How can I avoid stains or discolorations bleeding through paint surfaces?

Common causes of bleeding from the surface below include old wallcoverings, bituminous paint and creosoted surfaces, so these should be completely removed before painting. If this is not possible apply one or, in severe cases, two coats of Dulux Trade Aluminium Wood Primer. New creosote or bituminous materials must be aged for at least 12 months before painting. For staining by metallic inks in wallcoverings or felt tip pens, the surface should be touched in locally with Dulux Trade Alkali Resisting Primer.