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, IL
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 size of granite, and you have a recipe for granite-sealing information gumbo soup.
Let's first 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 granite to granite. This difference produces the nearly infinite color ranges of granite, the size of the crystals and the porosity of the stone.
Furthermore, some granites have very small cracks in them from natural stresses that happened while the granite 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 and cracks. The resulting discoloration 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. This doesn't mean the day it is installed. Granite sealers should be applied to the polished surfaces of the granite when there is very little airborne dust. 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, with that being said, there are small areas of the granite that should be sealed just after the granite is installed. It is a great idea to apply a sealer to the areas immediately adjacent to 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 importantly, if they were sealed with a high-quality sealer. If I were you, I would take the position that the granite was not sealed and do so on move-in day. I realize you will be very busy moving in, but you will regret sealing the granite if someone spills grape juice or leaves a greasy pizza box sitting on the countertops as you collapse from all of the work on move-in day.
High-quality granite sealers have a long life span. Some can provide protection for up to ten years. The life expectancy of the sealer you purchase should be clearly marked on the product label. To be safe, I would not wait until the old sealer wears off before applying additional coats.
Granite sealers are easy to work with. As with any specialty product, always read the application instructions, and follow them to the letter. Many granite sealers tell you to apply them to dry granite. This is very important. Be aware of what dry means. This doesn't mean clean the countertop and then dry it with a paper towel. Water from the cleaning process can seep into the granite just as a liquid that might stain it. If water is in the small cracks, fissures and spaces between the crystals, the sealer can't penetrate into the granite.
Clean the granite and let it sit for 24 hours or allow a fan to blow across the granite for eight hours. Wet granite has a richer color than dry granite, so wait for the granite to get that faded look before opening the sealer.
Once the sealer is dry, buff it with an old terry-cloth bath towel. These rough cloths do a fantastic job of making the granite shine. Do not use a mechanical buffer unless you know what you are doing. You can ruin the granite in short order. If you do use a buffing machine, make sure it is an orbital one just like the ones used by auto-body repair shops.