I’ve been using the Brownells Classic as I think it’s supposed to be a reverse formulation of the pilkingtons at about 1/3 the cost. I use a cotton swab that’s been barely dipped and wrung out so that all I get is a quickly dissipating dampness on slightly warmed parts. As in, only warm enough to be sure it’s dry and free of any water (it as dried after it came out of the boil, too) and acetone from the quick rinse given before each application. I will also use one of those little acid brushes like for applying solder flux, dipped minimally, to apply in serrations, dovetail cuts, and other impossible
to reach crevices that will show (not the frame insides). I do these spots first and then blot dry with a clean cotton-ball before proceeding with the open areas. Anything that looks wet get blotted dry right away to avoid any puddling or drips.
I’ve not used a box or tried humidification at all. Only hang in the garage during the day or overnight for about 10-12 hrs max. I presume less is better than more, honestly, and it’ll get there with enough applications. But I do get impatient when it looks pretty decent after about 6 cycles.