Glass Message Board
Glass Identification - Post here for all ID requests => Glass Animals & Figurines => Topic started by: Borolamper on January 25, 2007, 10:37:15 PM
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I joined to use the classifieds, so I thought I would try to make myself usefull.
I have read a great deal about glass over the years, including every fusion magasine (The American Scientific Glassblowers Society journal) from June of 1956 to November of 2002 inclusive. While my focus has been learning about borosilicate, I might have an answer for your oddball question.
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Much appreciated, here is a good one for starters that I never get round to finding out myself:
Why is Borosilicate glass the choice of lampworkers/flameworkers?
My intro to glass was handblown art glass resulting in ysartglass.com and from there the parent company that developed one of the eariler succesful borosilicate glasses for use as gauge glasses:
http://www.ysartglass.com/Indexart02.htm
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A low coefficient of expansion (C.O.E.) makes borosilicate less prone to heat stress. Soda-lime glasses tend to crack much more easily in the flame, but they allow for a much larger colour selection, as it is worked at a lower temperature.
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Thanks, leads to more q's... so do some people work with soda-lime mixtures instead? I know you cannot mix them due to different COE's.
Is there any easy way of distinguishing the type of glass used?
When did coloured forms of borosilicate become available?
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Most beadmakers work soft glass. Moretti is an example.
Assuming you are looking at a finished piece, and not at raw material you can do compatibility test with in the flame, the simplest way to distinguish between hard and soft glass is by density. Soft glass weighs 1/3 more, or hard glass weighs 1/4 less, depending on which one is considered normal. Simplest way in the flame is to take a small piece of a known glass, and an equal piece of the unknown glass, and make a blob with them overlapping. Pull this out into a thread, and watch how much it curves as it cools.
Cobalt blue has been around in limited quantities for quite some time, but generally speaking, early to mid 90's was when borosilicate colours became available. I was mixing my own colours when I started back in '93.
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Very useful, so all of the older stuff will be soda lime? i.e. http://www.ysartglass.com/Pirelli/Pirellianimals1.htm
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Yes, those look like soft glass colours to my eye, even ignoring the dates. No reduction of the transparent greens (in boro, copper dioxide transforms to copper oxide on the surface unless silly amounts of oxygen are used, giving it a reddish skin or streaks). The opaque yellows and oranges (cadmium) have only become available in boro in the past few years, and are prone to boiling.
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That is extrermely useful as the popularity of lampwork figures is growing and this will make it easier to separate the older from some of the new. Won't help where soda lime glass is used but it does at least help in dating etcetera.
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Is cadmium still being used then? I thought this was a real no-no, being so harmful.
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Sealed inside the glass it is safe enough.
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Sealed inside the glass it is safe enough.
I wasn't planning to suck it anyway ;D
Seriously, I was under the impression that cadmium was banned from industrial usage and was stopped being used in glass around 1965. I was alluding to the harmful nature as a raw chemical, rather than its state within the glass, which I knew was harmless.
Thanks.
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Here is Glass Alchemy's user manual. Look about half way down the page for what they call "crayon" colours.
http://www.glassalchemyarts.com/support/user-manual-pg1.html
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Their Health & Safety pages seem to give good details of the risks of working with the various compounds. Fascinating reading, I wonder how much below average glassmakers lifespan has been over the years! Particularly when some of the lauded achievments of using such componds only recall the companies or originators and not the poor sods who were killed early by having to work with them.
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Henry Grimmett knows his stuff, for sure.
I have heard somewhere (quite likley untrue) that glassblowers traditionally have had the third shortest life expectancy for health reasons of any occupation, next only to uranium and coal miners.
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Than again, it was quite surprising how long some lived - the history of Chance Brothers reveals some living into their 80s and this was on a diet of many pints of beer a day to prevent dehydration!
There is also a report of one engineer having a working career of 71 years at Chance... sheesh...
New Health & Safety Regulations:
1. Drink More Beer!
2. Blow, don't suck!
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The bell curve of statistics needs such exceptions or the science would collapse, but it is pure Chance as to who gets lucky. Perhaps, something in a name after all.