annealing on regular shelf in fiber kiln

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ruthelf1030
Posts: 17
Joined: Mon Jan 05, 2004 3:15 pm
Location: Melrose, MN

annealing on regular shelf in fiber kiln

Post by ruthelf1030 »

Hi all,
I just read a 3 p. thread about annealing in a fiber vs. brick kiln fusing
pattern bars. Well, I just got a Sierra fiber kiln w/fiber shelf and fiber kiln posts. I had been fusing in a fiber kiln with a standard shelf - don't know what it is made of. The point of the thread seemed to be that there might be annealing concerns all the way down to around 400 F. in a fiber kiln.
Would not a regular shelf which I assume holds more heat on the way down, change the annealing situations involving thicker larger pieces of glass. Also,
I got this kiln because my supplier sent me the pattern bar maker saying it would fit in my 6 inch fiber kiln. It does not and I refuse to cut it up.
I don't want to use my large kiln for this small bar maker or for experimenting with small bar projects.
I have had annealing problems in fiber kilns before and now I wonder if the regular shelf vs. a less heat holding fiber board shelf is the problem in a fiber kiln.
Could not find out what regular kiln shelves are made of - I thought they were clay. My 5 inch tiles tend to crack on the way down.
The elements in this sierra are imbedded -not seen, on 3 sides. The inside is 8 x 8 x 6 tall, the fiber shelf is 1/2 thick, and my regular shelves are 1/2 inch thick and my kiln posts are 1/2 inch. I noted the annealing times for BE opague mixed with clear - 990 possibly all the way down to 400.
Any ideas?
Regards and thanks, Ruth
Still in central Minnesota
elin
Posts: 20
Joined: Tue Oct 07, 2003 11:11 pm
Location: portland, or
Contact:

Post by elin »

Hi Ruth,

I might be able to help answer some of your questions.
Regular kiln shelves tend to be made of mullite. Using this type of shelf might help hold more heat-- and a thicker one-- like 5/8"+ would probably hold even more heat.

I am a little unclear about your annealing/cracking issues-- can't you adjust your ramp-down time, regardless of fiber or brick/mullite materials? &/OR, prolong the soak at the glass' strain point?

And, I don't know what pattern bars are... but cutting a fiber shelf is pretty easy-- it's just a matter of being safe with the fiber.

Anyway, we build small fiber kilns with brick hearths, and we sell mullite shelves to go in them for fusing. It seems to work for our kilns...
So, I hope I have helped a little.

Good luck!
-elin
http://www.ekmillerco.com
ruthelf1030
Posts: 17
Joined: Mon Jan 05, 2004 3:15 pm
Location: Melrose, MN

Post by ruthelf1030 »

Hi Elin,
Thank you for your reply.
Not sure what mullite is, but I have access to clay and a ceramic kiln
and thought of making a few shelves. Possible?
I am still learning the Sierra controller. It is preset for PMC3, PMC standard and PMC+, and then only one 4 (four) segment free to program
yourself selection.
I would have to figure out how to ramp up to 1500 F and hold until the
pattern bars in their mold are well melted, and then flash cool, then down
to 990F and hold, then at slow cool down to around 450 or so but either
50 or 100 degrees F per hour. ALL in four stages. Glass is BE clear & opaque and Wasser. 90 COE and CBS Dichro.
Maybe someone out there has a Sierra who has figured out how to do this?
Pattern bars are something I have been making with dams for some years.
I now have a mold for them - slots that a person can layer frit, broken pieces or strips of 90 COE or compatible glass into and get a nice bar of different colors which I then cut with a tile cutter or nippers (mine are thin).
Hope to get a saw this year for larger pattern bars. Does that make sense.
Sierra is made by Champion and I cannot find a site on line for them.
Never used a controller before either.
Any help is much appreciated!
elin
Posts: 20
Joined: Tue Oct 07, 2003 11:11 pm
Location: portland, or
Contact:

Post by elin »

Ahhh, I understand pattern bars now... OK.
Mullite shelves are available at ceramic supply stores-- it's better than just any kind of ceramic material, because it is a refactory material but I am not really sure of the details... You may very well be able to make shelves yourself out of some kind of high-temp clay.... maybe somone else will know more...
I'm pretty sure that PMC Supply sells those kilns, so they may have more info or a link to the manufacturer. Do you have a set point on your controller, as well as the 4 4-step programs? If so, you may have some options for your fusing program... Otherwise, I would just use a really slow ramp-down. I don't know if that will help or not...
Good luck!
-elin
ruthelf1030
Posts: 17
Joined: Mon Jan 05, 2004 3:15 pm
Location: Melrose, MN

Post by ruthelf1030 »

Hi again,
Thanks for the quick reply.
The first 3 programs, the ramp Speed is set and not variable.
But, the other two factors, hold temperature and hold time, can be
altered.
So, the PMC Plus on the first program is altered to 1110 F by myself
so I may cross over Dichroic cabs with PMC clay syringe silver over
the cab without cracking the cab.
That program was full ramp to 1650 and hold 10 minutes, and the kiln
goes off and just cools.
The second is to 1470, slo ramp of 1500 F per hour (I think that is fast),
1470 F for 30 minutes where a person has brass, glass and ceramics.
The third rungs full ramp to 1650 F and holds for 2 hours.
The fourth program lets you choose ramp speed, hold temp and hold time.
My directions are for the brand new 8 segment.
Mine is for the 1 year or older 4 segment.
My directions don't explain how to ramp down, or it is something I just
don't get (senior moment or controller challenged I guess).
I was told I cannot break this thing. I hope so. I have kiln washed
the base and burned out the fiber board and kiln washed that.
Now, did you say you sell mullite boards. Did I misunderstand.
My fiber board exactly matches the bottom of the kiln, but I thought
the board was supposed to be about 1/2 inch smaller all around.
Oh whoa is me - The 4th segment has me baffled.
Thanks again,
Regards,
Ruth
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