The word 'solid' as used herein applies only to materials which are not sponge-like and which are nonyielding to handling pressure. In square or rectangular shapes, not bent, faced with plastic sheet or film. Applies on board made of vegetable, wood or mineral fiber, separate or combined with mineral filler. Board may be plain, grooved, needled, embossed or otherwise surface textured and may be perforated with holes not exceeding 9/32 inch. Slots may be provided for the passage of air. Edges may be beveled or tongue-and-grooved, and boards may be equipped with holes for fasteners. Surfaces may also be painted or printed. In boxes or crates.