I use it quite often. I like the way it make the coins look. though I don't know the exact level of protection it offers for Bronze disease
and the like, I would assume it gives at least a little, since it seals
out moisture and air.
I just apply it with my fingers, rubbing the coin vigerously with a generous dab. The heat from your hands
will warm the wax and melt it allowing it to get into all the pores and crevices. Then i let it dry and buff it out either by hand with a soft cloth , or with a soft nylon wheel on my Dremel mini mite. The Dremel gives a bity higher gloss so it is more a matter of preference than anything else.