet, just got wired yesterday, thought I would practice with coasters but wandered if anyone has ever done wine/beer bottles on their side, thanks for any suggestions and I have learnt lots from checking in here and reading lots. One more thing, is it a good idea to heat up the kiln washed shelf before firing? (if I can figure out how to just heat the kiln for that purpose!), told you I am new at this!!

It is important to pre-fire the kiln washed shelves, especially as your work gets bigger. Many people have done bottles, tons in archive. Brock

[Nancy Juhasz]

Hhi, There is a tutorial on firing bottles on this site. The schedule is good for my Skutt GM814. Happy slumping. Read the book that came with your kiln from cover to cover so that you understand how it works. Don't forget the first firing which I think is 1550 over a 3 hour period. This is in the book. Nanc

[archie]

thankyou

[Bob]

Hey Brock,

I have a stupid question (not my first). Why do people prefire kiln shelves? I guess the answer is buried somewhere in the archives. I have never prefired my shelves. I do ensure that they are dry (bone dry... which ain't hard in Alberta). I generally wash the shelf(ves) at the end of a session in my studio and then lean the shelves against a wall. The breeze from an oscillating fan dries them overnight and they are ready to go. I can get several firings, depending on the glass type etc, from each application of wash.

The moisture in the shelf issue, and the impact on gas trapped between the glass and the shelf, has always been a red herring to me. Any vapours from moisture within the shelf would take the path of least resistence when trying to escape. I would think that this would be down through the permeable bottom of the shelf. It is way easier than working through the relatively impermeable layer of kiln wash covering the top of the shelf.

Does preheating the shelf do anything other than dry out the shelf? Does it harden the layer of wash? I'd rather ask you than search through the archives.

Cheers

Bob

[glassart]

I received a Jen-Ken Kiln for Christmas and finally got around to firing it up yesterday. For my first firing, I took 2 green "Dutch Windmill" beer bottles and melted them. Didn't realize this was going to be an all day event though!
Anyway, opened the Kiln this morning and both bottles had melted perfectly. I was truely amazed.
The book written by Warm Glass is excellent and answered a lot of questions as I went through the process. Highly recommend it. Next, want to try a wine bottle but will have to get one that fits (have a 13" shelf).
Good luck on your first firing!

[Brock]

Hey Brock,

I have a stupid question (not my first). Why do people prefire kiln shelves? I guess the answer is buried somewhere in the archives. I have never prefired my shelves. I do ensure that they are dry (bone dry... which ain't hard in Alberta). I generally wash the shelf(ves) at the end of a session in my studio and then lean the shelves against a wall. The breeze from an oscillating fan dries them overnight and they are ready to go. I can get several firings, depending on the glass type etc, from each application of wash.

The moisture in the shelf issue, and the impact on gas trapped between the glass and the shelf, has always been a red herring to me. Any vapours from moisture within the shelf would take the path of least resistence when trying to escape. I would think that this would be down through the permeable bottom of the shelf. It is way easier than working through the relatively impermeable layer of kiln wash covering the top of the shelf.

Does preheating the shelf do anything other than dry out the shelf? Does it harden the layer of wash? I'd rather ask you than search through the archives.

Cheers

Bob

Have all our original processes become passe? I pre-fire because . . . . . .

. . . . . because I was taught to do that in my first fusing course.

I pre-fire to 1450, every shelf, every time, except when making small objects that couldn't possibly trap air/steam/water. Going that high in a pre-fire supposedly also eliminated chemical steam from quartz inversion, a subject about which I know nothing. I do know I never get bubbles. Brock

[Amy on Salt Spring]

I pre-fire to 1450, every shelf, every time, except when making small objects that couldn't possibly trap air/steam/water. Going that high in a pre-fire supposedly also eliminated chemical steam from quartz inversion, a subject about which I know nothing. I do know I never get bubbles. Brock

That's interesting. I used to do that--followed the directions on the bucket of BE kilnwash but as time went on I started thinking it was overkill and kept dropping the temp and time. Now I prefire to 500 and hold there for 5 or so minutes until the color changes (lighter pink) indicating its completely dry. Never had trouble with bubbles. For once my impatience actually helped me out...
-A

[charlie]

i've never prefired a shelf. just this last weekend i brushed on about 6 coats, then a couple of coats of plain hot water to smooth it down. i put a fan on it to dry for about 15 minutes, and fired a 20" round blank on it with no bubbles at all. it probably wasn't completely dry since it felt cold to the touch, and it was probably only 65F in my studio and raining outside so there was high humidity at the time too.

