Most granite is very stain resistant and does not “require” sealing. However, sealing is an added precaution, and many fabricators and installers do recommend it. Quality Granite & Marble typically makes this determination, and applies sealer when needed.
A general rule used when manufacturing is, if water darkens the stone, it needs a sealer.
It’s important to know a little about the granite slab fabrication process before sealing. Resin coating applies an epoxy over the stone slabs. This resin fills the voids, veins, and fissures. This process was developed to make unstable stone sellable. The more the process was used, the more common it became. Many fabricators simply apply resin coating to all slabs to keep things simple. When you mix a sealer with an unknown resin, it may turn the resin cloudy. This is one reason you may not want to blindly apply a sealer. Check with your installer first.
For stones that do require, or would benefit from, sealing, there are a few variables to considers when determining how often new sealer is needed.
- How much abuse the countertop gets
- How often the granite is cleaned
- How absorbent (porous) the natural stone is
- The type and quality of the previous sealer used
Many sealers applied at the factory last 10-15 years, while store bought (DIY) sealers may only be good for 6-12 months. So it’s important to know if you had a sealer before, and what type.
A simple water test will help you determine if sealer is needed. Pour about a quarter cup of water on a few areas of the counter. See how long it takes for the water to absorb. If the water absorbs into the stone in less than five minutes, the stone does need to be sealed. If the water is still standing after 30 minutes, no sealer is needed. Anywhere in between five and 30 minutes, the stone may benefit a sealer.
Sealing granite is a relatively simple process and can be done by a professional or by homeowners. Before sealing, it is important to know the makeup of your stone, so check with your fabricator and/or installation documentation to make sure you select the correct product and sealing process.