That is an excellent idea and great tip. Like Bob Jameson, I use Vaseline, probably because Teflon tape was not invented when I started to "save" and salvage lure bottle caps.
Metal caps have a predilection for corrosion, but I like them over plastic caps, which can crack and break once in awhile. The trick is to not let the metal cap reach advanced rust/corrosiveness. Easy enough to say, especially when you are not paying attention when a partially used lure bottle gets parked in a refrigerator or on a shelf in the fur shed, or in the cellar until next season.
Oxidation is the culprit that destroys the integrity of the metal cap if preventative measures are not exercised. Over the years, I have concluded (only my theory) that the oxidation and corrosion on a metal cap from an "opened" lure bottle comes from air getting under the cap, combining with the vapors/solvents emanating from the lure ingredients and rising up to wreck the cap.
After washing and thoroughly drying the cap, I swab the inside with a gob of Vaseline, put the cap on the bottle and wipe off the excess Vaseline ooze. Then, I melt some wax in a tuna fish can, dunk the cap in it to "seal" it again. From there, the lure bottles are stored upside down until next season. My "upside down" theory is based on the fact that the ingredient's vapors and oxidants have no opportunity to attack the cap.
For lure bottles with plastic caps, I simply wash, clean, dry and seal the caps in wax.
Might be a bit of a lengthly response - no apologies because I wanted to express my experience with this topic in as much understandable detail as possible. An editorial review and comment for your consideration.
Regards,
Jonathan