'Vermiculite' Vs. 'Fiber Blanket'.
Q: I was wondering if you can tell a big difference in using 'Vermiculite' vs. a
'Fiber Blanket' to cool beads. I just got a 'Fiber Blanket', and am about to try
it. I've had a few beads break in fragile places, using Vermiculite
(example: the lip on the hat on a snow man), and I'm wondering if this will
make a difference. I'd just like to hear other opinions.
A:
If you are making lampworked beads to sell, I strongly suggest you invest in a
kiln. I have purchased many, many lampworked beads from many, many beadmakers
and I can say this - I think ALL beads should be kiln-annealed (after being
flame-annealed), regardless of how big or small they are. Just my 2 cents.
All you lampworkers out there who
are only using a fiber blanket to anneal your
beads - I think you owe it to the buying public to tell us so - up front.
I do anneal ALL my beads, however, I let them cool in 'Vermiculite', remove
them from the mandrel, clean them, and then anneal them. I know I'm a lowly
beginner at this, but in the class I took, we were taught that we could do
it this way, or to put the beads, still on the mandrels in an annealing
oven.
My question was regarding cooling beads down before annealing. As I
understand it, 'Verumiculite', nor a 'Fiber Blanket' will anneal the beads, they
just allow for a gradual cool down so the beads won't break prior to
annealing.
In various industries, large castings of various materials are wrapped with
blanket to slow the cooling rate, which makes the pieces stronger, and I
have some familiarity with this procedure.
The advantages I can think of for blanket wrap over surrounding in
'Vemiculite' would have to do with ease of wrapping over, making sure you had
the beads well surrounded by the 'Vermiculite'. The other advantage of
ceramic fiber would have to do with temperature ratings, but I think you may
be down to about 1400 deg F by that time, and 'Vermiculite' would handle
enough temperature for this application. At this temperature I believe the
heat transfer rate would be close for both products.
The other advantage of ceramic fiber would be that it can withstand higher
temperatures than 'Vermiculite' (some blankets are 1800 deg F, others go as
high as 3000 deg F). This is because of a high Alumina content, which
translates into dollars.
If you find you like blanket wrapping, it may be worthwhile for you to look
into a welding pad, much like a quilted potholder, except made with high temp
fabric, ceramic or high temp fiberglass blanket, and 'Kevlar' thread. Initial
cost would be higher, but it would not shed, and would last a very long
time.
