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Molybdenum disulfide grease - why I wont use it.
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PostPosted: Wed Dec 11, 2013 10:09 pm    Post subject: Molybdenum disulfide grease - why I wont use it. Reply with quote
I know many people use Molybdenum disulfide grease for lubricating helicoids, and indeed some manufacturers used it in the past as well, but I believe that many, if not all, no longer use it.
The reason is almost certainly the way the oil base separates out from the grease. This is something I saw over many years as a 'hands on' maintenance engineer. The drums of moly' grease in the workshop would always have a pool of oil on the surface, so before we scooped any moly' grease out we would stir it, something we didn't have to do with ordinary greases of any grade. In use the moly' grease didn't seem to separate if the grease was used in an application where it was more or less constantly being moved. One of the most common uses for moly' grease is the constant velocity joints on car drive shafts - something that sees high loads, speeds and lots of movement, and crucially a CV joint is encased in a rubber boot that contains it and serves to keep the dirt out and if the car is stationary for a long time the separating oil is contained where it will mix back in when motion occurs.



Ten days ago I was in my workshop and using some moly' grease, and as usual there was a pool of oil on the top so I stirred it and used it. Then I thought about its use in lenses and the separation issue, so I put about a tablespoon of grease in a plastic lid and left it on the bench, and the result is plain to see. That isn't hot grease melting, my workshop is stone cold. That's just moly' grease standing for ten days in the cold.


PostPosted: Wed Dec 11, 2013 11:42 pm    Post subject: Reply with quote
Many thanks for warning!


PostPosted: Thu Dec 12, 2013 1:08 am    Post subject: Reply with quote
How do I say "thank you" in russian?

Very Happy

Renato


PostPosted: Thu Dec 12, 2013 8:14 am    Post subject: Reply with quote
RSalles wrote:
How do I say "thank you" in russian?

Very Happy

Renato


спасибо (spasibo)


PostPosted: Thu Dec 12, 2013 10:55 am    Post subject: Reply with quote
What I see on picture is strange for me - I use MoS grease a lot and I've never seen separation. Maybe it depends on producer of grease and what kind of oil was used as a base? Moreover, I've repacked tube of grease once to other container; forgot about it to find it 2 years later - no change in consistence and no separation occurred. I think that what is observed here is not general rule.


PostPosted: Thu Dec 12, 2013 5:11 pm    Post subject: Reply with quote
This is why normal automotive grease is best. I have had a tub for nearly 30 years and no separation, no hardening.


PostPosted: Thu Dec 12, 2013 5:47 pm    Post subject: Reply with quote
I spent about 35 years as a maintenance engineer and in that time we had many suppliers of oils and grease, always big manufacturers like Mobil, Shell or Gulf, and it's something we saw a lot. The grease in the picture is Mobil.
If the stuff is moving it's OK, the oil stays in suspension. It's when it sits it separates. Which is why some of the old Russian lenses that I've cleaned up were so oily inside, the moly' grease had sat there in an unused lens for a long time leaving a sticky goo in the helicoid and oil running on to the blades.

Moly grease is similar to Copper Slip grease, which also separates, that is used as a high temperature anti seize grease - both are based on a mineral / metallic element suspended in oil, where general purpose grease is oil thickened with a soap like compound that mixes freely.


PostPosted: Mon Jan 20, 2014 1:37 pm    Post subject: Re: Molybdenum disulfide grease - why I wont use it. Reply with quote
Lloydy wrote:
I know many people use Molybdenum disulfide grease for lubricating helicoids, and indeed some manufacturers used it in the past as well, but I believe that many, if not all, no longer use it.

Lloydy wrote:
If the stuff is moving it's OK, the oil stays in suspension. It's when it sits it separates. Which is why some of the old Russian lenses that I've cleaned up were so oily inside, the moly' grease had sat there in an unused lens for a long time leaving a sticky goo in the helicoid and oil running on to the blades.


This is a very interesting discussion!

Molybdenum disulfide grease is widely suggested as one of the best for lenses, but this test, although a bit "rough", make me reconsider the whole discussion.

Now I have a question, Lloydy. What grease did you use with your russian lenses?

Broadly speaking, many people suggest high vacuum greases (example) or damping grease (example: NYOGEL 767A, wider list; 2nd example). Others suggest lithium grease. Nyogel seems to be a good choice, but I would like to have your opinion on this topic.

Another thing. What do you use to clean up the dirty parts? Isopropyl alcohol, avgas...?

Thanks! Smile

Last edited by bluesfun on Tue Jan 21, 2014 11:45 am; edited 2 times in total


PostPosted: Mon Jan 20, 2014 3:29 pm    Post subject: Re: Molybdenum disulfide grease - why I wont use it. Reply with quote
bluesfun wrote:
Lloydy wrote:
I know many people use Molybdenum disulfide grease for lubricating helicoids, and indeed some manufacturers used it in the past as well, but I believe that many, if not all, no longer use it.

