Hi, We've an old pine cupboard that's been kicking around for years
and finally trying to tidy up.

Think it probably been caustic dipped a while ago, the result being
that patches appear to be damp to the touch, spongee and a darker
brown.

Is there anything I can do to stabilise what's left?

I've already tried vinegar and washed several times with water. Some
areas now look better, but others well

Thanks, Tim.