Sciencemadness Discussion Board

Ground glass stoppers

elementcollector1 - 31-12-2012 at 21:51

First, I have a 14/20 'adapter' of sorts which consists of a male joint, a short 2" glass tube, and a lip at the other end. I have no idea what it's used for (I put them to work in all sorts of random applications), but it so happens that I have an extra. Is there any advice for making a good stopper from this? I would imagine that by heating the glass up, taking hold of the top molten part with a good pair of pliers and twisting, the end would seal itself much like how an ampoule is supposed to seal itself.

Second, how do you produce a stopper from scrap glass? Can I make a mold with clay, and melt some glass into that? How would I get a perfect stopper from the joint?

This could prove useful for recycling instances of broken glass and such.

Siggebo - 1-1-2013 at 06:00

One of these? In that case it's a tube adapter. I imagine the easiest way to make a stopper out of it would be to attach a short length of tube and clamp it tight.

[Edited on 2013-1-1 by Siggebo]

kavu - 1-1-2013 at 07:27

Ground glass stoppers are rather tricky to make and require a lathe to get the taper correct. It's much easier to just buy stoppers online.

Endimion17 - 1-1-2013 at 08:07

Stoppers are made by robots. Rarely any flameworker makes them at workshop using a lathe.
Don't even bother. Just buy the damn things.
Happy New Year. :)

smaerd - 1-1-2013 at 08:20

You could buy a length of teflon rod. Use a sanding attachment on a drill-press to get the appropriate taper, hack-saw off a bit above the taper you made and use that. I've had a similar issue with finding a 10/30 stopper at a reasonable price and that's what I plan to do, then again it's sensible for me as I already have teflon rod sitting around.

elementcollector1 - 1-1-2013 at 10:38

More like these with a lip on the end...

[Edited on 1-1-2013 by elementcollector1]

TheChemINC - 1-1-2013 at 16:37

maybe it is used as some sort of drying tube? or i have seen peices like that that have a little pouring spout on them so it is easier to pour liquids out of the flask.

although, your does have a longer neck.... but you could probably heat up on side of it until the glass is soft, and then using a very hot nail or metal rod, form a little spout on it. i would think that hiving something like it would be very useful.

i hate when i pour things out of flasks and they run down the sides! :P

kavu - 1-1-2013 at 16:58

That kind of glassware is used by glass blowers when making custom apparatus or fixing broken ones. Long tube can be cut to derised length and melted to glassware. Simple way of intoducing ground joints without too much hassel.

Texium - 10-8-2014 at 15:15

Does anybody have any extra ground glass stoppers that they'd be willing to sell or trade? I need a 29/42 stopper for this nice Pyrex storage bottle that I have that has a ground glass opening, but didn't have a stopper with it when I got it. I'd also be interested in smaller stoppers for small flasks, of sizes like 22, 19, 16, 13, and 9.