Durock is very similar to our Skeewbacker Classics. They are rectangles and squares, waterproof, rot proof, ultra lightweight, clean, and easy to work with. You can cut them with a utility knife if you like. There is no preparation, other than your hanging kit installation first, and no need to seal them.
Composition and Materials: USG Durock UltraLight Foam Tile Backerboard is composed of a rugged thermoplastic facer and backing, combined with an extruded foam core.
They are constructed from a rigid polystyrene foam core sandwiched between waterproof membranes. You can frame them, hang them, or permanently install them. If you wish to paint the edges, use appropriate paints with no solvents, as solvents will compromise the foam core center. Acrylic paints are the best. You can also put grout or thinset over the edges.