Protek Stain Blocking Primer is effective at blocking tannins, pressure treatment chemicals and rust (from nail heads) bleeding through to the top coat.
We would recommend using this primer when white or light colours are used as a topcoat to stop any unsightly yellow staining coming through from the wood. This is not usually an issue with natural wood colours so it is not necessary to use this primer with them. Please note that if the timber is resinous a knotting agent should still be applied to the knots.
For use on all outside wood that is not in direct contact to soil or surface water..