How to Clean Slate Tiles on a Fireplace

• Sweep your slate and wipe it down with a few drops of mild dish detergent mixed into warm water each week to keep it shining.
• Spritz a mixture of equal parts of hydrogen peroxide and warm water onto stains, let it soak for 10 minutes, then wipe it away with a damp rag to deep clean slate.
• Dampen a soft cloth with teak oil, slate oil, or WD-40, and buff it onto the slate in a thin layer with circular motions to polish the surface.

Weekly Maintenance

Sweep the slate to remove any loose dirt. With a dry broom or dust mop, remove any dust, ash flakes, or other debris items from the surface of the slate hearth before you proceed to clean it with the dish soap mixture. Move the broom in one direction, pushing any debris off the slate. Make sure you remove any dust or dirt in the grout trenches between the slabs of slate as well. Aim to sweep the slate once a day, if possible, or at least once a week, to keep the stone free of dust or other buildup.

Mix 2-3 drops of mild dish detergent into a bucket of warm water. Slate needs a gentle cleaning solution to avoid damage. Cleaning Specialist Jon Gholian recommends a mixture of mild detergent or dish soap plus water. Fill a bucket with 2–3 US gal (7,600–11,400 mL) of warm water, then add just 2-3 drops of a mild dish detergent, and mix it well. Opt for an unscented, all-natural detergent for best results, or use an all-purpose surface cleaner or specialized slate cleaning solution. Never use products containing lemon, vinegar, or other acidic ingredients, as these can damage the porous slate.

Scrub the slate with a cloth or mop soaked in the soapy water mix. Dip your cloth or mop into the mixture, then ring it out slightly to get rid of excess moisture—make sure it’s damp, but not dripping. Then, scrub the slate using circular motions to clean it. Rinse the mop in the cleaning solution often, and refresh the solution any time the mop starts to streak. Use gentle but firm pressure while mopping. If a gentle once-over isn’t enough to clean off any dirt and grime on your hearth, it may be time for a deep-clean instead. Pay special attention to the corners and grouting, where grime tends to build up unnoticed.

Spritz and wipe the slate with clean water to rinse it. Spray small amounts of water onto the slate with a spray bottle, or dampen a new, clean cloth with clean water. Then, wipe down the slate with smooth, circular motions to remove any excess cleaning solution.

Use a clean towel to dry any excess moisture off of the slate. Use a soft, dry towel to wipe the slate again, also in smooth circular motions. This time, you’re drying it off so that there’s no lingering moisture that may stain the slate. After, allow the hearth to air dry overnight if you intend to polish it after you clean it.

Wipe down the slate with teak oil to polish the stone. Dampen a fresh cloth with teak oil or specialized slate oil, then buff it into the clean slate with circular motions, until the slate is just coated in a thin sheen. After, use a second clean cloth to remove any excess oil from the surface. Make sure the oil isn’t pooling, as excess oil may be absorbed by the slate, causing wear or damage. A light spritz of WD-40 buffed into the slate with a soft cloth also makes for great polish. Oil also helps hide scratches on your hearth, making it easier to seal.

Deep Cleaning & Removing Stains

Soak up spills as soon as possible. Slate is a porous stone, and so it’s prone to sucking up any fluids that spill onto it. The best way to clean spills is to soak them up with a clean rag or towel ASAP, before they have a chance to settle, then treat them with a quick clean afterward.

Sweep and wipe down the slate. Remove any superficial grime by sweeping off the slate with a broom or dry dust mop. Then, with a just-damp rag, wipe it down with smooth, circular motions to lift any slightly more stubborn debris.

Mix a solution of equal parts hydrogen peroxide and warm water. Pour a 1:1 ratio of hydrogen peroxide and warm water into a spray bottle and give it a shake to mix it up. Alternatively, mix these ingredients into a bucket if you don’t have a spray bottle. Or, use a mixture of equal parts of baking soda and hydrogen peroxide to provide stronger cleaning power, or use 1 part of rubbing alcohol with 8 parts water as an alternative. You might also use a specialized slate or stone cleaning solution. These come in many forms and formulas, so follow the manufacturer’s instructions. Never use products containing vinegar, lemon, or other acidic ingredients, as these can damage the porous slate.

Spray the mixture onto the stain and let it sit for 10 minutes. Apply a thin layer of the water and peroxide mixture directly to the surface of the stain. Let the mixture sit for 5-10 minutes, to let it soak and loosen the stain, before proceeding. Avoid spraying this mixture near any colored grout, since the bleach in the mixture can discolor your grout.

Scrub the stain with a soft scrub pad or brush. Scrub in a circular motion and with firm but gentle pressure in order to clean the slate without damaging it. If you used baking soda and hydrogen peroxide instead of the water mixture, use a moist cloth to scrub the slate. Avoid steel wool or particularly firm or abrasive tools, as these can scratch the slate.

Use a Trisodium Phosphate (TSP) mix on tougher stains. Mix 1 tsp (4.9 mL) of water and 2 tsp (12 g) of TSP to make a paste (or follow the instructions provided by the manufacturer). Spread the paste onto a soft sponge and use that sponge to gently scrub the slate. Finally, soak a separate clean sponge in water and use it to remove any residue from the slate surface. This method is particularly effective on smoke or soot stains.

Wipe down the spot with a clean rag and allow it to air dry overnight. Dampen a rag and wipe down the spot to remove any excess cleaner. Then, for best results, allow the slate to dry overnight before putting anything on it or using the fireplace.