How to Seal Granite and Marble Countertops

Table of Contents

• Why Seal Granite & Marble Countertops?
• When Not To Seal Natural Stone Countertops
• How to Seal a Marble or Granite Countertop
• Guidelines for Properly Sealing Granite Countertops
• What to Use for Sealing Granite Countertops
• Guidelines for Sealing Marble Countertops
• What to Use for Sealing Marble Countertops
• How Often Should You Reseal Your Countertops?
• How to Maintain Your Sealed Surfaces

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Besides countertop care and maintenance, one of the most common questions we hear is whether natural stone countertops need to be sealed. Ask three people whether you should seal granite countertops, and you’ll get three different answers. There’s a good reason for this range of opinions. Not all stone countertops need to be sealed. Some types of granite, like Ubatuba granite, for instance, are so dense that they won’t absorb anything. It has a very low absorption rate and a low chance of staining.

However, the vast majority of natural stone countertops need to be sealed once in a while. This is true of counters with a honed finish. Sealant keeps these stones resistant to stains and makes it easier to keep the kitchen countertop clean and looking good.

Why Seal Granite and Marble Countertops

Properly sealing natural stone is important because most stones are porous. Quartz, which is engineered from natural stone, is the exception to this rule. Porous stones have small channels or pores in the rock, which are usually filled with air. An extreme example of a porous rock is pumice stone, where air channels are clearly visible.

Although granite and marble are considered hard stones, they both contain tiny pores and capillaries within their structure. These microscopic openings can easily absorb liquids, such as coffee or cooking oils, making stains difficult to remove. Marble is more porous than granite, making it more prone to damage from acidic substances like lemon juice or vinegar. Even water rings or oil from cooking can darken spots on untreated countertops.

Applying a quality sealer creates a protective barrier within the stone’s pores. Liquids remain on the surface longer, giving you time to wipe them away. The stone is also better shielded against dull spots and staining. Sealing helps maintain the rich color and natural patterns of granite and marble, keeping your countertops looking as elegant as the day they were installed.

When Not to Seal Natural Stone Countertops

There are some types of natural stone that don’t need to be sealed. These include quartz counters, tables, and kitchen islands. Although quartz is made from natural stone, it’s combined with a resin in the engineering process. This resin means you won’t need to seal quartz. In fact, sealing quartz surfaces can actually leave them with a hazy film. Dense granites are another type of natural stone that doesn’t always need to be sealed. Sealing travertine, limestone, and some marble is recommended more for cosmetic reasons than for protective ones.

 

How to Seal a Marble or Granite Countertop: A Step-by-Step Guide

Sealing granite, marble, or natural stone countertops is a relatively easy home improvement process that usually takes less than an hour. While each material has its own unique requirements, these are the general steps to follow:

1. Properly Clean the Stone

Cleaning the counter thoroughly helps the sealant absorb evenly. Remove any stains as part of this cleaning process. The sealant will lock in stains, which you want to avoid. Start by identifying the source of the stain. This will help you to treat it properly. The Natural Stone Institute provides a detailed list of stains on natural stone, and how to remove them.

There are several recipes for DIY granite and natural stone cleaners, and a wide variety of natural stone cleaners available in stores. You’ll also find specific recommendations below. After cleaning, dry the counter thoroughly. If you are unsure whether the stone is completely dry, err on the side of caution. Sealers require dry stone to perform effectively.

2. Carefully Apply Sealant to the Countertop

The application of any sealer should align with the manufacturer’s instructions. Some manufacturers provide specific techniques and sealer amounts required for various stone types and finishes, such as polished, honed, or flamed. Some companies will recommend one coat, and others may recommend two or more — read the directions and inquire with a representative for further clarity.

These tips will help you achieve optimal results with any sealant:

• Prepare the area: Cover any surfaces you don’t want sealant on. Use plastic wrap to protect faucets, sinks, and stovetops. Protect backsplashes and walls while you seal. Grab a magazine — or any other thin material you don’t mind getting sealant on — and place it along the seam between the wall and the kitchen countertop.
• Start with a test: Always test the product on a small area and wait 24 hours for the desired results.
• Follow instructions closely: When you use homemade sealers, mix the ingredients together well by shaking the spray bottle before use. With commercial sealers, follow the mixing instructions. Apply the proper quantity of sealer, and be sure to allow for the recommended dwell times between coats.
• Apply sealant carefully: Always use a soft cloth, lambs wool, or soft brush to apply sealant. Start in a small area — since it doesn’t stay on the counter for long, this will allow you to wipe it off when needed. Once you’ve sprayed the counter, leave the sealant for approximately five minutes to allow it to soak into the stone. If the stone sealer you’re using specifies a different length of time, follow those recommendations.

