Granite is one of the hardest materials this planet has to offer, and when it is sealed, it is heat, water, scratch, and stain resistant. Some manufacturers seal granite before selling it, and some of these sealers can last ten years or more. If you receive a granite that is not sealed, or is in need of resealing, it is important to complete the task as soon as possible to avoid any damage to the stone. Luckily, sealing granite is fairly easy to do, and with the right product, is something you won't have to do very often.
To determine if your granite needs to be sealed, find a spot somewhat out of the way, like in a corner. Put a drop of water in one spot and a drop of oil a few inches away. Walk away for a few minutes, and then check to see if the water and oil have been absorbed and left a dark spot in the granite. If the drops have been absorbed, the granite is in need of resealing. If they are still resting on the surface, you do not need to seal it and can do this test again in a year or so.
Double-sealing, or sealing after your countertop passes the water and oil drop test, will not add any extra protection and may create a cloudy look, so be sure to only seal granite when it is needed.
If you have discovered that your countertop needs to be sealed, you can choose from either a water based sealant or an oil based sealant. The water based products are more eco-friendly, but the oil-based ones penetrate deeper into the granite. Either way, the most important active ingredient in your granite sealer is fluorocarbon aliphatic resin. This ingredient will protect your stone for about 5-10 years, while less expensive sealers made with siloxane or silicon as the main ingredient will only last 6 months to 1 year.
A full day before sealing your granite, clear the countertops and clean with a mixture of water, dish soap, and alcohol and wipe with a microfiber cloth. Let it dry a full 24 hours before applying the sealer. Apply the sealer with a rag using a circular motion. Follow the instructions on the label, which will usually require about 15 minutes for the sealer to set before you can wipe clean the excess. Some products need two coats, so be sure to follow the instructions for time between coats as well. Let the countertops cure for 48 hours before resetting your belongings on them or applying anything wet to the surface.
Sealing your own countertops is an inexpensive and easy way to keep your investment in stone surfaces looking like new for decades to come. While it does take a few days to seal it, most of it is hands-off and is very much worth the wait. Spend a little extra on a sealer, and you will only have to seal it after 5-10 years. To know if it is time to seal again, do the water and oil droplet test and see if your countertop is still repelling both substances or absorbing them. Remember, a well-cared for a regularly sealed granite countertop will be sure to last a lifetime of gatherings.