Author Topic: Vaseline vs Silicone Grease (Read 360 times)

psychexplorer · « **Reply #20 on:** April 13, 2011, 02:14:13 AM »

Quote from: Shake on April 13, 2011, 01:49:32 AM

Quote
If you want information that's already been posted elsewhere you need to do what it takes to find it There's no point in answering questions twice, perhaps you should rethink your demands

everything has been posted everywhere, refs and chem books cover everything, total synthesis covers almost every mdma question. hive archives cover everything. to everypost we should now reply with an erowid link then complain how erowid and chemistry books already coverd it. we are all cooks cooking out of science refs and procedures anyway, we just know how to tweak our recipies and we know how they work

it takes more effort to find a reference than it would have taken to just say something like boil down vaso = silicone grease. then anyone on this forum who wants the answer has to go join up to the other forum to get it.

all to often i type a question into google, i find the same question someone has asked on a forum, no one gave straight answers they all complain how its already been coverd and how he needs to do more research bla bla bla. one person posts maybe a helpfull link, but sure enough the link is usually dead or you have to sign up to another forum, go through hundreds of posts to get probly an inconcusive answer. end of rant.

All that is needed is a bit of common sense. If the answer is reference-like and can be definitively accessed with relative ease, then a repost isn't necessary. That's why we UTFSE.

This thread is good because it is a discussion about personal experiences, not a 1:1 lookup.

Google's results are polluted. Lucky for us, this is a specialty forum which isn't full of repetitive garbage - at least it won't be as long as repetitive garbage isn't introduced by poor posting.

What's wrong with joining another forum? Ever since The Hive died, people have been bouncing back and forth from forum to forum, many of which are either gone or no longer accepting new registrations. Better get in while you still can. With all of the cooks, kidiots, and fantasy chemists running around, the chemical underground isn't going to be getting any more accessible.

akcom · « **Reply #21 on:** April 13, 2011, 03:55:43 AM »

the link lugh gave is some good stuff.
Dow corning grease is great and its worth every penny.

Quote from: aniracetam on April 13, 2011, 12:11:40 AM

don't understand all the clowning on pet. jelly, old-schoolers melted rubber bands in it and applied it to glass joints.
I have no problem boiling heavy mineral oil at room temp in the rotovap using straight pet. jelly

teflon tape is legit too

It's not that pet ether doesn't work, it's that silicon grease is just so much better. I mean 130C to 70C. I used to think my vacuum was shit because it didn't get down to the 2000 micron level it was supposed to. Turns out I just wasn't using it right.
Only problem is this can make getting clean fractions harder but that's just a good reason to use your fractioning column.

aniracetam · « **Reply #22 on:** April 13, 2011, 04:19:19 AM »

well, whatever works for ya.

pet. jelly hasn't been a contam problem for me with anything. I know this because I characterize with ESI-MS.

paranoidandroid · « **Reply #23 on:** April 13, 2011, 05:22:18 AM »

http://www.permatex.com/products/Automotive/lubricants/specialty_lubricants/auto_Permatex_Dielectric_Tune-Up_Grease_1.htm

Works okay for me...

2bfrank · « **Reply #24 on:** April 13, 2011, 05:33:44 AM »

Quote from: jon on April 12, 2011, 01:56:42 PM

yeah it kind of does matter silicone handle heat better it is'nt as likely to contaminate the distillate.
vaseline is good for the homsexually inclined.
use vacum grease not ass grease

hahahahah, Sounds like you know your grease, from your ass. hahahahah

akcom · « **Reply #25 on:** April 13, 2011, 07:41:35 AM »

While we're on the topic of distillation improvement, anyone here not already using ground glass thermometer joints is cheating themselves. The thermometers are a bit expensive but they're worth their weight in gold.

lugh · « **Reply #26 on:** April 14, 2011, 01:23:20 AM »

The best way to seal a thermometer well is with stopper with an appropriate sized hole in it

One can drill a rubber stopper with an ordinary drill if the stopper is frozen

A drill press works best for this kind of work

akcom · « **Reply #27 on:** April 14, 2011, 01:51:20 AM »

Quote from: Shake on April 13, 2011, 09:53:26 PM

thermometer fitting in the stillhead is no good? mine came with an rubber o ring type seal and a plastic thing to tighten it, but the higher vac would suck it in when warm i had to get a rubber cap thing.. what is the ground glass fitting one decent for? monitoring al/hg temp i suppose

i recently baught a digital thermometer that goes up to 300 i plan to make a custom rubber fitting for that in the stillhead so i can use digital thermometer when distilling..

and yes on the topic of vac distillation, i have a hunch my flat bottom flasks can take vacuum aswell, they are pretty thick walled, is that a myth about not putting fbfs under vac?

I've had no problem using a 500mL flat bottom under vac, it's thick walled though. The ground glass thermometer just makes a perfect seal. You don't need it per say, but if you want to distill safrole at 75C it helps

lugh · « **Reply #28 on:** April 14, 2011, 02:09:32 AM »

Another good way to fabricate a stopper is to wind the thermometer with ptfe tape in the proper position

letters · « **Reply #29 on:** April 22, 2011, 12:02:09 PM »

silicone grease is indispensable in vacuum distillations. Vaseline has a too low m.p. and is a bit reactive. And if you really think about it, silicone grease isnt all that expensive. Sure it costs more then a few bucks, but it lasts a life time. the vacuum grease tube i own is only half way through and ive bought it i think 5-6years ago. you use a small amount on each joint, so in the long run it comes out to be quite cheap!
some1 mentioned teflon tape - that is a bad idea, unless you know what you are doing. under high vacuum it is pressing down on the joints. if you use too much it will make stresses in the glass which will eventually lead to breakage. for normal vac distillation (rotovap vacuum) i dont mind using tape. but for high vac distillation, i wouldnt.
Cleaning silicone grease is easy - wet a paper towel with acetone and use it to clean your joints. it takes care of the silicone grease and its byproducts.

