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-   -   vermiculite vs. kiln (http://www.lampworketc.com/forums/showthread.php?t=313472)

rarneyjr14 2020-02-11 12:25pm

vermiculite vs. kiln
 
I am new to this site and have been reading the thread on annealing with vermiculite. It says you can anneal your beads using vermiculite until you need to group anneal and then you need to use a kiln. I am a little fuzzy on this group annealing process. Any help will be greatly appreciated

Eileen 2020-02-11 3:28pm

You cannot actually "anneal them", but you can slow the cooling process enough that smallish beads without thin pieces sticking out can often make it whole through the cooling, so that they can be annealed later.

Larger beads and ones with protrusions that will cool at a quite different rate as the main bead are more likely to crack. Also, some glass is more prone to cracking than others if not put immediately into a kiln.

There are also cooling bubbles that work similarly to vermiculite but are cleaner and some say work better, and there are also fiber blankets made to keep the heat for an extended time.

You can anneal later "batch anneal" by putting the cool beads in a cold kiln and bringing the temperature up in a controlled manner, and going through the controlled hold and cool down phases to actually anneal.

rainygrrl 2020-02-12 10:49am

To add to Eileen's great explanation...

The cooling bubbles are erroneously sometimes called "annealing bubbles." I like them better than vermiculite, but the cost is higher and they need to be ordered online.

Also, I keep my bubbles in an old crock pot set to high, to help improve chances of the beads surviving until they can be annealed.

For any of these temporary methods, be sure to keep a new hot bead away from others that are already cooling. If they touch and there's too much difference in temp, the cooler one will crack.

Eileen 2020-02-12 11:00am

Good points Roberta!

losthelm 2020-03-01 5:12pm

That's a good question. often the terms can be mixed around depending on the user. Bubbles, fiber blanket, or vermiculite helps reduce the internal stress some but isn't enough to remove all of it so over time things are much more likely to break :(

You may have someone in your area able to batch anneal for you once you have a bunch ready. In general the community is friendly and supportive willing to help new lampworkers out. Some teaching studios will have a kiln setup to anneal and ship pieces after a session or hold on to things until you can pick them up the next day.

Frit Diva 2020-03-02 4:46pm

When I was first starting out, I used an old deep fryer and filled it with vermiculite. Set it on the highest setting (which I figured was somewhat hotter than a crockpot). Used it for a while, but when I started making things I really liked, I quickly made it a priority to purchase a kiln.
A digital kiln is of course preferable, but you can also anneal in any kiln that has a stepless controller, and later add a digital kiln minder (controller). Using a manual (stepless) kiln requires about an hour and a half of minding the kiln temperature after you are done working for the day and you will have to do some experimenting to learn how your kiln works. I used a manual kiln for the first 10 or 12 years that I did glass and had no problems.


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