# What's so special about Silicone dielectric grease?



## MedSailor (Mar 30, 2008)

I was at west marine the other day and saw the itty tiny tube of silicone dielectric grease (anchor brand) which was about as expensive as you would expect a high-end tube of cosmetics to be.

Over in the trailer wheel bearing grease section was this:









Would this work for keeping electrical contacts rust free? Is all silicone grease the same or is there something magical about dielectric grease?

Now for the stupid quesion: What exactly does dielectric mean anyway? If it is just an insulator than smearing it all over your connections seems like a bad idea...

MedSailor


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## Maine Sail (Jan 6, 2003)

MedSailor said:


> I was at west marine the other day and saw the itty tiny tube of silicone dielectric grease (anchor brand) which was about as expensive as you would expect a high-end tube of cosmetics to be.
> 
> Over in the trailer wheel bearing grease section was this:
> 
> ...


Dielectric means it blocks conductivity and hinders it. I am not a huge fan of anything silicone as it is as near permanent as can be. I prefer No-Ox-Id A Special. You can buy it at Sailors Solutions...

Here's a good way to see how permanent silicone is. Take two ends of a battery cable and print labels from a Brother P-Touch or similar. Smear one end with silicone dielectric and leave the other end bare. Be sure to get some smear on the wire jacket as happens naturally.

Now wipe off the silicone end and clean with what ever bionic cleaner you can find, acetone, MEK, Naptha what ever you want. When you THINK you have it clean try to put two labels on and compare how they stick... I know the answer....


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## maccauley123 (Sep 2, 2004)

Wouldn't that permanence be a good thing when trying to keep electrical connections moisture free?


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## Ulladh (Jul 12, 2007)

I use Dielectric Tune-Up Grease from an auto parts store to protect exposed electric connections; rubber boots on Perko 2 pin deck connections for the outboard (for battery charging) , solar panel and very old tiller pilot. You can also use it as directed for protecting spark plug boots and cables.


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## pdqaltair (Nov 14, 2008)

maccauley123 said:


> Wouldn't that permanence be a good thing when trying to keep electrical connections moisture free?


Not really. The "permanent" effect MS spoke of is on the PVC insulation (or gelcoat or ABS) and not of the wire itself. It's a plastics absorption thing, not relevant to metals. On corrosion testing it does not better than other water proof grease.

I also hate the feel when I get silicone on my fingers; I feel like I can't grip anything for an hour, no matter how I wash.

But it does have some very good applications. Head lube and Marlon through-hull lube are two where you are trying to keep plastic slippery.


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## svHyLyte (Nov 13, 2008)

MedSailor said:


> I was at west marine the other day and saw the itty tiny tube of silicone dielectric grease (anchor brand) which was about as expensive as you would expect a high-end tube of cosmetics to be.
> 
> Now for the stupid quesion: What exactly does dielectric mean anyway? If it is just an insulator than smearing it all over your connections seems like a bad idea...
> 
> MedSailor


Dielectric means a material is a poor or non-conductor as you surmise. Silicone dielectric grease is typically used to protect exposed electrical connections which are prone to corrosion in a marine environment without protection. It is also an effective lubricant for seals, gaskets, O-rings and the like that might deteriorate by exposure to hydrocarbon based lubricants. Silicon grease can also remain effective at extreme temperatures--in some cases up to 400ºC--which makes it an effective waterproof lubricant for bearings in boat trailers.


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## olson34 (Oct 13, 2000)

Whatever keeps corrosion and the resulting lowered conductivity away is likely a Good Thing.
When I was young, folks used to smear some vaseline around the battery terminal contact points on cars.

I got a bit older and once had a car refuse to start until... we took off the (dry but corroded) neg. terminal clamp, cleaned up the post, and reclamped it.

Heart of the matter is that 12 volts just is not very much "potential" and is easily slowed or halted by loose conections or bits of corrosion. 
My father used to tell me about how much worse things were, car wise, when their early-days electrical systems were six volt.

LB


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## hellosailor (Apr 11, 2006)

There's all kinds of grease. Silicone grease is generally stable (doesn't oxidize, doesn't migrate) and SuperLube is simply one good brand that has teflon particles added to it for added lubricity. However, you will see some "liquid" running from SuperLube at times, it may migrate more than the "high dielectric" grades. 

