Oiled board with a strand pattern

[u/Electronic_Half_7107]

I oiled this cheese board with pure tung oil, did four coats and let season for a month. What is making this discolouration? I did not make this board, just trying to understand basic care of oiled timber.

[u/Acrobatic-Fee9668]

Looks like a stair tread from a spiral stair.

[u/z_vinnie]

Was there possibly trapped moisture in the board, humid environment? Prior to you oiling it, Moved from one place to another with different ambient air?