Use a kiln to hold heat for later batch annealing -- as opposed to fiber blanket?

Jammy · #1 2012-01-02, 1:15pm

I have a jen ken fire brick kiln with an infinite switch, and I think the pyrometer is off.
I'm ordering a new pyrometer next week, but in the meantime since I don't have a fiber blanket (I've never batch annealed before) I would like to use the kiln as I would a fiber blanket. Use it to hold the heat in the beads until I can batch anneal them later.
Is this ok? Most of my beads are less than 1 inch in diameter, but some of them are longer bicones or barrels. I would say about 2 inches in length and about an inch in diameter (pretty thick).
Will these be ok in this type of environment. I know they won't be annealed since the pyro is off by probably 100-200 degrees, but about what temp can they be held in the kiln for at least a couple of hours, then gradually ramp down to room temp and still be ok until I can batch anneal them? Are they more or less likely to crack using this method, as opposed to holding them in a fiber blanket? I would think this way would make them less prone to crack, as long as they are properly batch annealed later.

ALSO, is it ok to batch anneal raised decoration -- as long as it didn't pop off the first time around? I can handle them popping off in the kiln....what I can't handle is them popping off after I give them away or put them in jewelry.

Alaska · #2 2012-01-02, 2:19pm

A fiber blanket will help to slow down cooling but is no substitute for annealing. Some beads will crack when using a fiber blanket.

Many lampworker garage their beads for the day in a kiln. Then anneal at the end of the day. Others choose to batch anneal every week or two depending on how many beads it takes to fill up the kiln.

Batch annealing is more efficient from the standpoint of the electric bill. But there is generally a higher loss due to thermal cracking.

Jammy · #3 2012-01-02, 2:35pm

Thanks Alaska. What is the lowest temperature I can "garage" them? I was thinking that "garaging" the beads in the kiln -- then annealing them maybe 2 weeks later would be okay.

jaci · #4 2012-01-02, 3:34pm

I was thinking maybe 650 -750 would work. The kiln would have enough heat to keep most of any small pieces from popping off and have enough heat for the bricks to hold some heat when you turn if off. Then run them through a full cycle later

Jammy · #5 2012-01-02, 3:39pm

THANK YOU Jaci!

I just read somewhere that if you hold them above the strain point (850F) then slowly ramp down they'll be ok to anneal later.

jaci · #6 2012-01-02, 3:45pm

Really a fiber blanket will not hold them any higher than 650 I don't think, so you are better off in the kiln for a while. It was a great idea on your part. I would do the same.

If you are holding them above the strain point and ramping down that IS annealing

jaci · #7 2012-01-02, 3:51pm

You can test your pyrometer. Put a rod of glass propped up on something on both ends (like a rod holder, or those mini terracotta pots from the craft store) and turn it up. It should slump at about 1100 (1140 I think) if you think your temp is high start around 800-900. If you think it's low start higher. When you find a temp that the rod bends in the middle that is about 1100.

Jammy · #8 2012-01-02, 6:12pm

Quote:

Originally Posted by jaci

You can test your pyrometer. Put a rod of glass propped up on something on both ends (like a rod holder, or those mini terracotta pots from the craft store) and turn it up. It should slump at about 1100 (1140 I think) if you think your temp is high start around 800-900. If you think it's low start higher. When you find a temp that the rod bends in the middle that is about 1100.

This is another test I can use.....so far I have three. There is the paper test (paper will incinerate at 451F), the penny test (pennies newer than 1982 series will slump at 787F), and this one.

jaci · #9 2012-01-02, 9:31pm

If your pyrometer is truly off, it may show staggared tempatures and larger difference at higher temps. If its just the read out or position of the reader, the temp may be off the same number of degrees consistently. that could be easy to change (or even just keep a mental note of, ok and written too!!) I would do all these tests on the way up to temp to see

! It's quite the science project lol!

(now I want to slump pennies for fun!!!

)

rdbeads · #10 2012-01-03, 6:22pm

I garage my beads at 750 every time I make beads. I batch anneal because I can only make beads twice a week. I usually batch once every couple of months and almost never lose any beads from stress.

houptdavid · #11 2012-01-03, 6:39pm

Why not solve the problem?

http://jenkenkilns.com/af3p-remote120volt-15amps.aspx

Alaska · #12 2012-01-03, 6:41pm

Or make your own for a third of the price with a Fuji PXR-3 controller and a SSR.

Judy D. · #13 2012-01-08, 1:57pm

"Or make your own for a third of the price with a Fuji PXR-3 controller and a SSR."

Alaska, can you please post very explicit directions and sources for whatever equipment, supplies and processes are needed to do that? I'm a beginner; purchased a nice little kiln with a pyrometer but no controller on eBay, before realizing how inconvenient it would be. I would LOVE to get/make a controller for way less than the prices I'm seeing as I look around online.

If this is already posted somewhere, do you have a link/links? This would be a HUGE help to me, and probably to many others...Thanks!

Judy

28676bhe · #14 2012-01-08, 3:08pm

http://www.harborfreight.com/non-con...ter-96451.html
This has helped me determine if I am at least in the correct range to garage the beads I'm making - my kiln just has an analog reader, and I don't feel it is reliable.

I'm just using a regular 8" square kiln with a lidded top that has a stay cool handle. I had two stainless steel corners made for it so that the mandrels, when I put the beads in diagonally, will not touch the elements (2.5 x 5 inches, softly bent at a 45 degree angle). This covers the bottom row of elements and doesn't seem to affect the heat.

Then I clean them and batch anneal according to the glass used (104, 90, 96, etc).

I'm breaking a few here and there, but that's my fault. So far, this system is working well for me.

Oh, and the temperature thingy doesn't go above 1000 degrees, so when you see it reading 009 degrees, that is really 1009. But it's cheap!

Barbara