2 shelf firing? - WarmGlass.com

2 shelf firing?

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Lauralei
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2 shelf firing?

Postby Lauralei » Sat Dec 06, 2003 8:50 pm

Hi - Can anyone offer advice.. pros & cons of firing with 2 shelves ? I have a Paragon GL24 ADTSD...elements in top,side & doors... and wonder if I should know if this is a bad thing before I lose 2 full shelves of BE glass that is set to be fused for blanks... any help is appreciated. Thanks
Lauralei

Tyler Frisby
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Postby Tyler Frisby » Sat Dec 06, 2003 8:54 pm

Yeah Id like To know Too , I have a Paragon GL-44 ADST

Side And Top elements. !
thanks

PaulS
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Postby PaulS » Sun Dec 07, 2003 12:38 pm

The top shelf will fire hotter than the lower shelf.

Glass fired on the top shelf won't look the same as that fired on the lower shelf.

Why scrimp on a days' firing when what you are making will endure thousands of years? Surely it's better to take your time and do it properly, one at a time?

The archaeologist will dig it up and say to their colleague; 'Hey look, they must have stacked their kiln-shelves to rush firing these pieces -see how the edges aren't fused properly?' :)

...slow boy but patience goes a long way

.
It ain't where you're from, it's where you're at!

Geri Comstock
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Postby Geri Comstock » Sun Dec 07, 2003 2:21 pm

I tried this a few years ago in my kiln, having gotten some advice from Graham about it. The top shelf was "done" and the bottom shelf wasn't. In addition, stuff dropped off the top shelf onto the glass on the bottom shelf, leaving me with a mess. I tried it about 3 times and never had good results, so I gave up on it.

Geri

Pam
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Postby Pam » Sun Dec 07, 2003 2:36 pm

I have a Paragon GL 24 also and have been thinking about firing multiple shelves. Isn't there a way to shut off the top heat and just fire the side elements? Wouldn't that reduce the problem of the top shelf firing faster?

Barbara Muth
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Postby Barbara Muth » Sun Dec 07, 2003 5:42 pm

Pam wrote:I have a Paragon GL 24 also and have been thinking about firing multiple shelves. Isn't there a way to shut off the top heat and just fire the side elements? Wouldn't that reduce the problem of the top shelf firing faster?


Perhaps but you would have to slow down your schedule so much to avoid bubbles and thermal shocks that you would end up not saving much time. And you would have to experiment a lot with your pieces before hitting on the right schedules. I thought about doing it, decided that I didn't have the time to figure it all out and am happy with my one shelf.

Also, for those who think 2 shalves save time, cooling down is much slower going because, just like the first one, the second shelf holds a lot of heat.

Barbara
Barbara
Check out the glass manufacturer's recommended firing schedules...
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Lauralei
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Postby Lauralei » Sun Dec 07, 2003 6:12 pm

Lot's to think about.. Thanks for everybody's ideas.. I certainly hope I don't find a big drippy mess like Geri said!

I didn't turn off my top elements - because - duh- I just didn't think of it... I'm not sure 2 shelves is worth it either - but as an experiment and since I don't have alot of days free to fire. I gave it a try.. I'll let you know how it turns out.
The schedule I used is
350 dph - 1150 hold 20
150 dph - 1250 hold 20
500 dph - 1480 hold 30
afap to 960 hold 1 hr
150 to 700 - off

thanks all
Lauralei

Dani
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Postby Dani » Sun Dec 07, 2003 7:00 pm

I fire 2-3 shelves in my side-firing ceramics kiln without problems. In fact, I can't recall the last time I only fired with one shelf. There is a temp difference between shelves and you should become familiar enough with your own kiln's differences to adjust what pieces you fire on each shelf... for example, the smallest pieces will fire fine on a cooler shelf, and the larger/thicker pieces on your hottest level. It doesn't take long to be able to maximize your power and time useage. This is where that notebook documenting each firing comes in real handy! :wink:

Lauralei
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Postby Lauralei » Sun Dec 07, 2003 7:12 pm

thanks Dani! that's encouraging - although I should probably done a test on the 2 shelves first - but what the heck -- seem there's just no way to learn without making a few boo boos
Lauralei

Susan Schroeder
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Postby Susan Schroeder » Sun Dec 07, 2003 10:04 pm

I have a much smaller kiln, an 11" JenKen, with top elements only. When doing jewelry, I often use two shelves - a full fuse on the top shelf and a fire polish on the bottom shelf. I go fairly fast with pieces that small so the bottom shelf stays substantially cooler than the top.

