# Silicone grease and o-rings!



## kicken_bright (Feb 20, 2009)

I am sorry I had to start a new thread, especially one over a topic that is so largely discussed in so many other threads! I assume that is why my previous thread was closed.

(https://www.candlepowerforums.com/threads/223544)

But some information really needs to be shared and confirmed!
At the end of my previous thread, I was directed to another thread (this one: https://www.candlepowerforums.com/threads/207116) he suggested using pure silicone grease. However; it is very important not to use silicone grease on silicone o-rings! Several sources confirm this. Look at this website for instance: http://www.efunda.com/designstandards/oring/oring_chemical.cfm?SC=none&SM=Buna-N (Nitrile)#chem

After doing a little bit of reading, I have come to this conclusion.
For silicone o-rings, you should not use petroleum or silicone products.
For Buna-N (aka Nitrile), you can use both petroleum and silicone products!

Please someone correct me if I have made a mistake! I sincerely dont want people to be misinformed. Contrary to what many people have said, silicone grease is not ok for all o-rings, and petroleum is not bad for all o-rings. Can we finally have clarification on this? Once again, I apologize for starting another thread on such a widely covered topic.


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## Patriot (Feb 20, 2009)

Your points are perfectly valid but the moderator closed your previous thread because he'd like you to use/revive one of the existing threads on this topic. He just provided an example link for you, probably after performing a search himself, and just happened to pick a thread that was also closed.

If you use the search function (upper right) and type in:

"o-ring lube"

or 

"o-ring and thread lubrication"

or any other similar verbiage, you'll find many threads discussing this topic.

Good luck.


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## kicken_bright (Feb 20, 2009)

For clarification, its not _always _personal preference. I understand a lot of the times it _is_ personal preference, but there are scientific reasons that should be considered. I do feel bad, I feel like I am beating a dead horse.  but I am simply noticing that there is some bad advice floating around here, and also some good advice without scientific/factual back up.


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## kicken_bright (Feb 20, 2009)

To reply to Patriots comment: the moderator pointed me to another closed link. I don't think he intended me to write in that thread. I think my thread was closed simply for the redundancy. Which i totally understand. I simply want people to have some concrete clarification. And I am quite familiar with the search function.


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## Patriot (Feb 20, 2009)

Did you read my post?


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## kicken_bright (Feb 20, 2009)

yes i read it Patriot! lol:twothumbs I think we were typing at the same time


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## Patriot (Feb 20, 2009)

I believe it was just an accident that he referred you to a closed thread. He probably performed a search and picked the first thing he saw. It just goes to show you how many of these are closed by the moderators. In any case, admin prefers that we use one of the many existing threads for discussing this topic.

EDIT: Ah, yes...we were probably typing at the same time.


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## Zatoichi (Feb 20, 2009)

One reason petroleum lubricants aren't a good idea is that even if they don't damage the o-rings directly, it gets runny when heated (as someone already mentioned) and is displaced by water much easier than silicone grease. That means within a short time it may no longer be protecting the o-rings, and won't be helping with water resistance.


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## kicken_bright (Feb 20, 2009)

Thanks Zatoichi! I completely understand that petroleum jelly shouldn't be used for the reason u mentioned! Its just that some people claim petroleum will actually damage the o-rings, which may not be true in all cases. (but is still true sometimes) Seriously though, thank you for speaking truth!


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## RocketTomato (Feb 20, 2009)

Here is a post I wrote in a previous thread:

I agree, you should not use Silicone grease on Silicone o-rings.


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## kicken_bright (Feb 20, 2009)

Thanks for that link RocketTomato! I knew there were some good posts out there! The problem with the search function is that it does not decipher the good information from the bad information. Most of the posts include things like " I use X product and it works great!" I started this thread hoping that many cpf folks will find this information before they read some other misinformed comments! I gave it a simple title hoping it will come up first while searching!


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## dano (Feb 20, 2009)

Silicone based lube will make a silicone based O-ring swell, slightly, but this won't effect a flashlight that uses silicone o-rings to ant noticeable degree.


