Tape test
You can check the wood surface by carrying out a tape test, when the wood is dry. This is what you do: Take 30 cm of tape. Place the 20 cm on the wood and use the last 10 cm to hold the tape. Rub the tape thoroughly against the wood with your nails and leave it for one minute:
Make sure you rub the tape well onto the wood surface.
Tear off the tape in one quick movement. If there are wood fibres on the back of the tape, the wood has not been cleaned or sanded sufficiently:
There are many loos wood fibres on the tape. This wooden surface has not been cleaned or planed sufficiently.