Before assembling the hive, we suggest that you give a coat of NON-TOXIC paint/impregnating agent to all of the hive components. Let the pieces dry in the sun for a day or two. Water based paint normally has the least amount of toxins.
For installation. You can find installation instructions here: https://youtu.be/I638FTNdbZs
Once you’ve built the hive, give it a couple of coats of non-toxic or low VOC paint/impregnant to protect it from the elements. No matter what type of paint you use for your B-BOX, use any type you would use for a regular hive. It can be water-based, oil-based, etc. The most important thing is that it has low VOC levels or is non-toxic so as not to harm the bees.