Why is it important to identify the epoxy coating on the surface of stone materials?

Identifying the epoxy coating on the surface of stone materials is crucial because the grinding and polishing of natural stone require working on the actual natural stone surface to be effective. If there is an epoxy coating on the stone surface, the surface material becomes resin instead of mineral, making it unsuitable for the traditional practice of grinding and polishing natural stone for restoration and maintenance.

Granite, quartzite, and engineered stone typically do not have epoxy coatings due to their uniform texture and minimal occurrence of flaws such as cracks and holes. Epoxy coatings are commonly found on surfaces made of natural marble, such as tabletops, coffee tables, and bathroom countertops. The purpose of applying epoxy is to prevent the penetration of stains into the stone and to conceal flaws like cracks and holes on the original marble surface. However, over time, this non-natural coating can yellow, crack, and deteriorate.

Simple ways to identify an epoxy coating include:

Touch the surface: If it lacks the natural coolness of stone, it may have an epoxy layer.

Observe at a low angle: Epoxy-coated surfaces may exhibit unnatural reflections, and there might be visible thin film layers or fine scratches.

Abrasion test: Use a Marble Diamond Hand Pad #2 to lightly grind an inconspicuous area. If the surface shows obvious scratches and polishing with marble polishing powder does not improve color, brightness, and may even cause haziness, it likely has an epoxy coating.