[archie]

morning from BC, I prefired my shelf to 500 and did my first firing, coasters as is suggested, the two I did exactly as the book suggested turned out fine except that the edges were a little ruff, another I put a 2" square of aluminun foil between layers and got a couple of bubbles that made it unusable, another I put some small slivers of regular glass between and got a few bubbles, another I put some baking soda between layers and the bubbles were so large that it is totally unusable. I was surprised by how long it took-9hrs-didn't expect that, I figured these coasters are probably worth about $20, cad each!! any suggestions on the cost of running this kiln-gm814- do most people use 2 shelves? should I have prefired the shelf hotter, do I kiln wash only when I start to see through it? do you vacuun the shelf between each use? thanks, Archie

[charlie]

from http://www.clt.astate.edu/wrowe/ceramic ... ocess.html:

Quartz Inversion

All clay contain quarts, either naturally or in the form of added: free silica. When temperature advances, the crystals of quartz rearrange themselves into a slightly different order. The rearrangements are accompanied by slight changes in volume. When 573oC us reached, quartz crystals undergo a change known as a change from alpha to beta quartz. This is marked by a 2% increase in volume. Reversible upon cooking, the quartz changes from beta to alppha and resumes its original crystalline form and size. This change of volume, though slight, must be done slowly to avoid damage to the ware. A large percentage of ware which comes from the kiln cracked is damaged by either too rapid heating or too rapid cooling at this critical temperature. In uneven firing kilns, one must by very careful with large pieces.

quartz inversion can't cause bubbles since it is only the size of the crystals that are changing, not emitting gasses.

[Brock]

All clay contain quarts . . .

Of what, one wonders.

[Alecia Helton]

I'm probably showing my ignorance ... I was taught that kiln wash is only effective at full fusing temperature once. So if you prefire at 1500, haven't you already used it?

Bob, I really appreciate you asking the question about prefiring because I've been puzzled by it also. I was taught to completely dry the shelf, period. That kiln wash could be reused if it had not been taken to full fusing temps, but if it had, you had to reapply. So the discussion about prefiring shelves to 1500 has really confused me.

I ocassionally get bubbles. When I do, I can usually trace it back to not drying the kiln wash. So now I put shelves in the kiln to 150 for 10 min, or in front of the space heaters for an hour or so.

I'm learning so much from this Board.

Alecia

[Bob]

Hi Alecia,

There are no rules in kilnformed glass. And if there were... they were made to be broken (or at least tested)

There are Laws... the physcial and chemical properties that will occur regardless of what we with glass in teh kiln. Laws can be twisted but not broken.

Cheers,

Bob

[Brock]

from http://www.clt.astate.edu/wrowe/ceramic ... ocess.html:

Quartz Inversion

All clay contain quarts, either naturally or in the form of added: free silica. When temperature advances, the crystals of quartz rearrange themselves into a slightly different order. The rearrangements are accompanied by slight changes in volume. When 573oC us reached, quartz crystals undergo a change known as a change from alpha to beta quartz. This is marked by a 2% increase in volume. Reversible upon cooking, the quartz changes from beta to alppha and resumes its original crystalline form and size. This change of volume, though slight, must be done slowly to avoid damage to the ware. A large percentage of ware which comes from the kiln cracked is damaged by either too rapid heating or too rapid cooling at this critical temperature. In uneven firing kilns, one must by very careful with large pieces.

quartz inversion can't cause bubbles since it is only the size of the crystals that are changing, not emitting gasses.

I told you I knew nothing about it. I was taught by Boyce Lundstrom, Ruth Brockman, Rick LaLonde, Gil Reynolds, and others to ALWAYS pre-fire shelves. It works for me. I'm not going to change because some people get away with it.

[Amy on Salt Spring]

I'm probably showing my ignorance ... I was taught that kiln wash is only effective at full fusing temperature once. So if you prefire at 1500, haven't you already used it?

Alecia

That is what I learned from the books I taught myself with as well--however I find that I can fire a couple of times--sometimes many many times depending on the temperatures I'm using and the kind of glass, on the same kiln wash. You kind of get a feel for when its been long enough that you are risking having it start to stick. I put only a few thin coats on because I find anything more tends to have a shorter lifespan and stick to the glass more readily. I've never had any trouble with bubbles with my drying the kilnwash at 500, but as you can see everyone has a different way of doing things.
-Amy