The chalk marks
Four marks exist in our bay. A single slash means companion stringer. A cross means deck board replacement. A circle means re-nail only. A line through the whole pallet means core — it goes to the de-nailer, and its useful boards become somebody else's repair.
Graders develop the sounding reflex within about a month: struck with the flat of a hand near each stringer, a solid pallet rings and a cracked one thuds. After that they cannot unlearn it, which is why experienced graders are the scarcest resource in this industry.