IIRC the "Al-Ox-It" type corrosion inhibitors also have some zinc dust in them to help avoid aluminum corrosion, and for general use many of us prefer not to have any metal dust in the non-conductive grease. it may or may not actually matter, from what I've heard.

In dielectric grease, you can pay $2 for 1/8 ounce in the little squeeze-pack designed from ignition points or spark plugs, $4 for 1/2 ounce tube, or $5 for an EIGHT oz. tube sold as "high tmeperature silicone brake grease" which is used in larger quantities on wheel brake components. Yes, you grease brake parts. Really.

You can also buy it as "light bulb grease", very similar product usually designed to make sure it doesn't migrate at all (dripping down bulbs) $3-4 an ounce tube.

There are lots of options, lot of names, product varies a little bit but any of them should work. And as Maine points out, silicone can "contaminate" forever, but in the right place, that's not going to be a problem.

Vaseline will also work, but that does conduct (very slightly) and certainly does migrate as it heats up.

If you think the Ancor stuff (which is a very good grade) is expensive, just look at the brand name "ignition point grease".


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## MedSailor (Mar 30, 2008)

So it is non-conductive, sticky, and tenacious. Here's what I've never been able to figure out, if you smear it all over your battery post/cable connection, then next time you remove and re-clamp it, you'll have some of that insulating grease between the post and cable akin to a thin film of insulating plastic between the connections. Wouldn't that be a bad thing?

MedSailor


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## pdqaltair (Nov 14, 2008)

hellosailor said:


> "Al-Ox-It" type corrosion inhibitors also have some zinc dust in them to help avoid aluminum corrosion, and for general use many of us prefer not to have any metal dust in the non-conductive grease. it may or may not actually matter, from what I've heard.


I've run the tests.

No-Ox-Id (Sanichem) does not contain Zn dust and a petroleum with corrosion inhibitors. The most effective product available for a marine environment, based on 12 months in a salt cabinet.

No-Alox (Ideal) is silicon grease with Zn dust. It is really for Al wiring, but it does well with copper too.

There is no point in comparing these in the same statement; they are not related. Neither conducts electricity in any practical sense; there are conductive grease products made for switch gear, but not these. Neither is appropriate for electronics.


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## hellosailor (Apr 11, 2006)

pdq-
Thanks for the clarification! No-Ox sounds like the better way to go, but at this point I'm still a silicone grease fan. Doesn't just last a long time, lasts 'forever'.

Med-
"you'll have some of that insulating grease between the post and cable akin to a thin film of insulating plastic between the connections. Wouldn't that be a bad thing?" Yes, that would be a bad thing. Except, when you snug down the connection the grease is displaced and there is a metal-to-metal contact which carries the connection. You only have grease between the surfaces where the metals aren't really in contact, or if you haven't tightened them down.
If there's no concern about current leakage from one wire to the next, by all means use anitseize or some other metal-doped goop instead. Personally, I think either will work well at preventing corrosion, but I like the idea that the silicone grease simply can't create any trace current leaks, or shorts of any kind. From telephone jacks to battery cables, it has worked well for me. No complaints at all.


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## MedSailor (Mar 30, 2008)

hellosailor said:


> pdq-
> Thanks for the clarification! No-Ox sounds like the better way to go, but at this point I'm still a silicone grease fan. Doesn't just last a long time, lasts 'forever'.
> 
> Med-
> ...


That makes sense. I figured it was the right stuff to use, it just bugs me when it doesn't make sense to me. Thanks for the clarification.

BTW does anyone have a good source for cheap silicone dielectric grease or the NO-OX that was mentioned? I don't like paying what Ancor marine charges.

Maine do you sell the good stuff?

MedSailor


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## pdqaltair (Nov 14, 2008)

MedSailor said:


> That makes sense. I figured it was the right stuff to use, it just bugs me when it doesn't make sense to me. Thanks for the clarification.
> 
> BTW does anyone have a good source for cheap silicone dielectric grease or the NO-OX that was mentioned? I don't like paying what Ancor marine charges.
> 
> ...


MS gave a good source for the No-Oxid above. My only source was industrial and wouldn't help.

As for silicon grease, the Superlube is not a bad low cost choice. It is always $$$. And it is good stuff. It does pay to work neatly, though. Also note that if you get it on the wire the adhesive shrink doesn't work so well.


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## denverd0n (Jun 20, 2008)

MedSailor said:


> Would this work for keeping electrical contacts rust free?


Short answer to your question: yes. SuperLube actually works quite well as a dielectric grease.


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