This is one of the questions what confuses people the most. Many underwater camera shops display their greases wrongly also. Here's what I have gathered about O-rings and their greases:
- The coloured O-rings made for underwater camera equipment are made of silicone rubber. Do not use a grease that has silicone in it.
- Most of the O-rings.. plumbing, DIY etc.. in the world are made of Nitrile rubber and are usually black. These can be lubricated even with silicone grease. For a fact I know that all ikelite housing O-rings are Nitrile. (From plumber's merchant you can also buy dark brown O-rings that are actually made of silicone)
- How to recognize the two different materials? If both O-rings are not lubricated the silicone rings feel much more slippery between your fingers. The silicone O-rings also are softer if you squeeze them between your thumb and index finger.
- How to know if O-ring grease has silicone in it or not? This is the hard part as many reputable shops label their O-ring grease as "silicon grease" even when the grease does not contain silicon. Sometimes you hear a word fluorosilicone mentioned when talking about these kinds of greases. Most of the greases in UW-photography world are these types and can be used with all O-rings without fear of swelling. Interestingly Sea & Sea say that their grease includes silicone... when in practice it has been known to work with all O-rings. It could be that their silicone is the fluorosilicone type.
- If you have bought Ikelite products you need to be careful. Their stock grease includes silicone and should not be used with any other brand. Hence my advise for Ikelite users, who mix and match other types of lights for example... is to throw the grease away and use generic O-ring grease.
- Safe greases for all O-rings are at least: Sea & Sea, Inon, Olympus and Nauticam. I'd be wary of grease from a builder's merchant as many of these include silicone
- I'm sure there are all sort of weird exceptions to these rules
- I should add that even Sea&Sea used to do two types of grease. Years back I saw Sea & Sea grease in a white tube with black cap. This grease was somehow different. The current yellow tube the only type I have seen for years.
Edited by Juzzi, 08 August 2014 - 02:45 AM.