How to Seal Granite Countertops

  • July 26, 2019
  • / By Dale Keese
Kitchen with Granite Countertops

Granite is one of the hardest natural stones. It has a high weight limit and can withstand extreme temperatures. It’s also resistant to water seepage to a certain extent. These characteristics make granite a popular choice for kitchen countertops and bathroom countertops. In the kitchen, the countertops are exposed to oil spills, food, or acidic substances, along with hot utensils being placed on it. In the bathroom, it’s exposed to excessive water spills and chemical cleaning fluids.

Kitchen with Granite Countertops

Unlike marble or limestone, granite has very low porosity. If water is left on a granite countertop, it will take a long time before any of it is absorbed. But oil-based spills are a different matter. These will stain the granite surface. And acidic substances such as citrus fruits, vinegar, citrus-based cleaning products will cause etching. While etching is not completely avoidable, you can do something about staining by applying a good quality granite sealer.

A granite sealer or a natural stone sealer will block the pores inside granite and prevent any stain producing substances from seeping in. Instead, these substances will bead on the granite surface, making it really easy to clean up. Coffee, wine, juices, cooking oil, and grease can all stain or discolor granite countertops.

Before we can get down to how to seal granite countertops, it’s important that you understand which type of granite sealer to use. Penetrating sealers are the best for granite. It’s absorbed deep into the granite and provides protection against the toughest oil-based and water-based stains. Penetrating sealers do not alter the natural color or appearance of the granite, which is equally important.

Granite is an expensive stone and you don’t want to spoil the look you paid for by using a topical sealer. Water-based penetrating sealers are safer and easier to apply. These are the ideal choice for indoor usage because these don’t have an unpleasant odor or release harmful fumes. But some solvent-based penetrating sealers enter deeper into the granite and provide greater protection, especially against oil-based stains.

Carbon resin sealers provide the best results, especially the fluorocarbon aliphatic resin-based sealers. These are without a doubt the most expensive variety of granite sealers, but these last the longest as well. You won't have to worry have re-applying the sealer for a minimum of 5 years or more.

You can also opt for siloxane or silane-based sealers. These aren't as good as the fluorocarbon aliphatic resin in resisting oil-based stains, but provide good protection to granite countertops nonetheless. You should avoid silicone-based sealers because these need to be reapplied every 6 to 12 months. Plus, the level of protection is lower as well.

You should first perform a water test to check if you should at all seal granite countertops at your home before you learn how to seal granite countertops.

Water
  1. 1
    To perform a water test, pour about 1/4th cup of water on the granite countertop.
  2. 2
    Mark the time when you poured the water.
  3. 3
    Wait to see how long it takes for the granite to absorb the water.
  4. 4
    If the water is absorbed immediately, you will need to seal the countertop with a top-quality sealer. You should apply at least two coats of the sealer and you should re-apply the sealer once every 12 months.
  5. 5
    If the water is absorbed in about 5 minutes, you will have to seal the countertop, but there’s no need to re-apply it before 3 to 5 years. You should perform this water test once again, before reapplying it in the future.
  6. 6
    If the water absorbs in about 10 minutes, a single coat of a high-quality granite sealer will suffice. If you clean and take proper care of the granite countertop, you won’t have to re-apply the sealer for a long time.
  7. 7
    If it takes 30 minutes or more for the water to be absorbed by the granite surface or it doesn’t absorb at all, there’s no need to seal the granite countertop. As mentioned earlier, a penetrating sealer must be absorbed by the granite to be effective. If the granite is so dense that it doesn’t absorb anything, it means it’s stain-resistant and doesn’t require a sealer. If you still apply a sealer, it will remain on the surface in the form of an ugly, hazy film.

For kitchen countertops, which will undoubtedly be exposed to oil and grease, carry out the same test with a few drops of oil as well. This will not only help you determine if the countertops need to be sealed or not, but it will also help identify the right sealer. If the oil drops are absorbed in under 10 minutes, you will need a sealer that’s particularly good at resisting oil-based stains.

Granite Stones

Sealing a Granite Countertop

Step 1: Clean the Granite Countertop

Thoroughly cleaning the countertop before applying the sealer is as important as the water test and the first step of sealing granite countertops. You should clean the countertop 24 hours prior to applying the sealer. Ideally, you should use a specialized granite cleaner for this. If you don’t have that, you can use non-acidic liquid soap to clean the countertop. Using an acidic cleaning product might result in etching, which will spoil the natural look of granite.

