new question for lampworkers

Pyrex is the same as boro. It's hot glass - the kind that takes quite a bit of heat to work. Boro is done quite a bit because of the different look to it - it can be milky and can change colors drastically. It has a completely different consistency and it cools a lot slower than soft glass (moretti, effetre, lauscha, murano, bullseye, etc.)

vj found this in rec.crafts.beads, from "Kandice Seeber" :

]Pyrex is the same as boro. It's hot glass - the kind that takes quite a bit ]of heat to work. Boro is done quite a bit because of the different look to ]it - it can be milky and can change colors drastically. It has a completely ]different consistency and it cools a lot slower than soft glass (moretti, ]effetre, lauscha, murano, bullseye, etc.)

thanks, doll! i knew you would know!

----------- @vicki [SnuggleWench] (Books)

's not what you take, when you leave this world behind you;it's what you leave behind you when you go. -- Randy Travis

Pyrex is a Corning's brand name for borosilicate glass which uses boron or borax as a flux instead of soda and lime. It has a COE of 37 I think. It's\ the glass that carnival glass blowers make hummingbirds and those spun glass boats and things. Otherwise see Kandice's post.

Yep - I knew someone would have a more technically correct explanation. :) Thanks Louis!

vj found this in rec.crafts.beads, from "Louis Cage" :

]Pyrex is a Corning's brand name for borosilicate glass which uses boron or ]borax as a flux instead of soda and lime. It has a COE of 37 I think. ]It's\ the glass that carnival glass blowers make hummingbirds and those spun ]glass boats and things. ]Otherwise see Kandice's post.

even more info - thanks - i guess i had just never seen it referred to that way and then suddenly ran into a lot of it on Just Beads.

----------- @vicki [SnuggleWench] (Books)

's not what you take, when you leave this world behind you;it's what you leave behind you when you go. -- Randy Travis

And, to add to Louis' post, as I understand it, the much lower COE also means that there are fewer expansion/contraction issues while working (this point more pertinent to bigger, intricate glass sculptures, probably less pertinent to lampwork beadmaking).

I would also assume (can someone confirm) that, just as pyrex is used in scientific and kitchen applications for its strength and resistance to thermal shock, that pyrex/boro beads are also tougher than soft glass (assuming proper annealing in both cases...)

--Dave

scientific and kitchen applications for its strength and resistance to thermal shock, that pyrex/boro beads are also tougher than soft glass (assuming proper annealing in both cases...)<

You would think so, wouldn't you? However, at least with sculptural beads, I have had many more boro beads break than ANY Moretti or other soft glass beads (and I am *not* just talking about Ginger here!). Consequently, I actually steer clear of boro beads, unless they are round. I have been kinda sad to see the huge trend toward boro lately, because sculptural beads are my *thang* and they don't seem to hold up in boro (I especially don't like the pendants that hang from a boro loop). Just my experience and my opinion, of course. :-)

Carol in SLC New pic (9/5):

Are you sure that you are using a Boro annealing schedule?

Does Pyrex also have the color shifting associated boro?

Tina

Roger Parramore showed me a trick on uneven thicknesses of boro. Put the piece in the part of the back flame where the yellow flare just starts to appear. Apparently that is close to where the flame is the annealing temperature of the glass (works for soft glass too). So you can "flame anneal" some of the stress out of the piece without losing shape. Of course, it doesn't replace actual kiln annealing. Hope that helps.

Thanks, Tink.

Tina

Having only the slightest knowledge of lampworking and glassworking I have a question:

Is the annealing temp higher with boro than softer glass? From what I've heard it takes a hotter flame to work with it, so I'm assuming that it takes a hotter temp to anneal as well. Is that correct?

Valerie Website:

Yes. Don't nail me to a tree on this, but I think it is about 1050F. I have to look it up when I (rarely) do boro. May try some beads tho'. Hmmmmmmmmmmmm.

out of boro and

at a workshop

signs of stress.

to get away with

true. When I make

May I ask what you use for a kiln schedule for boro? Please?

- Sandy

Thanks for the info Louis!

Valerie Website:

This answer and link is another one that I forward to myself as email for future reference.

Does Pyrex also have the color shifting associated boro?

Tina>

PYREX is a "brand name" of glass that is borosilicate..... like COKE is to carbonated beverages.

ps - there is no such thing as "color shifting" there is "striking...." which is temperature and oxidization environmental condition affects on the glass while heated - but "color shifting" is a myth perpetuated by the pipe makers. Cheryl of DRAGON BEADS Flameworked beads and glass

Carol - you are probably very correct there for two reasons.

1. Annealing - many people are of the belief that boro need not be annealed as carefully as Moretti -- but this is untrue.
2. borosilicate glasses are STIFFER by nature than soft glasses - they have a stiffer molecular structure, as I understand it - and therefore any sharp impact has the tendency to crack them - especially any 90 degree strike against the glass... A large, solid piece of boro will be significantly HEAVIER and denser than a soft glass - and it has less "expansion" than soft glass. I suspect one can envision that the "expansion" of soft glass is the space available between molecules ... in boro they are closer/denser - in soft farther apart and more able to move apart from each other. So a shock to the denser glass has a bigger and more significant impact than on the 'soft" glass which lets the shock wave travel though it with more flexibility. maybe that's not a very scientific explanation but it's kind of how I understand it. I worked for a person who did those "carvival" pieces years ago - they are NEVER ANNEALED - and with time they do become more fragile and likely to break. glass is glass -it will all break. The nice thing is that a boro piece can be reheated and "healed" or welded back with much more success than a soft glass piece.

Cheryl of DRAGON BEADS Flameworked beads and glass