Even though countertops made up of granites are not necessarily to be sealed, but sealing always helps to keep the countertop away from hard stains can surely defend the stone from against dirt and chemical spills that may lead to corrosion or de-colorization. Some of the liquids that can stain the light colored countertops are grape juice, red wine, cooking oil and Pizza grease.
Granite stones are by nature wetness resistant but also slightly permeable in nature. Due to the permeable nature of the granite, they are prone to slight dirt exposure. Therefore it is always advisable to use sealants to block liquids from leaching into the countertop. When a countertop is correctly sealed then it will formulate beads when any liquid is poured on to its surface.
It’s advisable to seal all granite countertops and sinks annually keeping in mind the porosity of the stone. You can find out the time when you need to reseal your countertop by sprinkling water over the countertop. When the water you sprinkle stays like beads then it means that all is fine. When the water you sprinkle is slowly spreads then it means the it’s time for some resealing works to be done for your kitchen countertops.