For years this bottle of DeoxIT has been covered with a very thin layer of red juice, despite having the lid screwed firmly in place and a cap (removed here) pushed over the tube:
Turns out that there’s a minute crack in the cap. Every time I use the bottle, I refresh the oil layer on the inside of the bottle, which then gets pumped outside through capillary action. I’d been keeping the bottle in a tall ziploc baggie, specifically to contain the oil, and always assumed it was a simple leak.
The bottle still contains a lifetime supply of DeoxIT that may become a cherished family heirloom, one to be handed down through the generations. I can’t think of a better applicator, either, so I’m kind of stuck with that cap.
The cap is, of course, un-bondable polyethylene covered with thin oil, so there’s no possible way to repair it. I wiped it down with alcohol and acetone, then quick-like-a-bunny dabbed on a blob of Duco cement (which is the irregular shape on the cap) and worked it into the crack, in the hope it would stick well enough to reduce the pumping.
We shall see…