Quick annealing??

[Bijoux]

Hi everyone. Hope you can give me some opinions here. Usually I anneal my beads overnight through a typical annealing cycle( McKinney toolbox kiln with digital controller) and take them out in the morning at which time they are at room temperature. I have a show coming up and am trying to get beads out of the kiln as quickly as possible. So here is my question... After they have gone through the annealing cycle, and are below the strain point and the kiln is off, how hot can they be and still be safely removed from the kiln? My studio is really well insulated and it takes hours for temp to drop from 550 to under 100 degrees. Could I take them out at 200 degrees? or 150? and maybe transfer to a towel or something? What do you think? Thanks, Ann "Bijoux"

[suzanne]

I don't think it's smart to take them out when they are above room temperature, you have gone through all the effords to take the stress out of the glass, but I think ( someone who really knows for sure please chime in) when you take out the beads that hot, you are bringing the stress right back in

Suzanne

[Bijoux]

Hi Suzanne, thanks for answering. That is my gut feeling too and I never have taken them out early but tonight, after running out to my studio for the tenth time to check temp, I was unloading the dishwasher while the dishes were still hot. I was taking wine glasses out that were so hot I was cussing as I put them away ..but it got me wondering just how hot was too hot and just how quickly could you cool down annealed glass . Ann "Bijoux"

[Kaibeads]

I think you could safely take them out at 300, but they would be pretty hot to handle.. 300 degrees is way below the strain point, so I don't see how stress could be introduced at that temperature.

[suzanne]

Well I figure that at the moment you take beads out to room temp at a high temperature, you cause thermal shock, and therefor create stress in a bead. Like I said, I do not know this for sure, but it sounds logical to me:)

Suzanne

[MikeAurelius]

Take them out at 400 and put them into a bead blanket to cool the rest of the way.

[pam]

You can't introduce stress into glass below the strain point, however thermal shock is a great possibility. For soft glass I wouldn't remove them above 200, but I have seen people take them out at 500. It really depends on how brave you are and what you are willing to risk!!
Pam

[suzanne]

But isn't thermal shock caused by stress?? I'll take the safe side and just let the beads cool:)

[Mr. Smiley]

Thermal shock is caused by stress, but below the strain point, it is only temporary. Soft glass needs to be 200 or below to be safely removed from the kiln. The problem with taking them out sooner is... hairline cracks that you may not catch. Some may break in half and you wouldn't sell those... but what about the beads that you don't know are compromised? Better to be safe than sorry. :D

I would still use warm vermiculite or warm fiber blanket to cool at 200 with soft glass... or just open the kiln door and speed up the cooling a bit.

[JavaGirlBT]

or just open the kiln door and speed up the cooling a bit.

This is what I do once the kiln is at 300 or less. I just use a ceramic kiln stand to prop open the door.

[Bijoux]

Thanks so much everyone. That is exactly the information I wanted to know!!
Ann "Bijoux"

[Moth]

I agree with Brent 100%.