Granite, Marble, and Onyx: A Guide for Sealing Countertops

Granite, Marble, And Onyx: A Guide For Sealing Countertops

One of the best (and easiest) ways to add value to your home is keeping your countertops looking like new. This is fairly easy if your countertops were already sealed by the manufacturer. If your countertops aren’t already sealed, you can seal them yourself. Sealing countertops prevents damage to the stone and makes cleaning up spills easier. It also prevents stains. In most cases, countertops, especially granite ones, do not need to be sealed. However, if your counter does need sealing, it likely only needs a touch-up about once a year. Keep reading to learn more about sealing countertops, different treatments for different materials, and how to tell when your countertop needs a refresher.

Testing Your Countertops

One of the allures of natural stone countertops is that each one is unique. That uniqueness comes not only in the pattern of the stone but also the porousness of the stone. What this means is no two slabs of granite or marble have the same level of absorbency. Even if the two pieces of stone come from the same quarry, there is a chance they will have different levels of porousness. The easy way to tell if your countertop needs a sealant is to use a solvent test. This means you test to see whether a solvent or petroleum-based liquid will enter the stone and stain it. To test your countertop, apply mineral oil to a small area on your countertop and leave it for about 10 minutes. When you wipe up the mineral oil, check to see if there’s any darkening in the stone. If there isn’t darkening, it’s an indication your countertop won’t be stained by anything else. If there is darkening, you’ll want to seal your countertop. Also, don’t worry about the darkening from the mineral oil as it will evaporate. This test works for any natural stone surface. There is one caveat with marble which is an impregnating sealer will not protect the stone from etchings as a result of chemical reactions.

Sealers 101

Before we discuss selecting a sealer, we need to explain what a stone sealer does. When we think of sealers, most of us think about a protective layer that sits over a material. This type of sealer is most similar to the veneer layer applied to wood furniture or hardwood floors. Natural stone sealers do not sit on the surface of the stone. Instead, they sit below the surface, or impregnate, the stone and protect the pores of the stone from below. Knowing how stone sealers work relates back to the absorbency test. If a piece of stone doesn’t absorb the mineral oil, it’s not going to absorb a sealer. There are many sealers on the market, all with varying efficacy. You’ll see those with silicone resins, siloxane resins, and fluorocarbon aliphatic resins. Silicone resins are the least effective sealers. They wear off quickly and hardly any stone manufacturer uses them. Siloxane resins are tougher than silicone resins and last longer. They typically wear off every 5 years or so. They’re also a bit more expensive. Fluorocarbon aliphatic resins are the most expensive sealers and also the most durable and long-lasting. Most professional installers agree they are the best option available for homeowners with stone countertops.

Materials to Seal Your Countertop

Once you’ve tested your countertops and determined if you need to seal them or not, you’ll need to collect the other necessary tools to do so.

Apart from your chosen sealer – again, we recommend fluorocarbon aliphatic resins – you’ll need to get your hands on the following items:

  • Untreated microfiber cloths
  • Clean spray bottle
  • Liquid dish detergent
  • Rubbing alcohol
  • Rubber gloves
  • Soft rags

Once you have everything for sealing countertops, you can get started.

A Countertop Sealing Guide

The whole process of sealing countertops can take between 48 to 72 hours. You’ll need to avoid using the surface during the time you’re cleaning and sealing it.

Step 1

First, you need to thoroughly clean the countertop. Take everything off the surface and wipe it down with a microfiber cloth to collect any dust. Next, mix one teaspoon of dish detergent with two tablespoons of rubbing alcohol in the spray bottle and fill it up with cool water. Generously spray the countertop with the mixture and wipe the counter off with a microfiber cloth. Wait 24 hours before moving to the next step.

Step 2

After 24 hours, you can move to the sealing process. Before starting, thoroughly read the instructions on the bottle of sealer. Also, open a few windows or doors to allow a cross-flow of air to move through the room in which you’re sealing.

Step 3

Before applying the sealant to your entire counter, you should test it in one spot. Pick an area no one can see like under a kitchen appliance. Put on your rubber gloves and apply the sealer to the test area according to the manufacturer’s instructions. Wait for 15-20 minutes to allow the sealer to absorb. If the sealer hasn’t discolored the countertop after the allotted time, proceed to the next step. If there’s some discoloration, wipe up the remaining sealer, take a picture of the countertop, and ask someone at your local hardware store to recommend a different sealer. You can find stain removal tips here, too.

Step 4

If your sealer looked great after your test application, apply it to the rest of the countertop. Working in patches, apply the sealer with sweeping circular motions to ensure even coverage. Allow the sealer to absorb for the time noted on the bottle. Once that time has passed, wipe up any remaining sealer with a soft cloth using the same circular motions you used to apply it. Depending on the instructions, you’ll allow your counter to cure for two to 48 hours. Most countertop professionals recommend you wait the full 48 hours before getting the counter wet again.

Step 5

Once the cure period is over, you can put everything back in its place and enjoy your newly sealed countertops! Keeping your counters clean will also help lengthen the lifespan of the sealer.

The Truth About Sealing Countertops

The truth is many manufacturers of countertop sealers instill fear into homeowners about their countertops. Doing this encourages homeowners to over-seal their countertops which is bad for them. In reality, you only need to seal your countertops once a year or so if you use siloxane resins and even less if you use fluorocarbon aliphatic resins. Sealing counters also isn’t difficult like some would have you believe. It’s only a time-consuming process, but it’s worth it to protect counters that need it. If you have more questions about sealing countertops, get in touch with us today.

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