How often should you seal granite or marble countertops?

Short answer

Reseal the stone countertops every 1 to 3 years for granite, every 6 to 12 months for marble. Natural stone is porous, and a sealer fills the pores so spills sit on the surface long enough to wipe up. Marble is softer and more porous than granite, so it needs sealing far more often. Engineered quartz isn't natural stone and doesn't need sealing at all. The job takes 30 to 60 minutes and the sealer costs $15 to $40.

Why it matters

A stone countertop looks solid, but under a microscope it's full of tiny channels. Oil, wine, coffee and the juice from a lemon all find their way in. Oil leaves a dark patch around the stove that doesn't wipe away. Acids etch marble on contact, leaving a dull spot in the polish. A sealer doesn't make the stone bulletproof, but it buys you time: a spill beads up and sits there for minutes instead of soaking in on contact, and minutes is usually all you need.

The sealer wears away with cleaning, especially with the wrong cleaners, and once it's gone the stone goes back to absorbing whatever lands on it. A stain that's soaked into stone is hard to get out, and etching in marble takes professional polishing to fix. Resealing on schedule is the difference between a countertop that looks new for decades and one with a permanent ring where the olive oil bottle sat.

When to do it more often

The stone decides the schedule. Granite is dense and holds a seal for 1 to 3 years. Marble, limestone and travertine are soft and open-grained and need resealing every 6 to 12 months. Quartz, which is crushed stone bound in resin, doesn't absorb anything and is skipped.

Between those, the countertop around the stove and the sink sees the most oil and water, so test those spots first each time. If water darkens the stone there but still beads on the island, seal the working area and leave the rest for the next round.

What you need

• Clean, dry cloths for applying the sealer and buffing off the excess
• A stone sealer, a penetrating one made for natural stone

Steps at a glance

1. Clear the countertop and clean it with a stone-safe cleaner, then let it dry fully.
2. Put a few drops of water on the stone in several spots and watch: if any darkens within minutes, that area needs sealing.
3. Wipe sealer onto the stone with a cloth in a thin, even coat, working a section at a time.
4. Let it soak in for the time on the label, then buff off every trace of excess with a dry cloth before it dries on the surface.
5. Apply a second coat if the first soaked in quickly, which marble often does.
6. Keep the counter dry and clear for the cure time on the label.

You're done when a drop of water beads on every part of the counter and sits there without darkening the stone.

Signs it's overdue

• A drop of water soaks in and darkens the stone within a few minutes.
• Dark patches or stains around the sink and the stove, where oil and water land most.

DIY or pro

This is an easy job, closer to polishing furniture than to anything in the toolbox. The skill is in buffing off the excess before it dries, because sealer left on the surface turns into a hazy film that's harder to remove than the stain it was meant to prevent. Work a small section at a time and keep a dry cloth in the other hand.

A stone company charges $100 to $300 to seal a kitchen's counters, and some include it with a polishing service. That's worth it for marble that's already etched or stained, because sealing locks the damage in and polishing has to come first. For granite in good shape, the bottle and an hour are all it takes.

Safety

• Chemicals: stone sealers are solvent-based and the fumes are strong in a closed kitchen. Open the windows, turn on the range hood, wear gloves, and keep the sealer away from food, the stove's pilot light and any open flame until it has cured.

FAQ

How do I know if my granite needs sealing?

Drop water on it. If it beads, the seal is good. If it soaks in and darkens the stone within a few minutes, reseal.

Does quartz countertop need to be sealed?

No. Quartz is bound in resin and doesn't absorb liquids. Sealer has nothing to soak into and leaves a film on top.

Why does marble need sealing more often than granite?

Marble is softer and more porous, so it takes in spills faster and wears through its sealer sooner. It also etches from acids, which sealer slows but doesn't stop.

Can I use any cleaner on sealed stone?

No. Vinegar, lemon and most bathroom cleaners are acidic and strip the sealer, and they etch marble outright. Use a cleaner made for stone or plain soap and water.