also, some1 said that they believe their thick walled RBF takes vacuum well. Any kind of RBF will take high vacuum. Ive distilled amines in a thin walled 100ml flask, 40micron vacuum. The only thing which is really important is that the glass is stress free. Stresses in the glass will lead to shattering. an extreme example of stress is the star type crack in flasks. you should inspect your flasks always before applying vacuum.
if you want to get all fancy and do it like the glassblowers do it, you should get a polarizing lens. shine light through it onto your glass and wear sun shades. you will see all stressed areas as colored areas going from pink to blue.

about the jointed thermometer - it is indeed very important. they do cost a bit, but they are great. Ive recently moved to gl-14 type joints, with a schott screw cap and a silicone sealing ring. you insert your thermometer through it and screw it onto your distillation head. works really well, and lets you adjust the height.

Shake · « **Reply #30 on:** April 22, 2011, 12:46:11 PM »

thanks letters, my pump is a killer pump but my ketone distills over too high, im gonna get the good grease for sure.

ALSO we said FBF not rbf lol i know we can vac down rbfs but im gonna use my fbfs for vac now because i dont believe the myth that they cant take it, maybe crappy ones cant take it

i thought all thermometer fitting had a height adjustment screw OR a rubber cap?

i cant really picture what you or ackom are describing but i think i already have one

letters · « **Reply #31 on:** April 23, 2011, 11:45:57 AM »

didnt notice the fbf thing, sorry. i can only offer what i know, which is - i imploded a 5L fbf while vacuum filtering a large amount of natural material. this was however due to glass stresses and not shape of flask. however, for high vacuum (i.e. <=1mmHg) you should however use rbfs.

akcom · « **Reply #32 on:** April 24, 2011, 10:53:00 PM »

Shake, we're talking about a 24/4 to 10/30 adapter along with a ground glass thermometer with a 10/30 joint. I'm sure you could find one on ebay

Methyl Man · « **Reply #33 on:** April 25, 2011, 07:09:21 AM »

Quote from: Enkidu on April 12, 2011, 11:16:48 AM

A friend used to wrap the male joints in teflon tape, like plumbers use.

I'll go you one better. Without wrapping the actual g/g male parts of the joints, after the apparatus is all set up, wrap teflon tape (but I mean the thicker, yellow gas line stuff) around the whole seam where the male part of the g/g joint meets the female. Stretching it a bit as it's wrapped around, so that the seam, or junction between the two pieces is sealed off. I hope that makes sense, it's kind of hard to describe. Anyway it really seals off the setup 100%.

blackr · « **Reply #34 on:** January 23, 2012, 02:21:57 AM »

I HATE messing around with grease and because of this decided to purchase some teflon sleeves. Their are two types, the cheap kind are simply thin teflon sleeves that work just as well the expensive ribbed kinds with "handles". They work great, perfect seal like grease without all the mess. I picked up some more not too long ago dirt cheap on Amazon, they probably still have some left. Lately Amazon has started stocking a lot of nice lab supplies and glassware.

nigluhS · « **Reply #35 on:** January 23, 2012, 12:34:54 PM »

shit...didn't dr gonz or Methyl Man warn us all of this WAY back?

use the grease, no doubt

reDEEMed · « **Reply #36 on:** January 30, 2012, 03:58:40 PM »

Quote from: akcom on April 12, 2011, 03:18:59 AM

For the longest time I was using vaseline instead of silicone grease, I just made the change today and I almost shit my pants. Usually safrole distills around 130C with my pump, my distillate today using silicone grease came over at 75C. I thought the oil was bunk, but the melting point was 11C on the dot. I'm sure its possible to get good vacuum with vaseline, but I think its probably immensely easier with silicone grease due to how viscous this stuff is. Anyway, just figured I'd let you guys know incase anyone else out there is using white petrolium instead of a silicone based sealer

OP, another advantage to using legit vacuum grease is that funky fart smell won't be in your distillate lol.

seeker · « **Reply #37 on:** October 15, 2012, 01:47:30 AM »

Dr. Glindemann seems to think Glindemann rings work best.

I suspect the reason the teflon sleeves performed so poorly was that the sleeves that arrive folded flat (most of them) were used. They probably work better after clamping and heating and molding to the joint.

A couple posters at SM have cut the sleeves into thin sleeves or rings with good results.

ordenblitz:
What I do is cut them into 4 or 5 smaller rings that actually seal better with less installation force. The narrower contact area allows for slightly more flexibility in joints as well. The only place I would worry is in very high vacuum applications where they could stress the contact point to a narrow area in the joint, or so I envision.

Neutrino:
Keep in mind also that sleeves can be cut up into multiple sealing rings. This way you can seal multiple joints for the price of one!

Author Topic: Vaseline vs Silicone Grease (Read 360 times)

psychexplorer

Re: Vaseline vs Silicone Grease

akcom

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aniracetam

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paranoidandroid

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2bfrank

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akcom

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lugh

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akcom

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lugh

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letters

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Shake

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letters

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akcom

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Methyl Man

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blackr

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nigluhS

Re: Vaseline vs Silicone Grease

reDEEMed

Re: Vaseline vs Silicone Grease

seeker

Re: Vaseline vs Silicone Grease