Lloydy wrote:
If the stuff is moving it's OK, the oil stays in suspension. It's when it sits it separates. Which is why some of the old Russian lenses that I've cleaned up were so oily inside, the moly' grease had sat there in an unused lens for a long time leaving a sticky goo in the helicoid and oil running on to the blades.


This is a very interesting discussion!

Molybdenum disulfide grease is widely suggested as one of the best for lenses, but this test, although a bit "rough", make me reconsider the whole discussion.

Now I have a question, Lloydy. What grease did you use with your russian lenses?

Broadly speaking, many people suggest high vacuum greases (example) or damping grease (example: NYOGEL 767A, wider list; 2nd example). Others suggest lithium grease. Nyogel seems to be a good choice, but I would like to have your opinion on this topic.

Another thing. What do you use to clean up the dirty parts? Isopropyl alcohol, avgas...?

Thanks!

[edit]
There are some problem with the links (?)...
1st link: High vacuum grease, ellsworth.com/dow-corning-high-vacuum-grease-150g-tube/
2nd link: Damping grease, productsearch.nyelubricants.com/pdf/TDS_English_NYOGEL%20767A.pdf
3rd link: Damping grease list, web.archive.org/web/20080703160453/http://www.nyelubricants.com/lubenotes/LN_Damping_Grease-03-1.pdf
4th link: Damping grease 2, lubekits.com/?load=grease


Welcome to the forum bluesfun. You can't post photos or links in your first post, an anti-spam measure. You'll be OK from now on.


PostPosted: Tue Jan 21, 2014 11:44 am    Post subject: Re: Molybdenum disulfide grease - why I wont use it. Reply with quote
DigiChromeEd wrote:
Welcome to the forum bluesfun.


Thank you Wink

Quote:
You can't post photos or links in your first post, an anti-spam measure. You'll be OK from now on.


I should have guessed, indeed! I fixed the previous one! Thanks Smile

B


PostPosted: Tue Jan 21, 2014 4:30 pm    Post subject: Reply with quote
I use ordinary general purpose grease that any mechanic would use for car wheel bearings or that kind of application. There's no way a lens will subject a lubricant to anything like the pressures or temperature variations a good general purpose grease is designed to endure. I've never had any leaching of oil from it and it 'feels right' on focusing.

Something like this -
http://www.skf.com/uk/products/lubrication-solutions/lubricants/general-purpose-industrial-and-automotive-NLGI-3-grease/index.html

For cleaning I use tins of lighter fuel that I get from the Poundshop, it's way cheaper than Zippo lighter fuel and I can't see any difference at all.


PostPosted: Tue Jan 21, 2014 6:16 pm    Post subject: Reply with quote
Lloydy wrote:
Something like this -
http://www.skf.com/uk/products/lubrication-solutions/lubricants/general-purpose-industrial-and-automotive-NLGI-3-grease/index.html

May I humbly ask why you recommend an NLGI 3 grease instead of an NLGI 2 -- or even an NLGI 1 grease?


PostPosted: Tue Jan 21, 2014 9:00 pm    Post subject: Reply with quote
twinquartz wrote:
Lloydy wrote:
Something like this -
http://www.skf.com/uk/products/lubrication-solutions/lubricants/general-purpose-industrial-and-automotive-NLGI-3-grease/index.html

May I humbly ask why you recommend an NLGI 3 grease instead of an NLGI 2 -- or even an NLGI 1 grease?


The simple answer is, it's what I've got drum of in my workshop. Wink And that's it really, I've been an apprentice trained, hands on maintenance engineer for over 30 years and loved mechanical things since I was a kid, so I appreciate that certain applications require certain greases or oils for lubrication. I'm also retired so I have forgotten and lost touch with the technicalities, but one thing I did learn was to use what is necessary, which is not always the most high performing or technically advanced product available. There was a huge discussion on another photography forum a while back about grease for lenses after some guy recommended some grease that cost stupid money for a tiny tube, this stuff was used by NASA "so it must be good". It was good for shafts rotating at 1,000s of RPM in zero gravity and temperatures hot enough to fry eggs, but that's not what we want to do, so why not use something that just does the job perfectly adequately?
That link to the NLG1 3 could have been to any 'general purpose' grease really. I know the 3 has been OK in the British climate, but perhaps it's too thick for Siberia?

I know a lot of people disagree with what I say, and I'm certainly not saying I'm 100% right, there might well be better alternatives to 'general purpose grease', but Moly' grease is not one of them, and general purpose grease does the job economically, in my experience.


