A permanent grease for sealed microscope components: Krytox

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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mneium
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Joined: Fri Mar 13, 2020 7:15 pm

A permanent grease for sealed microscope components: Krytox

#1 Post by mneium » Wed Apr 22, 2020 12:38 am

I've been reading up about microscope repair and one of the demons of the industry seems to be solidified grease. My mind came to a grease I'm familiar with from building keyboards (it is often used to grease switches in custom mechanical keyboards): Krytox. This stuff is not silicone grease, it's pure PTFE. The lubricant itself is PTFE, and to make the grease it's thickened with... more PTFE. Don't ask me how that works. Since PTFE doesn't go bad, there is apparently no service life for it: "Grease samples from 20-year-old bearings have been examined and the grease was found to be in good condition."

The cost is steep, a 2oz tube is $40. It is however really, really nice grease that essentially futureproofs the moving parts of your microscope. It's also one of those cases where a little goes a long way. Just the slightest application with a paintbrush has my BH-2 head's IPD adjusting like butter, and it feels nice to know it will probably remain that way even after I'm pushing up daisies.

I can recommend GPL 204, 205, 206 or 207 for microscopes. They go in ascending order of viscosity. The line goes all the way down to 201, which is rather thin. There are also oils that are compositionally similar to the grease but un-thickened: GPL 101-107.

I wouldn't use this stuff on exposed stage bearings because it's just too expensive to replace often, but for everything else that needs to slide nicely and do it for a long time, there is AFAIK nothing better.

MichaelG.
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Re: A permanent grease for sealed microscope components: Krytox

#2 Post by MichaelG. » Wed Apr 22, 2020 8:22 am

Very impressive performance !!
Thanks for the link to the note.

MichaelG.
Too many 'projects'

Rorschach
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Re: A permanent grease for sealed microscope components: Krytox

#3 Post by Rorschach » Wed Apr 22, 2020 8:17 pm

Thanks for this, highly interesting!

I have a few different Nye synthetic lubricant products for my scopes. They seem to be well regarded but I have no long term experience yet.

mneium
Posts: 38
Joined: Fri Mar 13, 2020 7:15 pm

Re: A permanent grease for sealed microscope components: Krytox

#4 Post by mneium » Wed Apr 22, 2020 9:09 pm

Rorschach wrote:
Wed Apr 22, 2020 8:17 pm
I have a few different Nye synthetic lubricant products for my scopes. They seem to be well regarded but I have no long term experience yet.
Nyogel - I have used it for many years. Another expensive lubricant. It is popular for flashlight threads.
It eventually seems to cloud up and become not as slippery, but I'm sure it would long outlast your average silicone stuff from a hardware store.

abednego1995
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Re: A permanent grease for sealed microscope components: Krytox

#5 Post by abednego1995 » Sun Apr 26, 2020 1:51 am

Excellent stuff! I just got a 2oz tube of 206, and
it works wonders. I've went as far as relubing most of my objectives with correction collars, no sticking again! (hopefully)

BR,
John

mneium
Posts: 38
Joined: Fri Mar 13, 2020 7:15 pm

Re: A permanent grease for sealed microscope components: Krytox

#6 Post by mneium » Wed Apr 29, 2020 12:39 pm

abednego1995 wrote:
Sun Apr 26, 2020 1:51 am
Excellent stuff! I just got a 2oz tube of 206, and
it works wonders. I've went as far as relubing most of my objectives with correction collars, no sticking again! (hopefully)

BR,
John
206 is great - IIRC it is the most popular choice in keyboards. The heavy greases are versatile. You can always dilute them with more oil (minor correction to the OP - it is apparently PFPE oil, not PTFE) to reach lower grades of viscosity, but you can't practically add more thickener to reach higher ones.

mnmyco
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Re: A permanent grease for sealed microscope components: Krytox

#7 Post by mnmyco » Fri May 01, 2020 5:35 am

Pure PTFE is a solid until ~327 C and is practically insoluble in everything. Anything claiming to be pure PTFE and is not a solid is not pure PFTE and has a carrier in it.

mneium
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Joined: Fri Mar 13, 2020 7:15 pm

Re: A permanent grease for sealed microscope components: Krytox

#8 Post by mneium » Fri May 15, 2020 11:11 am

mnmyco wrote:
Fri May 01, 2020 5:35 am
Pure PTFE is a solid until ~327 C and is practically insoluble in everything. Anything claiming to be pure PTFE and is not a solid is not pure PFTE and has a carrier in it.
Yeah, the oil is PFPE and it's thickened with PTFE, my bad.


In doing some research on PFPE oils today I found something interesting. Dupont makes two basic formulations of PFPE oil - one is GPL (general purpose lubricant) and the other is VPF (vacuum pump fluid). VPF is about 2x-3x cheaper than GPL. I initially thought it was a lower-grade product, but four-bearing tests reflect that it actually has slightly superior lubrication & bearing wear results compared to GPL. The chief difference seems to be temperature resistance. GPL sustains high temperatures (greater than 200C) better than VPF. Not a big deal for our purposes. VPF also is specifically formulated to avoid evaporation since that's a big problem in vacuum pumps. And that should mean if you apply it inside a microscope, it'll stay there longer.

To give a "TL;DR": if you're buying a flourinated oil for microscope maintenance, go with VPF instead of GPL because it's both cheaper and better. You could also purchase ultrafine PTFE powder and make your own grease with VPF oil. Should work out to a relatively cheap version of this rather expensive grease.

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