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 and Exterior Finishes - priming is critical for preventing wax bleeding. Ask your Muralo dealer for the best Muralo exterior paint for your project, in the color and sheen of your choice.