A composite granite sink is a sink manufactured for residential use that is a mix of granite (quartz) and resin, usually acrylic, to product a sink with color. They can be a beautiful part of your new kitchen.
There are a number of sinks on the market being sold as composite granite. The amount of granite and the amount of the acrylic in the mix varies by manufacturer from 70% to 80% granite or quartz by weight. The fact that the percentage is by weight makes them much lighter than if they were solid granite. Composite sinks are also uniform solid color and will not match the grain or pattern in granite or other countertops.
These sinks have developed quickly with a number of manufacturers jumped into the market, both known brands and cheap look-a-likes.
There are several problems with these sinks that have come to light. They are rigid and easily damaged in shipping particularly when boxed and shipped individually. Much of this issue has been addressed recently through advances in packaging. Some of the brands have trouble with fading due to RV rays from the sun. This is particularly apparent in the darker colors such as black. The sink will look dull or even dusty over time. We have heard reports of staining on the lighter colors in some brands and just recently one of our customers reported they as seeing spalling on the bottoms of older sinks.
If you decide that a composite granite sink is for you select one from a source you trust to avoid future issues.