Sciencemadness Discussion Board

distilling without grease glass joints

foambastus - 7-4-2013 at 04:25

Hi everybody! I am brand new here and I have a couple of questions for you experts.

What can I use instead of grease (in glass joints) to distill alcohol from a spirit?


And changing topic: is it true that for distillation of nitric acid from kno3 and H2SO4 I can use H2SO4 as lubricant in glass joints?

Thank you for your help!

hissingnoise - 7-4-2013 at 04:36

Glindemann Rings?
PTFE, they'll stand up to anything . . .

confused - 7-4-2013 at 06:24

probably not reccomended, but is it possible to distill without the grease?

you can try silicon grease from the hardware store...from what i know it should not react with the alcohol, but you might want to check with some of the other members here

hyfalcon - 7-4-2013 at 06:28

When distilling nitric acid you can use H2SO4 for lube on the ground glass joints of your setup.

hissingnoise - 7-4-2013 at 07:06

Glindemann rings are so fucking easily misplaced that I tend to fall back on the old teflon tape . . .

chemrox - 7-4-2013 at 07:24

If you must have something in the joints use Teflon sleeves. Unless the joints are mismatched you shouldn't need a lubricant at ambient pressures.

vmelkon - 7-4-2013 at 08:23

Are you going to distill ethanol? I don't use anything. The ethanol wets the joint and forms a joint. There aren't large losses from the joints.

foambastus - 7-4-2013 at 08:54

Thank you everybody!

So, to summarize: to distill alcohol at ambient pressure I don't need lubricant and there are no risks of "frozen joints"

And I can use H2SO4 as lube for the HNO3 synthesis. Excellent..

Another question: for other experments is it possible to use the teflon tape (used by plumbers) instead of Glindemann ptfe? (I do not want to spend money for now...)

elementcollector1 - 7-4-2013 at 09:00

Use vaseline.

Hexavalent - 7-4-2013 at 09:22

I concur. I've always used vaseline/petroleum jelly when lubrication was necessary, and have never had any issues with contamination of the substance I was refluxing/distilling.

woelen - 7-4-2013 at 11:48

Quote: Originally posted by foambastus  
Thank you everybody!

And I can use H2SO4 as lube for the HNO3 synthesis. Excellent..

Another question: for other experments is it possible to use the teflon tape (used by plumbers) instead of Glindemann ptfe? (I do not want to spend money for now...)

You can use H2SO4 as lube for HNO3 distillation, but you can also leave out the lube. Some HNO3 will wet the joins and no further HNO3 escapes the system. You just need to use good clamps to keep the joins connecting well.

If you use vacuum distillation for the HNO3 then you may need some lube, otherwise air may flow through the joins and the joins may get stuck.

foambastus - 8-4-2013 at 06:19

Clear now, thanks.

The ethanol distillation was good without any lubricant.





Sciocrat - 8-4-2013 at 06:22

I usually use vaseline or no form of grease at all, and didn't have any problems so far.

MrHomeScientist - 8-4-2013 at 06:33

I use silicone grease from the hardware store, used to lubricate some part of a faucet fixture (I found it in the sink parts section, anyway). Also remember that if you do use grease, you only need to use it on the joints where vapor is present. I.e. after the condenser you shouldn't need any. I usually do anyway, since it only uses such a tiny amount.

Mailinmypocket - 8-4-2013 at 11:19

Look in the auto parts section of a hardware store or a NAPA or anywhere else where you can buy electronic car equipment (headlights, stereo wiring, etc) and find some silicone dielectric grease. It is extremely inert to everything I've thrown at it, I have had problems with petroleum grease like Vaseline with certain solvents...

It's cheap and will last you forever!

http://www.permatex.com/products/product-categories/speciali...