3. Remove Excess Sealer

Some of the sealant will be absorbed by the stone itself. However, once a stone is sealed, there’s usually a bit of excess left on the surface. Use a soft cloth to wipe up any excess product. We like microfiber cloths for this purpose. They’ll soak up leftover sealer without leaving fiber on the counter. Do not let the sealant dry on the counter.

In some cases, you won’t have any sealer to remove. This means that the sealer has been fully absorbed by the stone, and it’s possible that the perfect amount of sealer has been applied. It is always advised that the stone be thoroughly wiped down after the final application. In the event you notice any residue, most manufacturers recommend using the sealer itself to re-activate and wipe off any excess.

However, your natural stone counters likely need another coating of sealer. If this is the case, proceed to step four.

4. Apply Additional Coats of Sealant As Needed

Applying more than one coat of sealer is normal and is often recommended to ensure even coverage. The more porous the stone, the more likely you’ll need to apply additional coats of sealant. Luckily, more absorbent stone also means less waiting time between coats of sealant.

It’s a good idea to wait at least 15 minutes before applying a second coat of sealant. This will allow the first layer to be fully absorbed by the stone. If you’re using a solvent-based sealant, the stone should look dry before you apply the next layer of sealant. With water-based sealants, the stone may still have a wet look.

Some sealants, like ones designed for granite, require waiting at least 30 minutes between applying coats. If the manufacturer’s instructions specify a different time period, follow their recommendations.

Guidelines for Properly Sealing Granite Countertops

When sealing your granite countertops, there are various products you don’t want to use. Avoid sealing granite tops with:

• Citrus ingredients: Acidic juices, such as lemon and orange, can strip the sealant from your countertops and cause discoloration and dull the surface. Read the ingredients on the cleaner to make sure it does not contain citrus oils.
• Linseed oil: Linseed oil is a popular, nontoxic, food-safe sealer. However, it’s not the best option for granite countertops, especially white ones, because it can turn the surface yellow.
• Silicone-based sealers: Silicone-based sealers have been the go-to material for many years, but they’re not as effective as other types. When you use a silicone-based sealer, you’ll have to reseal your countertops more often.
• Siloxane sealers: Siloxane sealers are slightly more effective than silicone-based ones, but they require frequent application and are typically tougher on the surface.

Several DIY granite countertop sealer recipes are available online. Avoid these recipes because they use citrus solvents, linseed oil, or both!

What to Use for Sealing Granite Countertops

Look for a sealant designed especially for granite surfaces. These differ from those designed for natural stone. Because granite is so dense, the solvents and resins used in granite sealers need to be very lightweight.

The best sealers for granite are:

• Impregnators or penetrating sealers: These contain a resin dissolved in water or a petroleum-based solvent. Because granite is porous, the countertop absorbs these materials and fills in the gaps to prevent staining, giving you more time to clean up spills and residue.
• Sealers with fluorocarbon aliphatic resins: These sealants are water-based, nontoxic, and durable. They don’t evaporate or deteriorate and are excellent at repelling oil from your countertops.
• Food-safe sealers: These are best if you store fruits and other food products on your countertops, as they contain ingredients that provide peace of mind that your food is free of harmful chemicals.

Guidelines for Sealing Marble Countertops

For marble countertops, there are also some ingredients you’ll need to avoid. Don’t use the following types of sealers:

• Citrus solvents or ingredients: Marble is a porous, calcium-based rock that reacts with acid. When acidic items, like lemons, vinegar, or even strawberries, come into contact with the marble, the acid and calcium interact to create these dull spots. That’s why it’s vital to avoid sealers with acidic ingredients like citrus solvent. These will actually damage your marble counters.
• Surface sealants: You should seal your marble countertops with impregnators and penetrating sealers that penetrate the surface. Otherwise, they won’t be properly protected.
• Linseed oil: Linseed oil is often touted as a nontoxic, nonVOC sealant, but it is not suitable for marble. The oil can turn your white marble yellow, so it’s best to use a different product to maintain your countertops’ luxurious appearance.
• Tung oil: Avoid tung oil as well. It will yellow over time, making your once white marble counters look old and dirty. Look for a nontoxic marble sealer instead.

Many people see etchings on marble and believe the stone needs to be sealed, but not all marble needs to be sealed. Test your marble countertop with water or mineral oil to determine whether it needs additional protection. Keep in mind that sealing marble won’t help to prevent etchings. Etching is a change in the chemical composition of the marble, which occurs when an acid comes into contact with calcium.

What to Use for Sealing a Marble Countertop

The best marble sealer is nontoxic and acid-resistant. The best sealants are designed especially for the stone you’re sealing. Look for a penetrating sealer for marble, which is sometimes called marble and granite sealants. Avoid sealants that specify use for bathroom countertops and tiles unless they specifically say food-safe.

