All About Sealing Granite
No matter how much you clean your granite counters, you'll always have problems with dirt if your countertops are not properly sealed. If you've worked with a reputable kitchen designer, you'll already be aware of the importance of having your counters regularly sealed. In order to keep your counters looking their best, you should have them resealed at least every two years, but ideally yearly.
There are some misconceptions about what granite sealers do. Most of them work in the same basic way. Contrary to the common perception, they aren't a surface finish that creates a film on top of the stone that prevents physical damage and staining. Sealants actually are absorbed into the porous stone. They create a barrier that buys you time to prevent a spill from seeping into the granite, but an unattended spill can still affect the stone.
Using a good sealant will greatly extend the life of your countertops, protecting your investment and making your counters easier to clean. There's no need to be obsessive about sealing and resealing—applying more sealant to an already-sealed countertop simply results in a film on the surface that gives your counters a dull look.
How does granite sealant work?
Granite sealant is also called an “impregnator.” It's made of a resin dissolved in either water or a petroleum-based solvent. When it's applied to the porous stone surface, it initially creates a film, which then is absorbed into the stone. The resin fills those pores, and once the solvent or water evaporates from the mixture, the resin hardens, creating a barrier that helps keep dirt and liquids from seeping into the stone.
It may seem odd that stone can be stained, but all stones are porous to some degree. Some are highly absorbant, while others are very dense and almost stain-proof, but all natural stone is porous. Granite is no exception, and it's important to use a good sealant in order to prevent staining.
When sealant is properly applied, it keeps spills on the surface, allowing them to be cleaned up before they can seep into the stone and leave stains. Wine, coffee, oil, and other things all can stain granite if spills aren't cleaned up promptly, even when the granite is sealed. Unsealed granite will stain much more easily.
Keep in mind that no sealer can create a perfectly impenetrable surface. While a good application of a high-quality sealant will create a very effective barrier, it's important to clean up spills quickly, especially with liquids that are highly staining. Liquids can seep through the resin barrier, and even if deep stains are prevented, surface-level staining can still happen. Evaporation generally happens before absorption on a well-sealed counter, but oil is an exception.
Well-sealed granite also helps prevent the spread of bacteria, mold, and viruses. Unsealed granite can trap moisture and harbor bacteria in its pores, providing an environment where these microorganisms can grow. Sealant closes off those pores, creating a less-friendly environment for bacteria, viruses, and mold.
How often does granite need resealing?
Sealant is most effective when applied as needed, rather than on a prescribed schedule. Depending on the color and porosity of the stone, the quality of the previous sealer, and the degree of use, granite countertops may need to be resealed every one to five years.
If your counters see heavy use and are cleaned with harsh cleansers (which can damage the sealant and even the stone itself), you may need to reseal a couple of times a year. However, with proper cleaning, sealant can last a lot longer.
There's an easy way to see whether your counters need to be resealed: simply spill some water on them. If it beads up and stays on the surface, your counters are well-sealed. If it spreads out instead, seeming to disappear into the surface, they need to be resealed.
Another test is to lay a sponge or rag that is fully-saturated with water on the surface for a couple of minutes, then remove it and wipe up any remaining water. If the stone is darkened where the sponge or rag was placed, the stone has absorbed liquid, and needs to be resealed.
Can I seal my granite countertops myself?
While it is not difficult to apply a sealant yourself, most DIY sealant applications will not last as long as a professional job. If you want to ensure that your granite will continue to look its best without resealing for a long time, contact a professional to do the job.
Granite colors and sealant needs
Not all granite is the same. Lighter colors tend to be more porous and will need sealing more frequently. They're obviously also more likely to show stains. However, darker granite is still porous and while stains may not show, bacteria can still be harbored in the surface, and so sealing is still important.
However, there are certain varieties, like Absolute Black or Black Galaxy granite, which are very dense. These varieties are not as porous, and in fact, when sealants are used they tend to remain on the surface instead of being absorbed, leaving the stone looking hazy.
When you install granite countertops, be sure that you understand the best way to care for them. Most stone needs to be sealed, and will need occasional resealing with use. With proper care, well-sealed countertops will be easy to clean and stain-resistant. As a natural material, granite does require some maintenance to remain looking great, but it's not difficult, and the results are well worth it.