Funkerman23 - 13-1-2012 at 19:54
On this post I am talking about Jointed labglass. as I make most of what I need or can't buy I had scrounged & saved until I bought a used 19/22
Pyrex organic lab kit.I was told that pyrex brand glass would stand the abuse of the home chemist.. but when I got it I noticed a few things that
worry me so I have come here to ask: when buying jointed lab glass what are the key things to look for/ avoid? I have some Wheaton clear seal glass
that hasn't a single bubble anywhere but the Pyrex claisen adapter has some in the arm's seam. and as far as inspecting the ground surface what are
the key things? Is there a gauge of some kind?
zoombafu - 13-1-2012 at 20:42
The only way to tell if it is good is to actually use it. Set it up, pull a vacuum on it, heat it, etc.
Pulverulescent - 14-1-2012 at 04:19
And put a respectable distance between the glass and your good self!?! 
P
Arthur Dent - 14-1-2012 at 06:59
@Funkerman23 : Good question, Pyrex brand labware isn't like the kitchen-grade pots and vessels used in cooking where pretty much anyone can use the
word Pyrex, the Pyrex brand labware still carries a high level of quality and specs. Stuff like Kimax, Buschi, Pyrex, Adams & Chittenden, Ace
Glassware and the likes are good enough for high-end lab use.
Don,t worry too much about bubbles and inclusions in glassware, I have some really high-end stuff that does have some tiny bubbles and it doesn't
affect their operation.
Then there's the stuff that comes from India and China, it's still pretty good for general use but there might be imperfections, like that RBF that I
have where the neck is so distorted that a regular rubber stopper barely fits, or that beaker that I ordered brand new with deep scratches on it!
Things to avoid in the used department is scratches, chips, alkali corrosion. a small chip on the tip of a condenser is nothing to worry about, but a
small chip at the bottom of a RBF could be catastrophic. Also small "star shaped" cracks that are sometimes very tiny, but can have heavy consequences
with a beaker filled with boiling acid! It also depends on the type of vacuum you'll have, a small water aspirator is less likely to shatter weak
glassware than a heavy duty lab vacuum pump.
The ground joints should be smooth and when you connect them together without grease, should rotate freely all around without any jams. Always use
proper silicon vacuum grease or Glindenmann rings.
As the previous posts mentioned, try out your new gear in real life with simple boiling water setup and basic vacuum (water aspirator). If it passes
the test, then you can use it for regular lab use.
Robert
[Edited on 14-1-2012 by Arthur Dent]