However, experts will point out that no resin should be on the surface of the slab, but rather only in the cracks and the pits.
An additional problem is with profiles. Several fabricators have had experiences with the profiled edge turning out lighter than the rest of the stone. This is because the resin darkens the top of the slabs, but not the inside, where the resin hasn't penetrated.
Over time, the edge will darken and match the face of the stone. A quick fix to this problem, is to use a color enhancer to darken the edge.
2. Sealer interaction
Our technical hotline has received several calls about applying impregnators to a resined stone only to find that the material clouds, discolors or fades. After testing several slabs and sealers, I discovered that some solvent-based impregnators react with the resin, causing it to break down and turn color, cloud or fade. This is difficult to repair. The application of a color enhancer will sometimes hide this problem. I recommend using only water-based impregnators on resined slabs. Not all sealers cause this problem. Resining is a man-made process and there are bad resins and improper applications of them. So sealer is not always to blame.
3. Polishing and refinishing problems
In a recent countertop repair seminar, one student brought in some resined stone to refinish and polish. This material had such a heavy application of resin that when honing the top, the resin became gummy. Once the surface was cut and polished, it was difficult to match the stone's remaining surface. As of this writing, I have yet to find a solution to this problem other than to refinish and polish the entire slab.
Some of these problems may be from improper application and not the resin itself. Just like any other industry, quality control can be an issue, and sometimes a slab or two may slip by. This is why it's important to deal with reputable slab distributors and carefully inspect slabs upon delivery.
Only time and history will tell if the resin process is good, bad or ugly. Of course, resin chemistry and the application process will most likely improve. In the meantime, stone fabricators should be aware of these issues and learn to deal with them.