A C&P pistol stored in an attic is a pretty dry place.
Not in Corpus Christi, Texas, it ain't...
Still, I ran a test of cylinders, loaded one and sealed with candle wax. Loaded one and sealed with clear nail polish. Both ends were sealed, ball side and cap side. After storing four months in the garage in the fall (quite humid), the candle wax had a couple of hang fires. The one sealed with nail polish fired like fresh. I'm goin' with the nail polish, myself.
One thing, though, on a Colt, I found the candle wax had an advantage, the caps didn't fall out of the nipple, no cap jams. So, with the colt, I'll do both nail polish first, then wax the nipples.
This was a test to see if a cylinder could be left loaded for some time in humidity and still fire if sealed with something. I didn't apply fresh caps, fired as was after 4 months sitting in a humid environment. These things will fire reliably if properly loaded even if loaded over a period of time.