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Life in the Drug Labs

Glassware Geek

Next year will mark the 25th anniversary of the first chemical reaction I ever did in a research lab. So I’ve been around, but I’m not old enough to remember the days before standard glass fittings. I think you have to go back to the 1950s for that, back to the days of rubber stoppers and hand-bent glass tubing.
Nope, for my entire lab lifetime it’s been standardized glass joints. Those of you in the labs will have hardly given a thought to these, since they’re part of your everyday experience, but I find that nonscientists are often quite taken by these. The joints are just ground glass (the “frosted” look as you’d see in a decorative mug), made to a standard diameter, angle, and length. (Here‘s a flask with some.) They make all flasks, adapters, columns, condensers and what-have-you interchangable, no matter where you bought it. You can assemble anything you feel like assembling, as long as you have the pieces and the patience. It’s like glassware Lego.
Standard taper joints are described by two numbers, like 24/40. The first is the inside diameter of the wide part of the joint, in mm, and the second is the length of the ground glass section down to the other end. 24/40 is pretty much the standard in most organic research labs, except for small glassware, which is 14/20 (you can see by the ratio that that one isn’t as deep a joint.) Most of my work has been done with those two.
Teaching labs, for reasons that are obscure to me, often use 19/22 glassware. I used it as an undergrad, but I haven’t seen any in years, and it would probably look funny to me now. But I should talk: in the last few years, I’ve become a fan of the oddball 29/42 glassware, which (as the number shows) has wider openings than the usual stuff. Big flasks tend to have that size joint on them, but I’ve got all sorts of stuff with it now, in all sorts of sizes.
I like it because it’s easier to get things out of the flask. Scraping stuck powders from the inside walls of a round-bottom flask is something every chemist spends a fair amount of time on, and with these flasks I don’t have to bend a metal spatula to pieces to reach everything. Any working chemist has a collection of metal spatulas that have been tortured into all kinds of shapes to reach up into glassware, but I have fewer than most. Now it’s the 24/40 glassware that looks odd and narrow to me.
Some of you may suspect that I like the 29 glassware because it keeps people from stealing borrowing my stuff. Well, I think that’s how my predecessor in this lab got into it, but I’ve come to enjoy it on its own merits. I encourage my bench-chemist readers to give the size a try. Give your colleagues a chance to smile and shake their heads behind your back, too!

5 comments on “Glassware Geek”

  1. Are there accompanying Keck clips? And what color are they?

  2. allan says:

    19/22? I don’t think I’ve ever seen that. As a lowly undergrad I’ve only ever seen 14/20 and 24/40 with the odd 10/30 for really weird set-ups.

  3. Derek Lowe says:

    The Keck clips (plastic holders that keep the two pieces of glassware from sliding apart, for non-chemists) are red for 29/42. I’m the one-stop shopping mart for those around here, too.

  4. Daniel Newby says:

    That picture page links to a grease supplier whose shipping page says:

    It is also the policy of SPI to not make shipments to residential addresses out of concern that dangerous items could fall into the hands of children. A style #5 tweezer could be just as deadly as a broken vial of osmium tetroxide in the hands of child.


  5. schinderhannes says:

    Hi Derek
    I´ve been reading your blog for quite some time – good fun to read! so this is the first time I comment (as you can notice I am a colleague of yours…)
    One comment to the joint: in Germany 24 is nearly unknown, we only have 29s. In university we had 14s to go with it, but my current lab it is also a lot of 19s.
    All rotavaps (buchis) over here have 29s.
    So good for you to discover the best joint size there is!

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