Vaseline Vs Silicone grease

I just thought it would be a good idea to put something about these up here to clarify things, i've noticed occasional confusion in some threads. Most people know, but if you are just starting out then it's something you ought to learn.

Vaseline is the trade name of a petroleum jelly, it says so on the tub & there are a number of cheaper alternatives on the market. The words on the tub are a pretty good clue that it is a petroleum based product and before putting it anywhere your O ring you should read the label.

Vaseline used to be used for 'packing' in water resistant products which are mainly made out of metal, (and there are still some applications where this is a good method - not photography)you would fill all available space in the component with Vaseline so any water would find it difficult to penetrate. If water did/does penetrate the hope was that the Vaseline would protect the component from corrosion by leaving an oily coating on the metal.

Some divers coat their knives in vaseline to protect it against the salt water, i don't because i keep it well away from my diving kit as i don't want it on my O rings even accidentally.

Silicone grease is NOT a petroleum product, it's a thickened silicone oil used not to pack, but to lubricate rubbers and synthetic rubbers. It is not used to 'pack' as the products it is designed to lubricate are the correct packing in themselves.

O rings are made from rubber or plastic, they are so common today that we take them for granted, but they were a breakthrough in design in their early days. The rubber or synthetic rubber they are made from can be very, very alergic to petroleum products.

A cheap piece of rubber it might be, but your camera is at its mercy, treat it with respect. It is a piece of precision engineering designed to fit exactly into the space between the front & back of your housing and does not need any packing to make it fit, it does need a tiny, tiny amount of lubrication. look in any good jeweller's window at cultured pearls, a bead about that size is the maximum you should need on the end of your finger to lubricate your O ring. when applying the lubricant gently rub the O ring between your fingers (i'm assuming you have washed your hands before setting your camera us here), don't pull it along the length as this may stretch it and then it won't fit.

The debate as to which silicone grease to use is not one i propose to enter here, if you want to be safe use the one recommended/supplied by the manufacturer. and do NOT use it on the O ring in your cylinder especially if you are using nitrox, but that's a whole different topic.

WELL SAID.

If mfg. brand O-ring grease is not available, use saliva, preferably your own

There are a number of grease products that are not Silicone based and are fine for all types of O-rings. Look at the tribolube and christolube products. Saliva is a not very good idea. The reason that saliva keeps your mask from fogging is that it contains some proteins that make the glass hydrophilic enough to not condense fog. Bad idea for o-rings which are designed not to be coated with protein type stuff.

Bill

I don't agree. A dilute solution of proteins cannot be worse than an unnown mix of petroleum solvents.
I have had 2 very bad experiences with silicones.

When I was younger I had a pair of Hanson ski boots. These were the greatest thing for hard to fit feet. Custom fitted and the most comfortable ever. However, you needed a lubricant to put them on and the silicone spray destroyed the neoprene foam of the liners after about 8 years. Shells and everything else were still great, but no new liners to be had.

When I was an x-ray service engieneer I had the absolutely miserable task of rebuilding a machine that had silicone grease applied to large tubular teflon or delrin sleeve bearings (I can't remember which). The silicone grease swelled the plastic bearings and eventually siezed the pieces up. I had to disassemble and pull off 3000 lbs of equipment and spend a several hours hammering and chiseling the mess apart.

In the end, don't trust unknown hydrocarbon mixes around plastic and rubber compounds. The damage will occur and you will often not realize it until it is too late.

I didn't say that saliva was worse than vaseline, I just said that saliva was not a terribly good idea. The reason that you lubricate camera o-rings is to keep them soft and compressible. Not to make them slide, since in most camera designs the main o-rings (the ones you lubricate) are static. So I believe the best approach is to not use anything on them. The reason that I suggested some of the non-silicone lubricants was precisely what you say. Silicone oil can swell some rubber. Tribolube/Christolube and their chemical cousins will not swell any type of rubber that I am aware of and certainly not any of the common o-rings used in cameras.

Bill

I have never seen anyone use Vaseline on a camera O ring but I guess it happens, never heard of it. N

How about K-Y ?