Sealing granite countertops critical

Dear Tim: I’ve talked to three different people about granite sealers and have received three different answers. I’m hoping you can set me straight about if granite needs to be sealed, when it should happen, how it is done and how frequently. The house I just purchased has granite countertops that are in great shape, and I want to keep them that way. – Jenifer L., Antioch, Ill.

Dear Jenifer: It is really discouraging to get different answers from different people, but in this case, much of what you were told might be true. Granite countertop sealers can be as varied as cars on a used-car lot. Add that to the different types, colors and grain sizes of granite, and you have a recipe for granite-sealing information gumbo.

First let’s talk about granite and why it should be sealed. I knew my college degree in geology would pay off one day. The granite used for your countertops is a natural stone made up of different interlocking mineral crystals. The mineralogy is vastly different from one variety of granite to the next. This difference produces granite’s nearly infinite ranges of color, crystal size and porosity.

Furthermore, some granite varieties have very small cracks in them from natural stresses exerted on the stone when it was still part of a mountain. Colored fruit juices, cooking oils, grease, fats, marker pens and anything that has color in it can seep into these small fissures, resulting in discoloration that can be very difficult to remove. Sealers act like a shield to prevent stains from entering the granite in the first place.

Granite should be sealed before it is put into use, but not necessarily the day it is installed. There should be very little airborne dust when granite sealers are applied to the stone’s polished surfaces. This means that in new construction and remodeling jobs, it is best to wait until the end of the job, after the final cleaning has taken place. Someone should seal the granite the day after the cleaning crew leaves and just before the homeowner takes possession of the kitchen, bathroom or wet bar where the granite tops are installed.

Now, that being said, there are small areas of the granite that should be sealed just after the granite is installed. It’s a very good idea to apply a sealer to areas where faucets, sinks and cooktops will be installed on or under the granite.

Faucets, cooktops and overmount sinks hide small areas of granite that can be still be attacked by liquids that might seep under a seal. Apply the granite sealer to the polished surface of the granite as well as the rough-cut holes and edges where these different fixtures will be installed.

If you are moving into a previously owned home that has granite countertops, you have no clue if they were sealed and, more important, if they were sealed with a high-quality sealer. If I were you, I would assume that the granite was not sealed and would seal it on move-in day.