Sciencemadness Discussion Board - Mysterious orange-brown residue inside used glassware

Mysterious orange-brown residue inside used glassware

Duff - 22-6-2020 at 09:56

I bought a used Schlenk line off ebay. It looks great, but it has some residue left inside from the previous owner. See the attached picture. I messaged the seller on ebay to ask what it might be, and they said they buy their stock from closed labs and auctions, so they have no clue. What sort of solvent and precautions should I take to clean this?

DraconicAcid - 22-6-2020 at 09:59

It's probably old stopcock grease.

Sigmatropic - 22-6-2020 at 11:58

Don't inhale or ingest it, avoid skin contact, Clean it in a well ventilated area. Even if it is one of the nasties, it wouldn't harm you if you take, what I call, normal precautions.

Then again I'm with draconicacid and wouldn't expect any significant amount of nasties in a schlenk line.

[Edited on 22-6-2020 by Sigmatropic]

Tsjerk - 22-6-2020 at 12:07

I would start with soaking with acetone.

mackolol - 22-6-2020 at 12:14

Yeahh.. for sure dont eat it, dont sniff it neither inject it anywhere.
I'm pretty sure whatever it is washing it with sulfuric acid will work, if not try piranha.

SWIM - 22-6-2020 at 13:40

I've used 10% bleach soaking on a few mystery deposits I didn't want to, or couldn't, get close to.

A few days in a bucket of bleach will eat most things organic.
Or stop up all the apparatus' joints and just fill it (leave a vent hole or loose stopper on top.)

I do try solvents and acid of some sort first, but this is a last resort short of piranha, and fairly cheap to buy at pool supply stores.

But the odds of it being all that dangerous are low.
I'd probably just scrub that out in the garage sink with gloves and wash up after.

I've dealt with a lot of brown to black mystery deposits in used glassware over the years, and I still haven't developed any super powers.

UC235 - 22-6-2020 at 15:42

Quote: Originally posted by SWIM

I've used 10% bleach soaking on a few mystery deposits I didn't want to, or couldn't, get close to.

A few days in a bucket of bleach will eat most things organic.
Or stop up all the apparatus' joints and just fill it (leave a vent hole or loose stopper on top.)

I do try solvents and acid of some sort first, but this is a last resort short of piranha, and fairly cheap to buy at pool supply stores.

But the odds of it being all that dangerous are low.
I'd probably just scrub that out in the garage sink with gloves and wash up after.

I've dealt with a lot of brown to black mystery deposits in used glassware over the years, and I still haven't developed any super powers.

Absolutely do not soak high vacuum glassware in anything vaguely caustic. The stopcocks should be individually paired and to much tighter tolerances than most stopcocks and you do not want to etch them.

I believe hexanes were the preferred method of removing silicone grease back in school. Feel free to try acetone and ethyl acetate too.

DavidJR - 22-6-2020 at 16:01

DCM works well for removing old nasty grease.

SWIM - 22-6-2020 at 17:45

Quote: Originally posted by UC235

Quote: Originally posted by SWIM

Bleach etches glass?
Never heard that before.

Also, if a high vacuum valve needs a matched core, the are high vacuum valve bodies without their cores no longer suitable for high vacuum work?
How can a matched core be replaced?

I thought a high vacuum valve was merely a valve with a covered small end so the vacuum ensured strong valve seating.

Duff - 4-7-2020 at 12:39

Ok, so I set up the Schlenk line at a little bit of an angle, and then put a stopper at the lower end, on the side with the residue. Then I used a funnel with a tube to pour acetone down the line until the dirty tubes were filled up. I'm going to let it soak for a while, then I'll place a bucket below and pump in water to rinse it out. How long do you figure I should let it soak?

[Edited on 4-7-2020 by Duff]