How to Remove Stains from Bluestone: Mold, Rust, & More

Bluestone is a popular, durable choice for pool decks, patios, and walkways. It looks incredible when installed, but like any natural stone, it isn’t immune to messes. Stains happen, and when they do, your beautiful landscape feature can start looking dingy fast.

Wondering how to remove stains from bluestone without ruining the surface? We have you covered. We will break down four primary cleaning methods, plus specific tricks for tackling rust, mildew, and hard water deposits.

Here is the ultimate guide to keeping your bluestone looking brand new.

Does Bluestone Stain Easily?

Bluestone is naturally porous. While it is denser and more stain-resistant than limestone or travertine, it is still susceptible to discoloration. If liquids sit on the surface too long, they will seep in.

You must seal bluestone pavers to keep them resistant to oil, water, and organic grime. Common culprits for stains include damp leaves (tannins), rusting patio furniture, grease from grills, and mildew.

To maintain that protection, aim to reseal your bluestone every six to 12 months.

How To Remove Stains From Bluestone

It is time to get cleaning. We always recommend starting with the gentlest method and working your way up to harsh chemicals only if absolutely necessary. Here are the four most effective ways to clean up your stone.

With Soap and Water

For most dirt, food spills, and fresh grime, simple dish soap is your best friend. It cuts through grease without damaging the stone’s finish.

1. Clear the deck: Sweep the area thoroughly to remove loose dirt, leaves, and debris.
2. Mix the solution: Combine ½ cup of dish soap with a gallon of water in a bucket. Stir it up until suds form.
3. Scrub the stone: Dip a stiff-bristle scrubbing brush (avoid wire brushes) into the mixture. Scrub the stain in a circular motion. You can apply a fair amount of pressure on bluestone, so put some muscle into it.
4. Rinse away: Once the stain lifts, rinse the area with fresh water from a hose or a clean bucket.

With Vinegar

Vinegar is acidic, so it works well on mineral deposits and efflorescence. However, proceed with caution. Acid can dull sealed surfaces, so dilute it properly.

1. Sweep up: Remove surface dirt and debris first.
2. Dilute the vinegar: Mix a solution of 50 percent distilled white vinegar and 50 percent water in a bucket.
3. Apply and scrub: Dip your brush into the mixture and scrub the stained area. Do not let the vinegar sit on the stone for long periods.
4. Rinse thoroughly: Flush the area with plenty of plain water to neutralize the acid and wash away the residue.

With Ammonia

If you are dealing with organic stains like moss, algae, or bird droppings, ammonia is a powerful cleaner. It breaks down biological matter effectively.

1. Prep the area: Sweep away loose organic matter and dirt.
2. Mix the cleaner: Add two teaspoons of ammonia to one liter of water. You can scale this up for larger areas.
3. Scrub and wait: Apply the solution to the stain with a brush. Let it sit for about five minutes to break down the grime, then scrub vigorously.
4. Rinse: Wash the area clean with a hose.
5. For stubborn spots: If the stain remains, mix two drops of ammonia with ½ cup of 12 percent hydrogen peroxide. Apply, wait five minutes, scrub, and rinse.

With Muriatic Acid

Muriatic acid is a harsh chemical. It should be your last resort. It works by etching a micro-layer of the stone away, taking the stain with it. If used incorrectly, it can ruin your pavers or burn your skin.

We highly recommend hiring a professional for this step. If you choose to DIY, follow these instructions strictly.

1. Safety first: Wear heavy rubber gloves, safety goggles, and a respirator mask. Cover nearby plants with plastic tarps.
2. Dilute the acid: Fill a plastic bucket with 10 parts water. Slowly add one part muriatic acid. Always add acid to water, never the other way around, to prevent dangerous splashing/reaction.
3. Apply carefully: Use a long-handled masonry brush to apply the mixture to the stain.
4. Let it work: Allow it to sit for a maximum of two to three minutes. Do not let it dry.
5. Scrub and rinse: Scrub the area and immediately rinse with massive amounts of water.
6. Neutralize: Sprinkle baking soda over the area to neutralize any remaining acid, then rinse again.

Disposing of leftover muriatic acid requires care. Do not pour it down the drain or into the soil.

1. Neutralize the waste: In a large plastic container, place three to four cups of lime or baking soda.
2. Add acid slowly: Slowly pour the leftover acid mix into the neutralizer while stirring with an old stick.
3. Check reaction: Once the fizzing stops, the acid is neutralized.
4. Dispose: You can now safely pour the mixture down a utility sink, flushing with plenty of water.

