Seams are very important in fabricating stone countertops; they hold it all together. It can make a difference — sometimes a big one — in terms of seam placement, adhesive and in the overall look of the top. Since the goal we all share is to put out a countertop the customer will love, the following are some frequent questions I get asked in regard to seaming those tops.
Q. Dear Fred, we have been having a running argument with our installers as to the proper type or consistency of glue to use in our seams. One of our teams insists on using knife grade poly and the other insists on using flow grade. Which is the proper consistency to use?
A. Your answer should be simple to solve. Just go look at their work. I bet you find the team using the flowing grade has tighter seams. This is not to say that knife grade is not proper either, but look at it this way: If their seams are very tight, it is going to be nearly impossible to use knife grade since it won’t fit in the seam. This is the reason some installers leave a little bit of a seam so they can use the knife grade. On the other hand, flowing grade can be tricky since it will require that you tape the bottom of the seam so it does not run through. They are both acceptable glues depending on your standard for seam width. Here is a tip that I have used in cases where the knife grade is too thick and the flowing is too thin. Mix the two together to get an in-between consistency.
Q. Dear Fred, when we install some of the darker granites like black absolute and some of the black engineered stones, we can see a fine white line in our seam. We have tried darkening the glue but we still get that same white line. Any tricks or tips as to how to eliminate it?
A. This is a common problem with many of the dark stones and engineered stones since the cut edges are lighter than the polished faces. The simplest solution is to take a black felt marker and mark the edge before you apply the glue and fit the seam.