Sciencemadness Discussion Board

Dow Corning Vacuum Grease Cleanup

rrkss - 19-6-2010 at 06:54

Anybody know a good solvent to remove Dow Corning High Vacuum Grease from glass after use?

bahamuth - 19-6-2010 at 06:59

I've had luck with KOH in Ethanol in the past instead of using expensive solvents.

Really not tried much else when I come to think about it...

rrkss - 19-6-2010 at 22:23

One of my collegues reccommended Dow Corning OS-2 as a simple solvent to remove silicone grease. Going to try that first before I resort to a more aggressive KOH Ethanol Bath. Thanks for the response.

rrkss - 20-6-2010 at 10:16

Was experimenting with various solvents I had on hand and surprisingly this stuff is perfectly soluble in Ethyl Acetate. Was able to clean my joints to a nice frosty color in a matter of seconds using Ethyl Acetate. Thought I'd share since this is a cheap and simple solvent.

smuv - 27-6-2010 at 18:27

chlorinated solvents, THF, acetone, ethyl acetate (in order of decreasing effectiveness). It also comes out in base bath but alcohols aren't the best solvents for it.

UnintentionalChaos - 27-6-2010 at 18:31

Remove as much as humanly possible with paper towels/cotton swabs/pipe cleaners, then swab out with hexanes or similar. At least, this was lab protocol when I was doing undergrad research. Acetone is the solvent of choice for apezion, IIRC.

[Edited on 6-28-10 by UnintentionalChaos]

peach - 3-8-2010 at 15:29

Funny I should find this topic by chance.

I just got my DuPont Krytox high vacuum grease through, which is a perfluorinated polyether thickened with their own magical Teflon.

Works like a superstar on the tapers.

Cleaning it back off is another thing. 98% sulphuric, white hot concentrated KOH, every solvent I have to hand... nothing. It needs mechanically wiping off for the most part, the bulk will never shift with chemical methods, as per the writing on the tin (which is actually a plastic tube, and it's not written on there...).

That's also a neat feature, as it's gradually filling the microscopic ridges in the taper grind, making them seal even better.

$100 a 2oz tube. Mmmmm....

Sorry, I'm gear whoring and boasting. :P

BromicAcid - 3-8-2010 at 17:15

UnintentionalChaos has it right on, wipe off as much grease as you can. Paper towels are cheap by comparison to solvents, wipe the joints until they feel dry almost. Then use any non-polar solvent, hexanes, pet ether, toluene, xylene, MTBE, and chlorinated solvents, these things work great. Acetone works pretty good too as well as EtOAc. MeOH doesn't work very well. Best of luck!

entropy51 - 3-8-2010 at 17:26

Quote: Originally posted by peach  
$100 a 2oz tube. Mmmmm....

Sorry, I'm gear whoring and boasting. :P
No need to explain. Perfectly obvious even to us common folk who realize that silicone grease works just as well and is cheaper.

peach - 4-8-2010 at 02:31

Quote: Originally posted by entropy51  
No need to explain. Perfectly obvious even to us common folk who realize that silicone grease works just as well and is cheaper.


Damn commoners everywhere, YUCK! :P

Silicon probably does work as well for most things, but I doubt DuPont would make Krytox if there wasn't a benefit to it; e.g. being sure there are essentially zero side reactions possible due to grease interaction. Needless to say, this upperchum didn't pay $100 for his tube.

I was having a read of Dow Cornings history on their site. Lots of interesting stuff in there. Personally, I prefer the helping premature babies stories over the luxury cars and military uses. I note they were the guys who started producing silicone insulated wire. If you've not used it before, you're missing out. The wires drape and flex like they're made of cooked pasta.

And I was reading the silicone wiki about the curing process producing acetic acid. I knew it was involved somewhere, given the delicious salt and vinegar crisps smell around freshly sealed bathrooms, but only just found out it's a product of the cure.