How To Remove Water Stains From Bluestone

Hard water or mineral runoff can leave chalky white or rusty deposits on your stone. Regular cleaning with hard water can actually make this worse.

Here is a method to dissolve those minerals:

1. Clean surface: Sweep the area clear.
2. Make a paste: Mix baking soda and a small amount of water to create a thick paste.
3. Apply: Spread the paste over the water stains and let it dry for a few hours.
4. Scrub with vinegar: Pour a little white vinegar onto the dried paste. It will fizz. Scrub the area with a brush while it reacts.
5. Rinse with filtered water: Rinse the area. If possible, use distilled water or a hose filter to prevent adding new mineral deposits back onto the stone.

Removing Rust Stains From Bluestone

Metal patio furniture and fire pits are notorious for leaving orange rust rings. You need a specialized chemical to draw the iron oxide out of the stone pores. Use a poultice or cleaner like Singerman Laboratories Rust Remover.

1. Read the label: Follow the specific dilution ratios on your chosen rust remover. Wear gloves.
2. Apply the cleaner: Spread the mixture generously over the rust stain using a plastic spatula or spoon.
3. Wait: Let the cleaner sit for the time recommended by the manufacturer.
4. Rinse well: Blast the area with a garden hose or pressure washer to remove all chemical residue.

How To Remove Mildew From Bluestone

Shaded areas often develop black or green mold and mildew. Hydrogen peroxide is an excellent solution for this because it kills the spores without the harsh fumes of chlorine bleach.

1. Sweep: Clear leaves and dirt from the spot.
2. Mix solution: Combine ½ cup of 3% hydrogen peroxide with one gallon of water.
3. Saturate: Pour the mixture over the mildew and let it sit for roughly 10 minutes.
4. Scrub: Use a stiff bristle brush to agitate the stain.
5. Rinse and dry: Rinse well. Use a wet vacuum to pull up excess water, which helps prevent immediate regrowth.

Tips For Bluestone Maintenance

Prevention is always easier than deep cleaning. Follow these maintenance tips to keep your bluestone looking sharp year-round.

• Annual pressure washing: Give your patio a light power wash once a year to remove embedded dirt. Keep the pressure low to protect the stone texture.
• Routine sweeping: Dirt and wet leaves left on the surface can cause staining. Sweep your patio weekly.
• Use neutral cleaners: For regular maintenance, stick to pH-neutral stone cleaners or mild dish soap. Avoid using vinegar or lemon juice for daily cleaning.
• Seal regularly: A high-quality sealer prevents absorption. Apply a new coat every year or two. Dominator Stone+ Gloss Sealer is a reliable option.
• Clean spills instantly: Grease from a burger or red wine will stain quickly. Blot spills immediately rather than wiping them, which spreads the mess.
• Elevate pots: Place planters on “pot feet” or stands. Moisture trapped under pots creates stubborn dark rings and encourages mildew.

FAQs

How Do You Get Oil Stains Out of Bluestone?

For oil or grease, you need a poultice. Mix baking soda with acetone (or water) to form a thick paste like peanut butter. Spread it over the oil stain, cover it with plastic wrap, and tape down the edges. Let it sit for 24 to 48 hours. The paste will pull the oil out of the stone as it dries. Remove the plastic, scrape off the dried paste, and rinse.

Does Vinegar Damage Natural Stone?

Vinegar is acidic and can etch or dull calcium-based stones like marble and limestone. Bluestone (sandstone) is more resistant to acid, but frequent use of vinegar can still degrade the sealer or finish over time. Use it only for tough mineral stains and always rinse thoroughly.

Does Bluestone Darken Over Time?

Yes, unsealed bluestone will naturally darken as it is exposed to the elements and absorbs moisture. UV rays can also fade the blue-grey color into a lighter grey or brown over many years. Regular sealing helps maintain the original color depth.

Can I Use Bleach on Bluestone?

You can use diluted bleach to treat organic stains like mold, but it is harsh. A safer alternative is mixing water and ammonia (never mix ammonia with bleach) or using hydrogen peroxide. If you must use bleach, dilute it heavily and rinse it away quickly to prevent discoloring the stone.

Blasting Away Bluestone Stains

Removing stains from bluestone doesn’t have to be a headache. Whether you are dealing with BBQ grease, rust spots, or just general grime, there is a solution.

Start with simple soap and water. If that doesn’t work, move on to vinegar or ammonia for specific stain types. Save the heavy-duty acids for the worst-case scenarios and always prioritize safety gear. With a little scrubbing and regular sealing, your bluestone will stay beautiful for decades.