Utility poles get preservative plugs inserted into them on a schedule — the same moisture-activated rods go into a hole drilled in a fence post, where they diffuse through damp wood and stop rot and insects from the inside.
The band that shows up where a wall was painted in two sittings is a wet-to-dry join. Roll into your still-wet cut-in, reload before the nap goes dry, move no more than one roller length per section, and lay off as you go — not later.
