Very interesting. Very well done.
Some years ago I read the account of a Civil War veteran who said he dripped wax (beeswax?) over the caps and around the ball after loading.
Later, I heard of beeswax softened by the heat of the hand, then moulded around the capped nipple.
In my own experiment years ago, loaded the carbon steel cylinder of my 1851 Navy and left it outdoors from about April through September.
I used Goex FFFG black powder, a thin wax wad cut from a milk carton on top of the powder, a greased felt wad, a .380 inch ball, and a CCI No. 11 cap. I formed a tiny beeswax "turd" and ran it around the cap, right where it meets the nipple. Then, I flattened the beeswax tight against the junction with the blade of a small screwdriver, as I recall. Or perhaps it was a stick; I can't recall.
Anyway, when fired months after loading every round appeared to emit the same, powerful sound. I didn't own a chronograph at the time and couldn't measure velocities.
I didn't dunk my cylinder in water, as you did, and that makes your report all the more interesting.
I keep some waxed paper wads in my shooting box, cut from milk cartons, to act as a barrier against moisture or grease from the wad contaminating the powder. A slightly oversized wad will give a good fit.
Years ago, in the early 70s, I soaked wads in straight paraffin or candlewax. It wasn't much for keeping fouling soft, but I'm sure it was a good barrier against moisture creeping in around the ball.
However, a proper, oversized ball should allow any moisture past it, unless the chamber is out of round. Perhaps the practice is moot.
As each year goes by, I am just amazed at the amount of tinkering that can be done with cap and ball revolvers. And most of that tinkering uses materials that were fully available to the old-timers: thick, waxed paper, felt wads, oversized balls, beeswax, etc.
Perhaps if we went back in time and talked to the old timers they'd look at us and reply, "We been doing that for years! Where you been?"