The best method I’ve found for using POR-15:
Use a throw-away brush, gloves, long sleeves, and put on one heavy coat.
Concentrate on teh rusty areas, maybe even go over bad areas twice.
Wait about 6 hours, the POR-15 will still be a little tacky, and then coat it nicely with some Rustoleum black semi-gloss.
The paint will bond with the POR as it finishes drying…makes a hard durable coating…almost like poor man’s powder coating.
Ok I added a poll to this thing. Obviously its intended for rusty surfaces, but people use it to undercoat cars all the time, and who wants to spend the time and money getting their car re-oiled every year?
Whatever the technique, I would never just set and forget it. Regular washings and re-coatings should be the norm.