Now get off my lawn, proles!

entropy51 - 4-8-2010 at 06:43

Quote: Originally posted by peach  
Silicon probably does work as well for most things, but I doubt DuPont would make Krytox if there wasn't a benefit to it; e.g. being sure there are essentially zero side reactions possible due to grease interaction.
Krytox is used mostly in special applications such as uranium enrichment where the lubricants come into contact with UF6.

peach - 4-8-2010 at 06:53

Quote: Originally posted by entropy51  
Krytox is used mostly in special applications such as uranium enrichment where the lubricants come into contact with UF6.


Holy moley bat boy! I better reinforce the roof of the house before I get bunker buster bombed below brown, baron, burials beneath!

I bought it because I found some for the same price as regular vacuum grease, and DuPont say the high vacuum Krytox works great for laboratory glassware applications, which is does.

aonomus - 4-8-2010 at 12:08
Quote:

And I was reading the silicone wiki about the curing process producing acetic acid. I knew it was involved somewhere, given the delicious salt and vinegar crisps smell around freshly sealed bathrooms, but only just found out it's a product of the cure.


There are acetic acid curing silicones, there are methoxy curing silicones, and other types as well. The general acetic acid silicones from the hardware store are fine for most things, but they do a real number on any exposed copper, that is where the methoxy cure silicone comes in.

As for removing silicone grease, I have never really been able to get it to go into solution in a solvent. The best I have done is paper towel wetted with acetone, a quick wipe against a quickfit joint, and bang, its clean (enough). I suppose if you had conditions where even *slight* contaminants would ruin your reaction, you would have to try to solvate the grease. On the other hand, finger prints would do more harm at that point, and you would probably run the glassware through piranah solution (note: don't do this, its too dangerous!)

peach - 4-8-2010 at 15:59

Quote: Originally posted by aonomus  

(note: don't do this, its too dangerous!)


[gets his pen out]Anomus says... make... piranha... solution...[/bang]

I haven't upgraded to piranha cleaning yet. 98% sulphuric is current working great for sintered filter funnels, after a few washes, and sticking the spray gun on the hose into the drip tube to blow it through the frit. I've, retardedly I now see, used strong KOH to clean sintered frits before, than wondered why they fell apart. KOH is fine for solid borosilly glass. But the tiny bonds between the grains in a sinter rot away and it falls apart over time. It's acid or solvents as far as they're concerned.

Another stupid mistake I've made in the past is adding KOH crystals to the glass and then the water. Or dripping it through a funnel such that bits of crystal end up in the glass. It's not an issue, for me, in terms of it splashing back. But it does superheat the glass in one spot as it dissolves, which causes some of it to crack; albeit, the shitty no name glass I've had thus far.

But I have run into numerous problems where they'll require multiple 98% sulphuric, hot saturated KOH and solvents to shift them, alternating between all three and a small weapons grade supply of scrubby brushes on sticks to harass the culprit from within. So I piranha may be the dangerous route forward.

I've broken a fair bit of glass during cleaning, because I've had to wash and rinse it so many times. Provided I can safely handle the piranha, that may help deal with that.

I have heard first hand accounts of glass exploding when people have carelessly poured it over glass coated with organic solvents and such; e.g. their sintered filter funnel.

I get your drift about the finger prints, but I rarely poke my fingers inside the glass. Well, they won't even fit inside the smaller stuff, and I'm not a porker. But I have watched things like DCM rinsing the tapers clear of grease as it goes past.

It's not so much of a problem when you're reasonable sure something should work, or won't be harmed by it. But, when I'm experimenting with something I have no real support on, it's another thing to add to the long list of variables that need squashing down as low as possible.

entropy51 - 4-8-2010 at 17:05

Quote: Originally posted by peach  

I've broken a fair bit of glass during cleaning, because I've had to wash and rinse it so many times.
Handling and washing glassware without breaking it is a basic skill of the chemist. You might want to pick up that skill before trying piranha acid, which is never actually needed if you know how to clean glassware.

peach - 5-8-2010 at 04:06

Cleaning a beaker or simple flask is quite a lot easier than cleaning micro-distillation or sinter glass, you've got me beat there if that's your point. You don't know what kind of glass I'm cleaning, what kind of environment I have to do it in, how often I'm doing it, what's in the glass or any of the other variables.

Are you drunk tonight? Hence the replies? Hopefully.