I don't want it in , just around the outside where the bb presses up against the frame , I think but not sure but when pedaling in the rain the nylon cups deform just enough to let moisture in between the bb shell and the nylon cup then you get the creak for a few days until it dries out , thinking silicon would stop this happening .
I was just pulling your leg a bit and was fishing for a computer chip retort of sorts.
You do mean silicone, don't you? More probably, silicone sealant that applies as toothpaste but dries as rubber.
Yes, that would keep water out of the joint, provided it doesn't enter via the seatpost.
However, water is not the culprit but relative movement (fretting) between the frame and BB. There is plenty of squirm between the two and they will fret, no matter what. A non-emulsifier grease helps in the short term to prevent noise (not fretting, it only lubricates the fretting) but fretting by nature moves grease away and never replenishes it, so soon the creaking will come back. A ball bearing constantly re-circulates grease pushed out of pressure faces because of its design. A BB doesn't have such features. It is a basket case of design. I have no answer to the problem and I suspect there is no answer.
