The disclosure provides a cushion including an outer cover defining an interior cavity, and inner filler material disposed within the interior cavity. The inner filler material may comprise at least one molded block of polyurethane foam. The outer cover and/or the inner filler material may be porous to at least water. The cushion further includes a waterproof coating to the outer surface the inner filler material and forming waterproof seal extending entirely thereabout after curing. The waterproof coating comprises butyl acrylate within the range of 17-32 wt %, styrene within the range of 13-26 wt %, and deionized water within the range of 42-70 wt % prior to curing. The waterproof coating may further include auxiliary components within the range of 0.5-8 wt % prior to curing. The auxiliary components may include acrylic acid, sodium lauryl sulfate, an emulsifier component, ammonium peroxydisulfate, sodium bicarbonate, sodium phosphate, tertiary and tributyl phosphate.
