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Seder Plate Mold Firing Schedule

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Seder Plate Mold Firing Schedule

Postby Kerry7140 » Thu Feb 25, 2010 3:46 pm

Please recommend a firing schedule for using the seder plate mold with 6mm of glass.

I just ruined my project and need to start over...this time following your recommendations.

The glass I'm trying to slump is Tekta 3mm on bottom and Translucent White Striker on top. I fired twice. The first time wasn't enough and the second time all of my glass puddled into the six little cups and the piece is ruined.

My first firing schedule was:
Segment 1: Ramp 200 dph to 1100 degrees and hold 30 minutes
Segment 2: Ramp 9999 to 1250 degrees and hold 10 minutes
Segment 3: Ramp 9999 to 960 and hold 1 hour 30 minutes
Segment 4: Ramp 50 dph to 720 and hold 20 minutes
Off
The result was that the glass slumped just enough that it formed the lip of the plate and slight sagging into the individual cups...but not enough.

So I called Bullseye and spoke with someone who said I needed to soak the slumping temperature for an hour. I refired the piece using the same schedule as above, but I changed Segment 4 to hold 1 hour.

The result was that all the glass pooled into the six little cups in the seder plate mold and the piece isn't salvageable.

What should I do next time?
Thanks,
Kerry
Kerry7140
 

Re: Seder Plate Mold Firing Schedule

Postby johnreeves » Fri Feb 26, 2010 12:38 pm

:? I don't get how you got puddling @ 1250, even for as long as an hour. Is your thermocouple perhaps reading as much as 100 low? That would do it!

Good luck!
John
johnreeves
 

Re: Seder Plate Mold Firing Schedule

Postby mnglass » Fri Feb 26, 2010 2:13 pm

Kerry7140 wrote:. . .
My first firing schedule was:
Segment 1: Ramp 200 dph to 1100 degrees and hold 30 minutes
Segment 2: Ramp 9999 to 1250 degrees and hold 10 minutes
Segment 3: Ramp 9999 to 960 and hold 1 hour 30 minutes
Segment 4: Ramp 50 dph to 720 and hold 20 minutes
Off
. . . but I changed Segment 4 to hold 1 hour.



You mean segment 2?

I never use good glass for the first try at a mold. I'm with John above - 1250 shouldn't puddle unless your thermocouple is off or you misread the schedule (I've done that - thought I was firing a fuse when it was a slump - not disastrous but now I always recheck the schedule).
Get some scrap glass and repeat the above schedule making sure you have the hold at 1250 for an hour. Peek in the kiln every 10 minutes after the first 20 until you see the glass bottom out and conform to the cups.
A. W.
Rochester, MN
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Re: Seder Plate Mold Firing Schedule

Postby marykaynitchie » Sat Feb 27, 2010 3:25 pm

Hi Kerry,

So sorry your piece didn't work out! We suspect that your kiln might be running a little hot, but your temperature might be fine. When slumping into an unfamiliar mold, it is important to check the kiln every 10 minutes or so at the high temperature. You can set the hold for an hour, and if you see that it has slumped after 20 minutes, just skip ahead to the next segment of the cycle.

I think that mnglass's advice is good--- to make a fairly small test tile that is the same style(s) and thickness (6mm?) as your original blank but a smaller diameter (like a 6" square). Try a process temperature of 1225 degrees, and check your kiln at process temperature (which is the highest temperature in your programmed cycle), and at regular intervals until you know how long it takes for the blank to slump all the way into one or more of the indentations. Note how much time the slump took at process temperature, skip ahead, and complete the cycle.

That will give you a starting point for your next try at the full dish, but even on the next try, check the piece before the soak is over to verify that it has slumped enough and is not slumping too much, so you know when to go on to the next segment. After you have done this with the same glass styles a few times, you can program and forget it, but if you change glass colors, it pays to check the slump. I hope these responses are helpful. Let us know if you try it again!

Mary Kay
Mary Kay Nitchie
Bullseye Glass Co.

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Re: Seder Plate Mold Firing Schedule

Postby Monika » Mon Mar 01, 2010 2:51 pm

Kerry,
if you haven't seen this post you might want to read it. Should give you some help/hints.
viewtopic.php?f=14&t=206#p715
good luck with your slump, keep it low, extend time not heat, and watch carefully.
Monika
 

Re: Seder Plate Mold Firing Schedule

Postby Kerry7140 » Fri Mar 05, 2010 4:17 pm

Thanks everyone for your input. It is very helpful. As it turns out, my relay stuck on my kiln and it waaaay overheated. I just replaced the Bullseye mold I ruined. I'll follow your suggestions for a test piece before attempting with my new mold.
Kerry7140
 

Re: Seder Plate Mold Firing Schedule

Postby mnglass » Sat Mar 06, 2010 6:06 pm

Kerry7140 wrote:Thanks everyone for your input. It is very helpful. As it turns out, my relay stuck on my kiln and it waaaay overheated. I just replaced the Bullseye mold I ruined. I'll follow your suggestions for a test piece before attempting with my new mold.


Replace the relay too!
A. W.
Rochester, MN
mnglass
 
Posts: 15
Joined: Tue Jan 26, 2010 3:06 pm
Location: Rochester, MN USA


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