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## Zatoichi (Feb 20, 2009)

dano said:


> Silicone based lube will make a silicone based O-ring swell, slightly, but this won't effect a flashlight that uses silicone o-rings to ant noticeable degree.



This will probably the case, usually. If it's a big, thick o-ring though and already quite a tight fit on, say, a twisty tailcap or head that requires twisting to change modes, it might swell enough to get chewed up and need replacing quite often. If I rememeber correctly about the guy with the Eagletac, it appeared as if this is what happened with him. I'm not trying to be picky here, but it seems a possibility if only a small one.

There's always the option to buy your own o-rings of course, so you know what they're made from.


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## KiwiMark (Feb 21, 2009)

I have silicone O-Rings on my Jetbeams (you can tell by their colour) and would prefer to avoid using silicone grease on them. I will probably buy some Krytox before I have a need to lube my Jetbeams.


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## DM51 (Feb 21, 2009)

KiwiMark said:


> I have silicone O-Rings on my Jetbeams (you can tell by their colour)...


You can't tell the material of an O-ring from its color. O-rings of different materials are made in many different colors. It is unlikely that you have silicone O-rings, as silicone rubber compounds are unsuitable for use in dynamic applications such as this.
 
--------------------------------
 
I'll be replying shortly to other points raised by this thread.


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## DM51 (Feb 21, 2009)

*Re: Silicone grease and o-rings*




kicken_bright said:


> I am sorry I had to start a new thread…


 You didn’t _have to_ start it. The previous one wasn’t closed so that you could just decide to re-start it. You have violated two CPF rules in doing that. Go and read the Rules and work out which ones you have broken. 




kicken_bright said:


> … especially one over a topic that is so largely discussed in so many other threads!


That is one of the principal reasons why the previous thread was closed.




kicken_bright said:


> I assume that is why my previous thread was closed.


 I think you’re getting there…




kicken_bright said:


> But some information really needs to be shared and confirmed!


It already has been, many times. You just haven’t looked for it properly.




kicken_bright said:


> I feel like I am beating a dead horse


 … and indeed you are.




kicken_bright said:


> The problem with the search function is that it does not decipher the good information from the bad information.


Of course it doesn’t. It finds information, but a reader then has to make an informed assessment of its validity, if necessary by corroborating it with information from other sources.




kicken_bright said:


> Most of the posts include things like "I use X product and it works great!"


The stupid things that were recommended were the main reason most of those threads ended up being closed.




kicken_bright said:


> … it is very important not to use silicone grease on silicone o-rings!


 That is _misinformation_. 




kicken_bright said:


> I sincerely dont want people to be misinformed.


… but your posts have nevertheless managed to misinform.




kicken_bright said:


> I started this thread hoping that many cpf folks will find this information before they read some other misinformed comments!


Well, _you _didn’t find it, so what makes you think people reading your posts will be any the wiser? You have achieved the opposite to what you hoped.




kicken_bright said:


> silicone grease is not ok for all o-rings, and petroleum is not bad for all o-rings. Can we finally have clarification on this?


1. Silicone grease used on silicone O-rings can cause minor swelling, but not actual failure.
2. Petroleum-based products cause failure in _some_ O-rings (including silicone ones).
3. Silicone O-rings are designed for use as static seals. They are not suitable for the moving interfaces of flashlights. They have low tensile properties, with very poor resistance to abrasion and wear. They are unsuitable for dynamic applications, especially where a lubricant might be required. 
4. It is _safe_ to use silicone grease on all flashlights.
5. It is _not safe_ to use petroleum products on all flashlights.
6. The lives of some users can depend on their flashlights not failing at a critical moment – including members of the armed forces, firefighters, security and other emergency services personnel, scuba divers, and others.
7. It is therefore _irresponsible_ to recommend any petroleum derivative as a general lubricant for flashlights_._




kicken_bright said:


> Once again, I apologize for starting another thread on such a widely covered topic.


Please don’t make a habit of it. Thread closed.


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