No need to bathe/soak it. Working one side at a time, pour about a tablespoon of mineral oil on the board and use a lint free cloth (I use cut up t-shirts) to rub it in with the grain. Let sit for 15-30 min, repeat 2-3 times. Flip and do the other side.
Btw, here’s a thread with pre- & post-scrub photos of GF-engraved bamboo…
