SuperOxide
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How to tell borosilicate from non-borosilicate glass
I have a pretty decent amount of glassware, a lot of it I buy from Biotech Bargans and they buy it from colleges or companies that have labs and are
shutting down or getting rid of excess glassware. A lot of what I get is Pyrex, Chemglass, Ace, Laboy, etc. And I try to steer clear of anything
that's soda-lime. I know the difference between PYREX and pyrex. And according to this article, you can tell the difference between borosilicate and soda-lime by the color of the edges:
| Quote: | | If you have a dish at home that you want to test you can also try just looking at the hue. If you look at the edge of a dish and it is made out of
soda-lime glass it will be a blueish-green hue. If the glass is Borosilicate then you should not see any color. |
So this was my quick test that I would use, but the problem is - A lot of the PYREX stuff I have (some of it was new, some used) has that green color.
And I tested some of this by cranking my hotplate up to pretty high temperatures and then putting the glassware on it, filled with cold water to see
if it would break (as well as some other tests that break things like salsa jars pretty easily), and I haven't had any of them break.
I've never had any of these break or crack during any experiments/synthesis I've done, and I have definitely abused some of it quite a bit.
I posted some pictures to an Imgur album and put captions to each one. https://imgur.com/a/XEUXJB7
Im hoping someone can make some of these make sense. I could maybe believe that some of my Pyrex is fake, but all of it? No way. Some of it is from
Germany, some from BiotechBargans, some from other sellers.
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Twospoons
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The green tint is from traces of iron in the glass. No reason why borosilicate couldn't have that too. I know you can get iron free soda-glass ( its
just costs more), so it would not have that tint.
Borosilicate should be harder than soda, so there is always the scratch test.
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Chemetix
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All the glassware you have is borosilicate. There is practically no one making soda glass beaker like the ones you have. The decals seem like older
Kimble glass at least on one item that I can make out, but that's circumstantial.
Really, the only scientific glass that commonly isn't borosilicate is burette or other volumetric ware. It's termed AR glass which is a type of soda.
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SuperOxide
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Quote: Originally posted by Twospoons  | The green tint is from traces of iron in the glass. No reason why borosilicate couldn't have that too. I know you can get iron free soda-glass ( its
just costs more), so it would not have that tint.
Borosilicate should be harder than soda, so there is always the scratch test. |
I see, that makes total sense. Thanks!
| Quote: Originally posted by Chemetix | | All the glassware you have is borosilicate. There is practically no one making soda glass beaker like the ones you have. The decals seem like older
Kimble glass at least on one item that I can make out, but that's circumstantial. |
Right, but it's not like that doesn't happen. For example, I think in that Life After Detonation thread he said he was using a "Pyrox"
soda-lime beaker without realizing it.
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Tsjerk
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You can easily test what you have by boiling some water in the beaker and cooling that in an ice bath. Soda lime can't handle anything more than 30 -
40 degrees heat gradient over a certain distance. This gradient you can easily reach with boiling and freezing water while borosilicate should easily
handle these gradients when not thick vacuum glass or something.
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unionised
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I think Pyrex cookware is available in a range of colours.
The traditional way to tell soda glass from borosilicate was by refractive index.
Pyrex "disappears" in glycerine.
Not very useful if you are looking at a whole beaker, but handy if you are glassblowing and have lots of tune + rod.
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Dr.Bob
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I have seen borosilicate with clear, green, blue green and other tints, as stated, it is the iron content, which does not change the temperature
stability. There are a few simple density and refractive index tests for boro verses soda lime, but almost all lab glass is boro. I'd guess there
is some way to see with a UV-VIS or some other simple test, but rarely done.
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Twospoons
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Reading around I found the density and refractive index ranges for boro and soda overlap. Only distinctive diff I could find was hardness : 7 for
boro, 6 for soda
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yobbo II
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Soda glass will fluoress under UV light a bit.
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SuperOxide
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I think what Twospoons and Chemetix mentioned is pretty convincing. The color is just from some iron contamination (which when I Google it, seems
pretty accurate), and it would be very unlikely that anyone make such glassware in soda-lime, especially the 4 and 6L erlenmeyer flasks.
I was just being paranoid... lol
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Texium
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I think the color thing is a common misconception that has developed because most borosilicate lab ware is colorless, whereas most soda lime glass has
a green tint. Really it’s a correlation-not-causation situation. It’s more likely that higher value borosilicate glass destined for lab ware will
use higher quality ingredients with fewer impurities. Thus, no color.
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