Gary Lonnen from the Dulux Decorator Centre in Torrox Costa provides further solutions to staining/discolouration of paint on wood.
Cause 1
It may be caused by rust from old nails in the wood.
Solution
Rub down to remove the rust and prime any exposed metal with Dulux metal primer or Dulux QD metal primer before re-painting.
Cause 2
It may be caused by resin bleeding from knots in the wood.
Solution
Remove resin with white spirit.
Seal knots with Dulux white knotting solution and re-paint.
Resin bleeding and staining will be reduced but may not be totally prevented by the use of knotting solution.
Cause 3
Discolouration or yellowing with age occurs in all solvent based products such as gloss.
It will be more noticeable with white or pastel shades.
A common cause is tobacco tar deposits from cigarette smoke or lack of natural daylight.
Solution
Wash the surface thouroughly with sugar soap solution.
Rince with clean water and allow to dry before re-painting.
Wood that appears to be dirty particularly around glazing rebates is likely to be affected by some form of fungal growth.
The surface should be cleaned and treated with a solution of domestic bleach prior to painting.