Begin by wiping the countertop with a microfiber towel or cloth to remove any dirt and grime. Next, either spray some granite cleaner on the surface or mix a teaspoon of liquid soap in water and spray it on the countertop. Wipe it clean with a fresh microfiber towel.

Mix isopropyl alcohol in water and spray this mixture on the countertop. This will act as a degreasing agent and remove any oily or greasy residue from the countertop surface. Wipe it clean with a microfiber cloth. Now let the countertop rest for 24 hours and become completely dry. This thorough cleaning will ensure that no contaminant gets trapped in the surface when the sealer is applied.

Step 2: Test the Sealer

Testing at each stage is an important aspect of how to seal granite countertops. You should test the sealer in a nondescript corner of the countertop, before applying it on the entire surface. If the sealer discolors the granite or forms hazy residue, it means the sealer isn’t compatible with the granite. You will have to pick a different sealer.

Do not forget to give the sealant enough time to be absorbed into the granite. The recommended wait period will be mentioned on the container. If you don’t give it enough time, you won’t know the actual reaction. If you leave it on the surface longer than recommended, the granite might get discolored. Usually, the wait time is 10 to 15 minutes.

Step 3: When in Doubt, Follow the Manufacturer’s Instructions

Typically, the sealer container or bottle will have an instructions label, including precautionary measures, safety measures and more. Read and understand these instructions. If there’s any conflict between our instructions and those provided by the manufacturer, then go with the manufacturer’s application method. Test the sealer (Step 2) per the manufacturer’s instructions as well.

Step 4: Apply the Sealer Evenly

Spray the sealer evenly over the granite countertop. Alternatively, pour some of the sealer on a lint-free cloth and apply it evenly over the surface. Start from one edge or the end of the countertop and use a circular motion while applying it. Now, wait for the recommended period of time to allow the sealer to soak into the granite. This period of time varies from sealer to sealer, but usually, it’s in the 10 to 20 minutes range.

Bathroom Counter

Step 5: Clean Excess Sealer and Apply a Second Coat

There’s a chance that after the sealer saturates the granite pores, some of it may remain unused on the surface. This excess sealer should be cleaned up as soon as the recommended wait or absorption period is over. Leaving the excess sealer on the granite countertop can result in discoloration or residual streaks and marks. On the other hand, if all of the sealant has been absorbed, it might be an indication that a second coat is required. Typically, granite doesn’t require more than one coat of a good quality sealer.

Step 6: Curing Time

The curing time is the time required by the sealing polymers in the sealant to properly bond with the granite molecules and for the anti-stain anti-spill effect of the sealant to become fully potent. Even if the manufacturer recommends a lower curing time, it’s advisable that you leave the countertop undisturbed for at least 24 hours and if possible 48 hours. During this period do not touch the granite surface or place any objects on it.

Step 7: Final Clean

Once the curing time is over and before you can start using the granite countertop, a final clean up is required. It will remove any remaining sealant residue. Use the same liquid soap and water mixture you had used earlier and microfiber cloth to properly clean the countertop.

Remember that even though the sealant is there to protect the granite from stains caused by spills, it’s best if you clean up any spills as soon as possible. Also, keep a bottle of granite cleaner handy in the kitchen or bathroom, along with a microfiber cloth for periodic cleans. It will increase the lifespan of the sealant and the granite countertop.

Wine Rack on Counter

Precautions

There are few precautionary measures you need to keep in mind while sealing a granite countertop.

  • Wear a pair of good quality gloves while applying the sealer.
  • If you’re using a solvent-based sealer inside the house, then make sure the room is well ventilated. Once the sealer begins to dry it will release toxic vapors, with an extremely unpleasant odor. If the room in question doesn’t have proper ventilation options, then keep the doors and windows in the adjacent rooms open to allow for cross ventilation.
  • The sealer you use for kitchen countertops should be safe for food preparation areas. This is usually mentioned on the label itself.
  • No sealer, not even the most expensive ones, can protect granite surfaces from etching if it comes in contact with acidic substances.

Conclusion

Granite countertops can cost anywhere between $50 per square foot and $150 per square foot, depending on the type of countertop, the granite design, etc. So, you should take care of it and provide it with whatever protection you can. A good quality sealer will help you maintain the natural look and color of the granite for a longer period of time as well as prevent staining.