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[Enamel Bits] Glass question


#1

All the info on orchid lately about glass has moved me to ask a
few questions about the medium. I am interseted in knowing if
the tips John Burgess made about discoloring are applicable to
lampworked beads, marbles, etc. I am using a premix, natural
gas/ compressed air torch with a “rosebud” type tip. I have
3/8" softglass rods (clear, yellow, white, and green) which
should have a co-eff. of 97 or so. when I heat the glass I’ve
been tring to use as hot of a flame as possible because the
overall time it takes me to get the glass into a workable state
seems to be rather lengthy (3-5 min.), even with a fairly large
flame (3-6 inches long). All my glass that I work with becomes
very discolored, even the clear turns a metalic greyblack.

The tip I’m using is a medium size aprox. 3/4" in diameter,
should I move to a larger one? Also, I’ve been flame annealing
all my work with limited success. I have access to a nice
computer controled electric kiln, but I’m not sure it would
work. The heating cycles that I’ve found in books for annealing
small pieces of glass (1/2" thick and less) requires a very rapid
heating stage that it couldn’t quite pull off in the time
allowed. Is this a major problem? and is there a problem with
cooling it from the soaking temp too slowly?

I would have asked this on the Glass Line disscussion list but

every time I’ve tried to subscribe there has been an error (My
experiance with Orchid has proved to be far more reliable). The
best way to learn this would be to have some one show me first
hand. I’m just try’n to teach myself out of pure lack of
funding for a “proper” education. My teacher knows alot about
metals but he hasn’t been able to help me much with glass. I’
doing an independant study so I guess I can’t ask for too much
help. : )

Thanks for any help,
Jeff Cleveland aka JevFro
1609 N. Water St.
Ellensburg, Washington 98926
JevFro@hotmail.com
http://www.cwu.edu./~clevelaj


#2

From what I have read in books (Cindy Jenkins) or have gleaned
from others (my class got cancelled) MAPP gas is used for the
rods. MAPP is hotter that propane. Your rods sound like bullsye
or uroboros glass which have coe’s of abt 90 as opposed to
Effetre or Moretti glass which is softer and has a higher COE
(rate of time over which it must cool). The lower the COE, the
less fragile the glass (Ithink). Bullseye is gaining popularity
because it is made in the USA, as opposed to Italy, therefore it
is cheaper and its lower COE makes it Easier? I’m not sure. The
Moretti and Effetre are the same. Effetre has taken over Moretti,
or vicey versey. Moretti has been around a long time and has a
great and beautiful tradition. Bullseye is new and is getting
more colors all the time.

However, if you are making beads 1/2" or less you can cool them
down in a tin can full of vermicelli (Please don’t laugh if I
mean vermacetti.) Anyway, the stuff you can get at a garden
supply. Or you can tuck them into a ceramic fiber blanket.
Arrow Springs - Home Page at http://www.el-dorado.ca.us/~flameon/

has a good online catalog for glass stuff. The glass people use
an oxidizing flame,: more air to fuel, and metal people like a
reducing flame : more fuel to air because oxidizing flames
cause firescale on metal. Conversely, a reducing flame is too
cool for glass and tends to discolor it.

Feel free, everyone, to correct me if I am wrong. I am a
grasshopper. I have read more that I have done. Am I clear, and
am I correct?

Maggie M


#3
vermicelli (Please don't laugh if I mean vermacetti.)  

Sorry, I had to laugh. Vermicelli is spagetti! I think you meant
vermiculite. I recommend to all of you interested in beads that
you find your way to the AOL bead boards. The people there are
knowledgeable, and more than happy to share what they know! Re:
Moretti vs Bullseye, I think the thing there is that Bullseye
doesn’t have the color intensity of the Moretti, and I don’t
believe the designs come out as “crisp looking” as they do with
Moretti. Here is a link for you AOL members to the boards where
the bead people lurk. Oddly, there are few silversmiths to be
found here- go figure. Anne


#4

Well, you’re almost right, Maggie. However: most beadmakers
don’t use MAPP gas. (Check out Cindy Jenkins’ second book “Making
Glass Beads”. I recommend it for those of youinterested in
beadmaking: gives a thorough explanation of the glass, tools, and
process.) Sometimes people starting out will use it to see if
beadmaking is for them, but those who are serious in the endeavor
use a propane/oxygen torch or burner. Soft glass folks use a
bench burner with a “surface mix” (much more oxidizing, less
discoloration, hotter); pyrex folks usually prefer a pre-mix
torch. You’re right about why metalworkers prefer a more reducing
atmosphere than glass workers. Reduction inhibits oxide formation
on metal, but facilitates discoloration in soft glass.

About Moretti (Effetre) vs Bullseye, most of us use Moretti, I
think. Much cheaper, even though it’s imported, because Bullseye
just isn’t up to speed with making the stuff in quantity. ($9/lb
vs. $25/lb - big difference!) Bullseye isn’t “new”; they’ve
been making sheet glass for the stained glass industry for
decades, and they are big producers of glass for glass casters
and kiln-workers. But the rods are a new thing in their line.
Because of its COE, it is iffy-compatible with glassblowers
colors and frits so that’s why some people like it. However, its
lower COE (coefficient of expansion) does not make it less
"fragile", nor does it affect the “rate of time over which it
must cool”. It is just a measurement of the rate at which a glass
expands/contracts at a particular temperature. Generally, lower
COE glasses are stiffer to work and melt at higher temperatures.
It’s a number glassworkers file away because it tells them
whether glasses are compatible with each other.

You can vermiculate-cool beads of any size if you’re careful.
Preheat the vermiculite on a hot plate, and keep it hot as you
work. Best to insulate the can it’s in with some fiber blanket or
something. Turn off the hot plate when done and let beads
completely cool before removing. You will still need to anneal
them in a kiln to have them be completely annealed.

Hope this helps.
Rene