Resined natural stone is stone that is treated to improve minor naturally occurring flaws. Resining is achieved by drying unpolished slabs, spraying them with polyester, and placing the slabs in a vacuum chamber that sucks the resin deep into the stone. Once the stone has cured, it can be polished to any type of finish, from soft matte to a highly reflective polish.
Natural stone has inherent imperfections, such as porosity, fissures, pitting, and the like. Resin fills, reinforces, and strengthens the durability of natural stone. According to Fred Hueston, Chief Technical Director for Stone and Tile PROS, some granites probably would not make it into the United States if it were not for the resining process, because the stone is so brittle, it would break during shipping. However, Hueston warns, "Resin strengthens the stone temporarily, but any time we introduce a man-made process into a natural material, things can go wrong. It might not be cured properly. It might not be dried properly. Polyester can become discolored when exposed to UV light."
Fortunately, problems with resined stone can be resolved. For example, polyester resin can darken on the surface of a slab (which might not be noticeable, if it were not for polished edges revealing the true color of the stone). A trained, reputable natural stone restoration contractor can apply a high-quality color enhancer to achieve a uniform color, as well as repair and restore the like-new finish to unsightly stone.