re: Source for small black oxide wood screws?

I was going to suggest the same thing, but that would make the slot smaller. Brass black is about a thin of a coat you can get but is not durable. The Rustoleum spray can with clear enamel is extremely durable (not even sand paper can remove it), it takes very few coats (3 at the most), you can re-coat any time, it dries super fast (less than 5 minutes), and did I mention durable?