How to properly cut a countertop for an undermount sink

I have over 50 years of experience in this arena, and there always seem to be differing opinions on how a countertop should be cut around a kitchen sink. Often, countertop fabricators insist on having a reveal or slight overhang of the countertop around an undermount sink. However, for most undermount installations, a flush cut is the better choice. Here are two common justifications I have heard for not cutting the countertop flush:

1. If the counter slightly overhangs the sink, you will not see the grout line, and the water will drip straight into the bowl.  My comment: This type of installation will require more maintenance to keep the underside of the overhang clean. First of all, water will not fall straight down from the countertop overhang. As the water slows down, the water will pull under the overhang, and it will become a breeding ground for bacteria, mold, and mildew.

2. Having a reveal makes the sink easier to clean. My comment: The revealed flange will now have water and debris sitting on the grout line, causing degradation of the caulk.  What you see below is a common solution for many luxury brands. They use the flange as a top tier. When the flange is used as a top tier, and water sits at the grout line. You can even see the dirt and mold growing in the caulk line in the below image!  The exposed flange can collect dirt and grime, requiring regular cleaning. If you zoom in on this photo, you can see the mold in the grout.

Using a flange as a top tier in a workstation sink is a breeding ground for trouble!

The proper way is to have a flush cut. In my opinion, this is the most difficult to cut. It requires extreme precision. This is especially important for workstation sinks. because an improperly cut countertop may prevent the accessories from fitting properly. The precision aspect is why I think some companies shy away from this method. I have researched this quite a bit online, and most professionals indicate a flush cut is the proper way to cut a countertop for most sinks. Water will drop straight into the bowl and help keep the grout clean. Take a look at the short video below for more details.