Hello,

I was reading some old posts about waterproofing plywood. The advice
was to paint the edges with metal primer. Why should you use a metal
primer rather than a wood primer?

Which metal primer should I use? In my local shed there a metal
primer for ferrous metal, metal primer for rusty ferrous metal,
special primer for non-ferrous metal, and red oxide primer. What's the
last one for?

I also found an aluminium primer which counter-intuitively is not for
aluminium but for wood. Is it so called because it contains aluminium?
I read that it stops knots showing. I might buy this next time because
if it saves having to do a separate application of knotting solution,
hopefully this will speed things along.

Thanks.