The latest buzz in the stone fabrication industry is a technique called seam polishing.  Some fabricators are offering there customers a tight smooth seam by grinding the seam down and polishing it to a factory finish. This makes for a smooth seam when you run your hand across it.  Great idea, isn’t it?  Maybe not.

I am not a fan of seam polishing for several reasons. First, face polishing is perhaps the most difficult task that a fabricator can perform.  I am not saying it is not achievable, but the problem is new fabricators or those without this skill will end up ruining a countertop.  Just ask some of the restoration guys how many countertops they are getting called on due to seam polishing attempts.  If you have the skill or the time to practice, practice, practice, then knock yourself out and go for it.

I have polished many seams in my lifetime. Many of the seams I polished were to fix someone’s mistakes when they tried to seam polish. You may also have to seam polish if you have bowed slab.  These are the only times that I would consider seam polishing.

What if I were to tell you that you can achieve a smooth, almost seamless seam with breaking out the polisher.  You can also produce the same smooth transition without the risk of seam polishing.  The following is a technique I developed that we teach in our Stone Fabrication seminars:

The most important step in obtaining a smooth tight seam is to make sure you set the countertop properly. This starts with the templating stage. The cabinets need to be as level as possible so that the stone will sit flat.  This allows each stone piece that you member up to be as level as possible so you don’t have to shim the seam.

The next most important step is when you cut  the stone on your saw. You want a smooth, clean cut with no jagged edges. This is a problem that I see in a lot of installations.  If you’re getting jagged, spalled edges than you need to take a look at your blade and the speed that you’re cutting.  Nine times out of ten you will find you’re using the wrong blade or the blade is worn out or glazed.

Now you’re ready to install the countertop.  Bring the stone in being careful not to bang the edges. I usually protect them with some low contact masking tape.

Dry set the stone and use a seam setter.  Adjust the seam so that your fingernail runs smoothly over the joint.  A good seam setter is key.  Once you have the seam where you want it, open up the seam and pour in clear flowing grade polyester.  Noticed I am not coloring the polyester. Most stones don’t need to be colored, however you may want to use some tint for darker stones such as black absolute.

Tip:  To hide the fine light colored line on the seam take a marker and color the very edge of the stone. This works great on black absolute.

Close the seam with the seam setter allowing the polyester to flow up onto the top.  This will take a little practice getting the proper amount of glue. DO NOT remove or clean the excess glue at this point. Allow the glue to dry.

Once the glue is dry, remove the seam setter.

Next, take a razor blade and shave the dried glue. Hold the razor blade straight up and perpendicular to the face of the stone.  The way you hold the blade is critical. If the blade is allowed to get under the glue it could pull it up and out of the seam.

Once the glue is scraped away you will need to take a pumice stone and rub it across the seam to smooth the joint.  A pumice stone is a volcanic stone. The beauty of a pumice stone is that it will remove the glue but will not scratch the granite.

After the entire joint is smoothed take some denatured alcohol on a rag and rub the joint to bring the color back.

This method works great and the risk of ruining the countertop is reduced.