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. Use Hirshfieldís 6050 Exterior Oil Primer or 4250 Housecoat Acrylic Primer. Finish with a top quality 100% acrylic exterior latex paint in the color and sheen of your choice like Hirshfieldís Housecoat series.