This does not work at all with larger pieces where I go slower and hold longer. However, I have found that I can fire things to a nice tack fuse on the bottom shelf when firing a larger piece on the top shelf. Since I rarely have a desire to tack fuse, this is pretty much a moot point - but I know it can be done.

The only way you will know if firing two shelves will give you the results you desire is to give it a try. It will definitely give you further education about your kiln, which is not a bad thing in and of itself.

Susan

sadiesjewels
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Postby sadiesjewels » Mon Dec 08, 2003 3:06 pm

I have a very small skutt (side elements only) and often fire with two shelves - it would have been impossible to do 120 maglesses last year if I was only able to fire 6 at a time - it was pretty slow going doing 10-12!

Anyway, I pretty much do what Susan says she does and just do different things on each shelf - full fuse on the top and tack fuse/paint/firepolish on the bottom ... it really is a question of understanding your kiln and it's little foibles ... also I'm only doing small stuff and don't yet have a larger kiln to understand (getting one on Saturday - yipeee!) which might change my perspective.

Sadie

Dani
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Postby Dani » Mon Dec 08, 2003 7:27 pm

Theoretically, heat rises and the top shelf should be hottest. It isn't the case with my kiln and may not be with yours. I also have different results using two shelves as opposed to three shelves. You have to do the tests on your own kiln to find out how your beast acts.

charlie
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Postby charlie » Mon Dec 08, 2003 7:44 pm

actually, a few months ago this was discussed. the space between two shelves is actually the hottest. something to do with heat reflecting and enclosed in a cavity.

Lauralei
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Location: Annapolis, Md.

Postby Lauralei » Mon Dec 08, 2003 8:25 pm

well the results are in for the Paragon GLADTSD 24 - it ain't so pretty...
THe top shelf as you all predicted fared better at producing a full fuse that the lower shelf ... Oddly the red BE glass over clear is the only one of 4, 7" plates on top that didn't come to full fuse. The 2 Black & 1 white were perfect. The large 12" plate on the bottom with gold irid and white (all BE) center has gaps in in all the places that the 2 glasses met - so that'll be going back in ! all the little jewelry pieces fared pretty well no matter wher they were... so all in all - didn't save me a 2nd firing schedule but was worth the learning curve on this kiln... Like others said... I'm not much for tack fusing myself - so that's not so useful. But I could see a fire polish, as suggested for the lower shelf - but probably not so reguarily needed. SO Thanks again for the incredible sharing of info that goes on on this board it's really priceless.
Lauralei

Lauralei
Posts: 37
Joined: Sat Mar 29, 2003 9:35 am
Location: Annapolis, Md.

Postby Lauralei » Mon Dec 08, 2003 8:26 pm

Well the results are in for the Paragon GLADTSD 24 - it ain't so pretty...
The top shelf as you all predicted fared better at producing a full fuse that the lower shelf ... Oddly the red BE glass over clear is the only one of 4, 7" plates on top that didn't come to full fuse. The 2 Black & 1 white were perfect. The large 12" plate on the bottom with gold irid and white (all BE) center has gaps in in all the places that the 2 glasses met - so that'll be going back in ! all the little jewelry pieces fared pretty well no matter where they were... so all in all - didn't save me a 2nd firing schedule but was worth the learning curve on this kiln... Like others said... I'm not much for tack fusing myself - so that's not so useful. But I could see a fire polish, as suggested for the lower shelf - but probably not so regularily needed. So Thanks again for the incredible sharing of info that goes on on this board it's really priceless.
Lauralei

PaulS
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Postby PaulS » Tue Dec 09, 2003 5:35 am

When you come to refiring the big disk, you can help heal the places where the two glasses meet by sprinkling clear frit at the join.

Then when the glass reaches fuse temperature, it melts into the gap.

Most times, anyway.

Have fun :wink:
It ain't where you're from, it's where you're at!

Terry Ow-Wing
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Postby Terry Ow-Wing » Tue Dec 09, 2003 1:35 pm

:) I do this all the time. I use the top shelf to fire to a 1405 and underneath I only do slumps. I'm banking on a 200degree difference. I use two annealing points one for the top shelf and one for the slump underneath. Only drawback is that my slumps are well hidden under a shelf so that all of it receives heat (less) as even as possible therefore I can only put 2 to 4 items in for slump.
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