PostPosted: Sat Feb 15, 2014 8:52 pm    Post subject: Reply with quote
Here's the lubricant which is being used on LZOS and other soviet & russian ex and current optical plants for helicoids: http://www.microsofttranslator.com/BV.aspx?ref=IE8Activity&a=http%3A%2F%2Fwww.expert-oil.com%2Fsite.xp%2F050054056124049049054056.html

I've got a can of it, looks, smells and feels like plain white lithium grease.


PostPosted: Sat Feb 15, 2014 9:24 pm    Post subject: Reply with quote
CuriousOne wrote:
Here's the lubricant which is being used on LZOS and other soviet & russian ex and current optical plants for helicoids .... I've got a can of it, looks, smells and feels like plain white lithium grease.


It's apparently composed of polydimethylsiloxane, mineral oil, ceresin wax and lithium stearate, so I guess it makes it a lithium grease.


PostPosted: Sat Feb 15, 2014 11:25 pm    Post subject: Reply with quote
Gardener wrote:
CuriousOne wrote:
Here's the lubricant which is being used on LZOS and other soviet & russian ex and current optical plants for helicoids .... I've got a can of it, looks, smells and feels like plain white lithium grease.


It's apparently composed of polydimethylsiloxane, mineral oil, ceresin wax and lithium stearate, so I guess it makes it a lithium grease.


And a 'general purpose' grease. I wouldn't have any problem using a grease like that.

I cleaned a Rollei Planar 50 / 1.8 a few days ago, the focus was so stiff it was unusable. The helicoid was 'lubricated' with what looked like a two part mixture, a sticky black goo with oil. Yep, it was moly' grease and the oil was separate to the grease base. Thankfully it hadn't migrated on to the blades or the glass, but it was perfectly plain to see the dark grey grease and a thinner, entirely separate. layer of oil that had settled in the base of the helicoid, the lens had obviously stood for a long time with the front up.

I found a good site with lots of tech' about grease and the selection of greases, and one of the articles states -

Quote:
Additives

Additives can play several roles in a lubricating grease. These primarily include enhancing the existing desirable properties, suppressing the existing undesirable properties and imparting new properties. The most common additives are oxidation and rust inhibitors, extreme pressure, anti-wear and friction-reducing agents.

In addition to these additives, boundary lubricants such as molybdenum disulfide (moly) or graphite may be suspended in grease to reduce friction and wear without adverse chemical reactions to the metal surfaces during heavy loading and slow speeds.


http://machinerylubrication.com/Read/29223/selecting-grease-consistency ( a lot of good information on this site )

It's an additive to reduce friction and wear, something that is admirable and what we want a lubricant to do. But we aren't dealing with high pressures, high temperatures, high speeds or any other extreme conditions. All we need on a lens is a lubricant to reduce friction at low requirements, and a lubricant that doesn't rely on agitation to keep it's constituents in suspension. Which is what I'm convinced happens to molybdenum disulphide grease when it is used in a low pressure, low temperature and low agitation situation.

I think many lens manufacturers got blinded by the science and thought that the highest specification greases were the best option, when the reality was that a basic grease was probably the better option.
I have no idea what the shite was in the Yashica I also cleaned last week, the red gunge in that was more like glue, it might have looked good, it might have sounded good on the spec' sheet. It wasn't, and I'd bet that the general purpose grease I've used in both of these lenses will be still performing correctly for a long time, longer than the original lube.


PostPosted: Sat Feb 15, 2014 11:28 pm    Post subject: Reply with quote
Dave this is a perfect subject for a TTP entry if Attila would think again about creating such a category.

TTP: Tried, Tested and Proven. No fancy stuff, just good workable results.


PostPosted: Sun Feb 16, 2014 11:12 pm    Post subject: Reply with quote
I like the idea Phil, I agree that it could be a an excellent source of easily accessible information. but I'll reply fully on your post in the The Photographer's Café

http://forum.mflenses.com/tried-and-tested-techniques-open-message-to-attila-t64363.html


PostPosted: Thu Feb 20, 2014 1:32 am    Post subject: Reply with quote
I've been using http://www.micro-tools.com/store/item_detail.aspx?ItemCode=HG-10 this grease for a while now and really like it, the action is very light and smooth with my Rokkor 58/1.2 and FD SSC 50/1.4 and a good number of others.
And the thicker stuff, http://www.micro-tools.com/store/P-HG-30/Grease-Helical-30-Medium-8ml.aspx I'll be buying some to try.


PostPosted: Tue Mar 04, 2014 10:50 pm    Post subject: Reply with quote
I've seen the same separation with Lithium greases. I have seen the flat black interior of an astronomical telescope turn a different, darker, color due to the oil leaving the grease, and most greases give off vapors that can condense on lens surfaces, irises, and shutters. The best grease I ever found for telescope use is a synthetic used on car disk brakes, it stays where it's put, doesn't creep, doesn't emit vapors (up to about 600°C anyway), and is an excellent lubricant. It is expensive though... but cheaper than having to pull the optical equipment all apart to clean...

Andrew
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