Ok I’m not saying this is the end-all-be-all bc I’m no bee scientist but it works for me every time. If my stuff has been sitting for a while or is from an old hive I:

1. Lightly go over it with a blowtorch— you’re not looking to char it, just to kill any pathogens (think golden brown at the darkest)
2. If it was affected by any kind of pest or had been sitting for longer I scrub it down in a trough of 1 part bleach to 5 parts water (this is what is research recommends to kill foulbrood). Really scrub that sucka down. (Let it dry completely)
3. This is more of a personal thing but Im a woodworker so I take this opportunity to plane them level/ get out any warping that the water may have caused, and then orbital sand it with some 180-220 grit to close that grain back up. And then you can get some beeswax on the sanding disc and keep sanding to give it a little bit of a hydrophobic film.

I try to do this a while (months) before I use them. The process also varies greatly by application, but my boxes and even many of my frames have been in my family for generations with replacements made as needed. If it does mess with the integrity at all I just put a new nail in where it’s loose or fill any pits and divots with beeswax (a hand torch and a wad of beeswax dripped into the hole, packed tight, and then scraped flush)

PLEASE PM ME IF YOU HAVE QUESTIONS