In 80s I used to use walnut hulls boil then wax on my canine traps. Then for a few years I tried dips you mix with white gas or good quality gasoline, and for several seasons I used rustoleum to paint them, and have tried and used FMJ type coverings for several seasons, too. I even had a friend powder coat some 1.5 coil coon traps for me one year, and that didn't hold up to my liking either for what I paid for the process. Was not a fan of FMJ or other floor wax coverings, and it was a PITA to remove it later when I wanted to switch back to something else.
In the most recent several seasons I've gone back to freebie dying with walnut hull boils and a straight hot parrafin wax covering afterward. New traps get degreased then waxed and used like that for one season (no boil), but then boiled the next and waxed. It just plain works.
I have no scientific proof of why or why not, but in 40+ years of trapping coyotes my catch rate was way off in years when I didn't use walnut hulls and wax. In addition, I had more severe trap rusting and freeze up issues in years when I didn't use a paraffin-type wax. I've also gone to using mostly waxed dirt for trap covering. Everything works to some degree, but wax has been best weather-proofing and reasonably cost effective method I've found so far.
For coon work, water or land, I don't care what you use on your traps coon will remove all of it after a catch or two. Straight wax actually works better for me on my coon traps, too.
All of those other trap preps I've tried worked to some degree, but were costly compared to freebie pick 'em yourself walnut hull boils. I get my unscented parrafin wax for a very reasonable price purchased in bulk and so far is the best weather-proofing, cost efficient, and trap protection I've found. Get the unscented 10 pound blocks of pure candle parrafin wax from hobby lobby and be sure to use their 40% off online coupon for the purchase. Have a friend also get a coupon and have them buy more for you, too. Its way cheaper than traditional "trap wax" and you can also shave the block in to fine curls with a block plane and use it to make waxed dirt, too.
I have a large "smart cooker" electronic crock pot cooker we got as a 2nd one year from family gifts. Only needed one for the kitchen and couldn't take the other one back. So I've been using it to wax traps in off-season. Take one of those 10 pound blocks of wax and bust it up into smaller pieces with a hammer and put those in the cooker. Set the temp to somewhere above the wax melting point and let it melt, add wax pieces until the cooker is mostly full but not overfilled so when you add traps the hot wax doesn't overflow. Mine holds 2-3 traps so takes me a while to do batches but I can do this on side while working on other stuff around the garage or yard, I can control the melting temp and with no open flame its super safe for waxing traps and other equipment like wire, hammer heads, trowel heads, etc. when I'm done waxing I unplug the cooker, let the wax in the cooker cool back to solid state then just put the sealed lid back on it and store the whole thing on a shelf in my garage. The sealed lid keeps other odors out of the wax until I need to use it again. Its super easy to re-wax traps after several catches, too. I bet a crockpot or two picked up at a garage sale would work well too.
Jim