Caulking at Sink Perimeter

by Pierre Hannon Owner/operator

At the end of the installation of a stone kitchen counter top, there are always two very important operations that need to be accomplished with extreme care:

  1. Sealing of the granite, marble, or limestone with the best sealer available.
  2. Caulking of the sink with an acrylic or a silicone base caulk.

In this article, we are going to talk mainly about the caulking because many people do not perceive what can happen if the caulking at the sink has not been done correctly or if the caulk, after a while has dried up and the water has infiltrated between the stone and the edge of the sink.

Every month, we receive calls from customers who experience cracks in the front part of their kitchen stone counter top and sometimes in the back side of the sink. Those problems generally happen with standard undermount sinks where there is always two weak strips of stone, one at the front and another one at the back where the faucets are installed.

Sometimes, the cracks are very thin when the customers call us at the beginning of the cracking process. Very often they have waited a long time and the fissures are very serious (1/8” to 3/16” wide and 30” long).

The reason why the pieces of stone experience cracks is because of defective caulking in the front or at the back of the sink. We need to explain that generally, the stone fabricator had to reinforce the weakest sides of the opening with steel rods.To minimize the risks of breakage during the transport and the installation, they make one or two grooves in the non-finished side of the stone and they embed thin steel rods with epoxy resin. The steel rods are usually about 3 feet long.  

If the caulking at the perimeter of the sink has openings or cracks, (mainly due to shrinkage), the water will eventually infiltrate and reach the stone in the steel rods areas.

After a while, the rust will expand around the rods and push the stone in all directions and cause cracks that will become bigger and bigger with the time.

Eco Stone Care repairs these problems.

In the majority of the cases, the cracks are not too wide and we pour rust inhibitor to slow down the rusting phenomenon, then we dry the damaged area with acetone and with a strong professional hot air dryer.

After that, we apply fluid colored epoxy resin in the cracks to match the colors of the stone and we refinish the surfaces with special hard backing diamond pads.

Sometimes, when we can find a spare piece of stone similar to the one used for the counter top, we make two sharp cuts with thin diamond blades, remove the damaged part, rebuild a matching piece at the shop, and then we meticulously install it.

And of course, we re-caulk very carefully the areas between the sink and the stone.