I need some grease for my vacuum desiccator. Does anyone sit on information if I can buy it OTC, or if I should "improvise" and use Petroleum Jelly
for instance...?
The reason why I ask instead of deducing some sort of cunning replacement is because I remember reading a thread here about someone who used a readily
available grease and had to throw away his desiccator because the lid wouldn't come off.
Any suggestions are appreciated!evil_lurker - 21-4-2008 at 13:52
I got it off.
Dow Corning high vacuum grease does indeed work, but, it will flat out set up. Stick it in the sun, and it will slide right off.chemrox - 21-4-2008 at 22:24
Use the Dow stuff-heat guns work miracles. Dow stuff is good for greasing fly lines too!ScienceGeek - 22-4-2008 at 03:43
Thanks a lot guys!
Also, is there some sort of grease that doesn't require a heat gun or sunshine to get the lid off again?tentacles - 22-4-2008 at 06:10
Perhaps silicone grease? It should be safe on almost anything. The stuff they use for dielectric grease on spark plugs is particularly thick. I've
had good success with it on my distillation rig doing nitric acid. (I use a thin layer under and over teflon tape)evil_lurker - 22-4-2008 at 18:59
5 degrees of difference is all it takes between easy on and easy off.ScienceGeek - 23-4-2008 at 08:45
Thank you very much for your replies! I'll see what I can find at my local hardware store! ScienceGeek - 26-4-2008 at 04:44
By the way...how about Glycerol? Could that be used, or might it be a problem?JohnWW - 26-4-2008 at 21:34
Why not try ordinary petroleum jelly, e.g. "Vaseline", which is a petroleum fraction intermediate in molecular weight between heavy diesel oil and
candle wax? When I was at university, we used "Apiezon" stopcock grease, for vacuum dessicator bells and for taps on vacuum lines,which was much more
expensive than "Vaseline", but seemed to have practically the same viscosity and other properties.ScienceGeek - 27-4-2008 at 06:16
I tried it! There was no doubt that there was a very tight seal, but it was hard to get the lid off after. But "hard to get it off" is still alot
better than "not getting it off" i guess! In my experience, Vaseline doesn't harden or anything, so I guess it will be fine bfesser - 28-12-2010 at 18:34
By the way...how about Glycerol? Could that be used, or might it be a problem?
Horrible, horrible idea--I'm sorry to say. It's hygroscopic on it's own. It'd be pulling water in from the atmosphere on the outside until it
becomes a watery mess, eventually pulling water into the desiccator. I have a small ground-glass dropper bottle I keep glycerin in for lubrication
and it's constantly pulling water into the joint--and making a mess!
[Edited on 12/29/10 by bfesser]peach - 31-1-2011 at 05:30
People usually complain about using Vaseline on glassware because it is not inert and can wash into the glassware from the tapers.
But with a vacuum desiccator, you don't have solvent rushing past to the results and you have a big physical gap between the seal and the sample.bfesser - 31-1-2011 at 16:03
My desiccator originally had what I think was silicone grease on it when I purchased it second hand. Everything slid smoothly. I wiped it off and
tried Vaseline instead with disappointing results. It tends to freeze or up more easily (not as good at lubricating). It also gets a lot of tiny air
bubbles in the joint no matter how carefully I slide the lid on. I just ordered a tube of the Dow Corning High Vacuum Grease to try out--hoping that
it'll be like it was when originally purchased.
I also decided to wash my desiccator while I wait for the new grease. It's sparkling clean now, which is very nice.
