How many of you have had so called waterproof flashlights leak? Yesterday I was talking with a friend who maintains electronic equipment for a living. He provided me with a simple solution. He seals his flashlights with Silicone grease once a year. I found some at ACE hardware, a small container cost me $4 and change.
You place a drop of the grease on the threads and tighten the seal. It does not damage the o-rings. In fact, on many of the waterproof flashlight the warranty is void if you don’t lubricate the o-rings with silicone grease. He says it will waterproof a Maglight quite nicely and keeps the threads from binding.
I have been sitting here waterproof flashlights, using a q-tip to spread the grease. It doesn’t take much grease just a drop. Try to keep from getting it on your hands it is hard to get off. It seems to work well. This can be used on o-rings used to waterproof electronic devices, just don’t get it on the electronic components.