Stuck oil paint tube caps

​HI,

this is probably one of the dumbest questions you have had, but here goes anyway: I don’t always remember to clean the threads on the tubes, and just screw the caps back on after squeezing paint out. I usually get away with it, or having the caps just being a bit tight. But sometimes I may not use that colour for some weeks, or months, and the cap is well and truly stuck. (for some reason it doesn’t affect all my tubes).

I saw a video on Youtube which showed someone upending the tube and placing the threaded part into just off boiling water. That  works, although sometimes has to be repeated once or twice more. I then squeeze out the paint that was in the threaded part of the tube and discard it.

I tried to scrape off just the hardened paint holding the cap to the threads, but caps wouldn’t budge. Tried using a rag and some multigrips but just broke part of the caps (tubes still salvageable).

Apart from getting my act together and (1) carefully cleaning the threads (and inside the cap) after using the tube, have you got any other better ideas? (2) Is my Youtube hot water method likely to damage the paint in the body of the tube nearest the threads? It seems to look and handle OK afterwards, but just worried that the hot water might damage the paint in the top part of the tube which might cause problems later down the track.

Appreciate your feedback