Sciencemadness Discussion Board

Ground glass joints (ball vs taper)

Duster - 21-6-2016 at 18:38

Hey guy,
Just curious what people's thoughts are on ball joints vs taper joints. I have a good bit of 24/40 glassware, eventually I'm at least going to get a complete simple distillation setup in 14/20 for small amounts, but that's another story.

Any big pluses for ball joints? I know 24/40 is cheaper,and more common, but the price difference isn't huge and I've found everything I could need glassware wise in both 24/40 and 35/25 joints.

I know, or heard rather, that ball joints tolerate misalignment better, accommodate thermal expansion between dissimilar materials better, and maybe easier to clean (or at least not freeze together).

Basically, aside from the obvious "stick with 24/40" (since that would be the smart thing to do), is there any compelling reason not to get some 35/25 ball joint glassware?

Praxichys - 22-6-2016 at 04:39

Just curious - where are you getting 35/25 ball cheaper than 24/40 standard taper? You can get a new 5pc 500ml distillation setup in 24/40 for $30 with free shipping.

I just wonder if you aren't taking into account things you might not think you need now but will want in the future, like a soxhlet extractor or a dean-stark trap, drying tubes, etc.

Also, apparatus with ball joints needs special clips and has to be supported in more locations than 24/40. I'd recommend going with 24/40 and getting a few 24/40 ST - 35/25 SJ adapters if you want additional flexibility.

Duster - 22-6-2016 at 05:14

Not cheaper, but only slightly more expensive. Granted I suppose it couldn't compare with a $30 24/40 setup no matter what... Most, albeit not all, of my glassware cost way more than that haha In my defense, this was back in the day before ebay had super cheap glassware.

I think I will do that though, get some adapters and proceed from there. I've never worked with ball joints before and I'd like to be able to just say I have.

Oh, as far as the source, I like eagle lab glass. Their prices are reasonable (for in house made in the USA), their customer service is excellent, and I also asked them to custom make a 1000mm graham condenser (this falls into the same category as the ball joints for me "because I can").

For example, their 1000ml RBF short neck with a 24/40 joint is $32.05, the same in 35/25 is $35.25. Part numbers are EG 8331 and EG 8351 respectivly.

[Edited on 22-6-2016 by Duster]

chemrox - 22-6-2016 at 07:08

24/40 in the us.. 24/25 in EU are the cheapest most common joints. 19 are common too. I use 14/25 with small scale experiments. BTW Chemglass seems to buy from many sources not all of them good. You can tell high quality borosilicate by it's being easier to clean. Used Pyrex (brand) is better than new Chemglass.

[Edited on 22-6-2016 by chemrox]