Stripped Door Primer Problem

[leeds1971]

I've had some very sturdy interior doors stripped by a specialist in a warm acid bath.

They've been stood indoors for over a month now and I'm about to paint them.

The trouble is I'm applying Dulux water based primer/undercoat and in some areas the white primer goes dark and does not adhere very well to the wood. When it is fully dry a little bit of rubbing with fine sandpaper will bring the primer off, whilst other areas (that didn't go dark) are much sturdier.

Any tips on what to do?

 

[middi]

Rub down the areas in question with some fine sand paper, apply some "knotting" solution to the areas and after 24 hrs try again with the primer

Middi
Ps- what wood are the doors made out of

 

[leeds1971]

The doors are c.1840. I think they are made of pine.

Thanks for the tip. I'll try it out.