Just picked up a Lyman cast Manual #3 (and what I believe is #2).
I always like to read through new manuals cover to cover, mostly for entertainment, but also to keep myself sharp, and you never know what you'll learn!
Anyway, the manual suggested using boric acid on the top of the lead to create a vapor/oxidation barrier.
I've heard of people using sawdust ontop of the pot before, and I honestly son use anything.
I was just wondering if this is a very old school method, and if anyone still practices it?