How to Seal Granite Countertops

Granite countertops are durable and require minimal maintenance. However, to keep granite stain resistant, you need to seal it periodically.

granite countertops
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Granite kitchen countertops require sealing to maintain the shine and protect it from stains.

Granite is an igneous rock, which means it was formed from molten rock material, specifically quartz, feldspar, mica, amphiboles, and other minerals. As the molten material cooled, tiny gaps formed between the individual crystals, creating pores in the rock. In granite's natural condition, it absorbs liquid through those pores.

Granite is relatively nonporous compared to other countertop materials, yet it requires a sealer to make the countertop stain-resistant. The sealer creates a barrier that prevents absorption of food and liquids.

How Frequently Should I Seal Granite?

Generally, granite countertops require an annual application of sealer. However, various factors contribute to the frequency. One factor is porosity. Lighter colored granite tends to be more porous; therefore, it may require more frequent applications. The second factor is regular wear and cleaning routines. Acidic food spills and acidic cleaning solutions (such as vinegar) gradually degrade granite sealer. In addition, food preparation zones may need sealer more frequently than a raised bar used to serve food.

The final factor is the sealer itself. Some professional grade sealers may last up to ten years. Some tips for determining types of sealers:

  • If you're installing new granite, ask the installer which sealer they use and how soon you should reapply it.
  • If you're sealing an existing granite countertop, whether using a water-based or solvent-based product, look for the active ingredient fluorocarbon aliphatic resin. Although the product will be more expensive than sealers containing siloxane and silicon, it will provide five to ten years of protection rather than six months to three years. Also, fluorocarbon aliphatic resins repel oil as well as water, so the countertop will be protected from things such as salad dressing spills and greasy pizza boxes.

Perform the Water Test

On a properly sealed granite surface, water should bead up rather than soaking into the pores. To test the surface, pour one or two tablespoons of water on the granite in different areas. After three minutes the water should still be beaded on the top instead of soaking into the granite. Check again after fifteen minutes. Is there a dark mark or ring? If so, it's time to apply a sealer.

kitchen island
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Simple maintenance keeps granite beautiful.

If you apply a sealer before it's needed, the granite isn't harmed. However, additional sealer might create a hazy film.

How to Seal Granite

Sealing granite is a simple process that protects the investment you made in your home. Regular sealing, done properly, will prevent stains and keep the natural stone looking its best.

Step 1: Gather Materials

The materials needed to seal a granite countertop are easy to obtain, but make sure you have them all on hand before you begin:

  • Microfiber cloths or clean rags
  • Granite cleaner (or make your own, using a one-pint spray bottle, liquid dishwashing detergent, and isopropyl alcohol)
  • Granite sealer
  • Rubber gloves
  • Flat utility knife (optional)
  • Extra fine steel wool (optional)
  • Granite stain remover (optional)

Step 2: Prepare the Surface

First, look for any hard water deposits near the faucet? If they are present, use a flat utility knife to cut away these mineral deposits. Apply gentle pressure and hold the blade flat against the surface; wipe the surface dry. If a small amount of mineral deposit remains, complete the task by gently rubbing it off with extra fine steel wool, then wipe with a clean, dry cloth.

Flat utility knife.
credit: Tracie Henkel
Carefully follow the curved edge of the granite while removing mineral deposits near a sink.

Next, examine the surface for stains? Purchase a granite stain remover (sometimes referred to as a poultice) and follow the manufacturer's directions. Typically, you will apply the remover and let it dry; as it dries, the remover draws out the food or liquid from the granite's pores.

As the final preparation step, clean the entire countertop 24 hours before sealing, so cleaning agents evaporate out of the pores that will need to absorb the sealant:

  1. Remove all items from the surface and wipe with a dry cloth to remove dust.
  2. Spray with either a granite cleaner or mix your own in a one-pint spray bottle. Combine one teaspoon dishwashing detergent, two tablespoons isopropyl alcohol, and enough cool water to fill the spray bottle.
  3. Spray a section of the counter and wipe the cleaner from the countertop with a clean cloth, using a circular motion. Continue the process until the entire countertop is clean.
  4. Allow the surface to dry for 24 hours.

Apply the Sealer

  1. After the 24-hour drying period, select a small test area. Follow the instructions on the sealer label.
  2. Apply the sealer and then rub it evenly on the granite with a clean cloth. (A pour bottle can be easier to control than a spray bottle. If you use a spray sealer, protect other surfaces, such as cabinets, floors, and walls.)
  3. Per the label instructions, allow the sealer to dry, usually for 15 to 20 minutes. If the area is discolored, remove the remaining sealer and consult a store associate who sold the product. If the surface looks great, continue applying the sealer, working in sections, until you've applied sealer to the entire surface.
  4. Wait for the recommended absorption period and then wipe off any excess sealer with a clean, dry cloth. Follow with a second coat if recommended by the manufacturer.
  5. Allow the sealer to cure for 48 hours before returning items to the counter or allowing the counter to get wet.

After Care

Maintain the countertop by wiping up spills as they occur with soapy water and then drying the surface. Use the remaining granite cleaner on a monthly basis to keep the countertop looking like new.