Hardboard:
Wood pulp fibers and binders are formed under extreme pressure and heat. These products can be susceptible to moisture.
Although you can draw or paint directly on the hardboard panel with oils and dry drawing media, we recommend a barrier for most applications.
When painting with any acrylic paint, medium, gesso, or ground, we recommend applying 2 or more coats of Gloss Medium first to reduce support induced discoloration.
For oils, apply 3 or more coats of Acrylic Gesso or Fluid Matte Medium to reduce oil absorption.
Grounds (including those for drawing media and watercolors), gels, and pastes can be applied to alter the surface’s absorbency, durability, or texture.
Video: Support Induced Discoloration (SID)
Article: Understanding Wood Supports for Art a Brief History
