Wax bleeding: Migration of waxy additives used in reconstituted wood products to the surface causing discoloration and possible wetting.
Probable causes: Exposing the hardboard to weather too long before painting. Not priming or using an improper primer. Dark colors are more prone to wax bleeding because of heat absorption. Inadequate paint film thickness. Flat paints are more likely to wax bleed.
Wax bleeding solutions: Prevent the wax used in hardboard manufacturing from bleeding by painting new hardboard within 30 days. Hardboard siding needs 3 coats: primer and 2 finish coats. Use a recommended primer before repainting. Wax bleeding avoidance reduces dirt adherence.
Primers & exterior finishes: Priming is critical for preventing wax bleeding. Select a top quality exterior paint in the color/sheen of your choice.