Both water-based and solvent-based sealants will work on a marble surface, but the best choice depends on what you want to accomplish. Solvent-based sealants are better at repelling water, while water-based sealants are better at repelling oil. Consider what types of activities you usually use the surface for, and choose the sealant accordingly. The best marble sealants include:

• Impregnators: Impregnators go under the surface of your marble countertops to prevent liquids from entering the pores. Keep in mind that this type of sealant doesn’t protect the surfaces against etching.
• Acid-resistant sealers: Since acids can damage the surfaces of your countertops, try to find a sealer that protects them against acidic substances.
• Acid-resistant coating: There are coatings on the market that protect your surfaces from acidic materials. Most have a reputation for cracking, chipping, peeling, or discoloring stone countertops.

Honed marble typically absorbs more sealant than polished marble. If possible, find a sealer that is also designed for your stone’s finish.

How Often Should You Reseal Your Countertops?

We recommend that you decide whether to seal your countertops based on what your countertops need, rather than on an arbitrary calendar. Some counters don’t need any sealant, and this is normal. If you’d like natural stone counters without needing to seal them regularly, consider having a professional apply a sealant like Dry-Treat Stain Proof.

If you’re not sure whether your stone countertops need sealing, there are a couple of simple tests to help you figure it out.

Mineral Oil Test

Use a solvent test to figure out if you need to seal your natural stone countertops. Follow these tips for using a petroleum-based liquid or solvent to determine your countertops’ seal:

• Put a few drops of mineral oil in an out-of-the-way spot on your counter.
• Wait 10 minutes, then wipe up the mineral oil with a dry cloth.
• If a dark stain shows when you wipe up the mineral oil, it’s time to reseal your countertops.

Don’t worry if the mineral oil leaves a mark. Even if your counters need to be sealed, the dark spot from the mineral oil will evaporate in about 30 minutes.

Water Drop Test

Another method to test whether you need to seal your natural stone countertops is to use water. Follow these steps to perform the water test on your stone surfaces:

• Find an unnoticeable area on your countertop.
• Pour a tablespoon of water on the treated surface for 20 minutes.
• Set a timer and track how long it takes for the countertop to absorb the water.
• Check to see whether the stone darkens and absorbs water. If it does and leaves a dark spot, the stone needs to be resealed.

Since it takes just a few minutes and no special materials to complete a water test, this is an easy test to do every few months. You can also use the water test to determine the best resealing schedule. To find out how often to seal your countertops, keep the following absorption rates in mind:

• Instant: If water absorbs instantly, seal your countertops once a year and wipe off spills immediately. You may also need to apply a few layers of sealant to protect your surfaces fully.
• Four to five minutes: If it takes a few minutes for the surfaces to absorb water, seal your countertops about every three to five years. You’ll need to apply a few layers of sealant.
• 10 minutes: If the water fully absorbs into your countertop after 10 minutes, you only need to apply one layer of sealer every few years.
• 30 minutes: If there’s little or no water absorption from your countertops after thirty minutes, you don’t need to apply a sealer at all.

How to Maintain Your Sealed Surfaces

How long a sealer lasts depends on the product used, the type of stone, and how heavily the surface is used. Proper upkeep can extend their performance and beauty. This starts by choosing the right cleaning agents. While most household cleaners are safe to use on granite, a pH-neutral cleaner designed for natural stone ensures you’re not weakening the sealer or damaging the surface. Strong acidic cleaners can erode the protective layer, and abrasive powders and rough pads can scratch or dull the finish. Sticking to gentle, stone-safe cleaners can extend the life of the sealant and stone.

The way you use your countertops also matters. Minor adjustments and mindfulness go a long way toward preserving the finish. Be sure to wipe spills soon after they happen to prevent them from lingering long enough to cause marks. You should also use cutting boards to protect your knives and minimize direct contact with the stone.

Preserve the Beauty and Performance of Your Marble or Granite Countertops

When you invest in granite or marble, you want the surface to keep its beauty for years to come. Lesher Natural Stone, Quartz, & Tile has over 20 years of experience helping homeowners find, install, and maintain their custom stone surfaces, from kitchen countertops and bathroom vanities to fireplaces and sinks. We design and fabricate custom solutions that elevate your space and partner with trusted installers who bring our designs into your home.

Plus, all natural stone products leave our shop sealed with a Dry-Treat product called Stain-Repella — a penetrating, invisible, and breathable water-based sealer. For an additional charge, we offer a 15-year sealer by Dry-Treat called Stain-Proof or the 25-year sealer called Stain-Proof Plus.

Give us a call at 717-964-4032 or fill out our contact form to get started. You can also visit our 20,000-square-foot showroom in Middletown to explore granite, marble, quartz, and tile options that match your style.