Stains that come from waxy substance in the reconstituted wood products used to make hardboard siding. When the substrate is painted, these staining substances bleed through the paint; they can even bleed through some ordinary primers, possibly causing dirt pickup, mildew and/or poor paint adhesion (see Dirt Pickup and Mildew).
- Failure to apply a proper primer to hardboard before applying the top coat.
- Allowing hardboard siding to weather before being painted.
- To treat or prevent, apply a quality exterior acrylic latex primer; follow with a coat of high quality exterior acrylic latex paint.
- The American Hardboard Association recommends two coat of top quality acrylic exterior house paint for best results.
- Some hardboard grades have adequate factory primer and need only a quality paint applied. Low quality, highly pigmented flat paints are more prone to wax bleed than are higher quality paints.
Note: Images & information provided by The Rohm & Hass Paint Quality Institute.