# How to Clean Slate Floors: A Commercial Guide to Routine, Cleaners, Sealing and Machines

> How to clean commercial slate floors: sweep, damp-mop with a pH-neutral stone cleaner, rinse residue, skip acids and steam, check the seal, and match the machine to the finish.

- **URL:** https://janitori.com/blogs/equipment-guides/how-to-clean-slate-floors

**In this guide**
- [Is your slate cleft or honed?](#finish)
- [How do you clean slate floors step by step?](#steps)
- [Which cleaner is safe for slate?](#cleaner)
- [What damages slate floors?](#avoid)
- [How do you know if slate needs sealing?](#seal)
- [Which machines work on slate floors?](#machines)
- [Are slate floors slippery when wet?](#traction)
- [FAQ](#faq)

To clean a slate floor, sweep or vacuum first, damp-mop with a pH-neutral stone cleaner, rinse away the residue, and dry the surface. Acids, abrasive tools and excess water are what damage slate.

This guide is for facility and custodial teams caring for slate in lobbies, entryways, restaurants, hotels and retail. It covers the routine, the cleaner, the seal, and the machines that fit each floor.

 **Key takeaways**
- Use a pH-neutral stone cleaner, never acids. MSI says vinegar, lemon juice and bleach attack the mineral makeup of slate, creating microscopic etching that dulls the surface over time.
- Keep the mop damp, not soaking. The Tile Shop warns that excessive moisture can seep into slate and cause problems even when it is properly sealed, so wring out the mop and mop in sections.
- Rinse and dry after cleaning. The Tile Shop says a clean-water rinse prevents a film or buildup from forming on the slate after it dries.
- Match tools to the finish. MSI says cleft slate traps dirt in its ridges while honed slate shows water spots, and both are scratched by wire brushes and scouring pads.

## Is Your Slate Cleft or Honed?

Know the finish before you clean, because the two respond differently to dirt, moisture and tools. MSI describes two main finishes, cleft and honed.
- **Cleft slate** has the rough, layered texture of stone as it comes from the quarry. MSI says it hides scratches and has natural slip resistance, but its ridges and grooves trap dirt and crumbs.
- **Honed slate** is ground smooth to a matte or low-sheen finish. MSI says it is easier to wipe clean but shows water spots and surface dirt more readily.

Slate is a layered metamorphic stone. MSI notes those layers can be penetrated by harsh chemicals, acidic solutions or abrasive tools, which can cause flaking or discoloring.

## How Do You Clean Slate Floors Step by Step?

Dry-clean, damp-mop in sections, rinse away residue, and dry. The Tile Shop recommends cleaning slate at least once a week, and more often in high-traffic areas.
- **Close the area.** Put out wet-floor signs and keep foot traffic off the section being cleaned.
- **Sweep or vacuum.** Use a soft-bristled broom or a vacuum with a soft brush attachment, and pay attention to grout lines where dirt collects. MSI says dirt, sand and grit slowly scratch slate, and recommends the hard-floor setting for honed slate.
- **Test first.** The Tile Shop says to test any cleaning solution on an inconspicuous area to check for discoloration or etching.
- **Mix the cleaner at the label rate.** Use a stone-safe, pH-neutral product and follow the instructions on its label.
- **Mop damp, in sections.** Wring the mop out so it is damp, not soaking, and rinse the mop often so you do not spread dirt around.
- **Rinse.** The Tile Shop says to rinse away cleaner residue with clean water on a separate mop so no film builds up.
- **Check the recovery tank.** If you use a wet vacuum or scrubber, look for foam on the first fill, because foam pulled into a vacuum motor damages it.
- **Dry.** Let the floor air dry or wipe it with a clean microfiber cloth or mop head. MSI says this last pass prevents mineral deposits drying on the surface and is especially useful on dark slate where water spots show.

For grout joints on cleft slate, MSI says to scrub gently with soft bristles, never a metal scrubber, apply the pH-neutral cleaner, let it sit for two to three minutes, then scrub and rinse thoroughly.

 **Run it with JANITORI chemistry**

 [Floor Cleaner No.61](/products/floor-cleaner-janitori-no-61)

The routine damp-mop product. It is pH-neutral, low-residue and low-foam at label dilution, and is labeled for mop or cleaning-system use on concrete, stone, ceramic, wood, laminate, marble, granite and terracotta. Stone is named on the label, but slate is not, so test a hidden area first and confirm with your slate supplier. The label says no rinse under normal conditions, but a clean-water rinse is what slate guidance recommends, so rinse or recover the solution on slate.

## Which Cleaner Is Safe for Slate?

A pH-neutral cleaner made for natural stone is the safe routine choice. Both The Tile Shop and MSI say to avoid acidic cleaners on slate.

 | Product type | Use on slate? | Why

 | pH-neutral stone cleaner | Yes, first choice | MSI recommends damp microfiber mopping with a pH-neutral stone cleaner

 | Vinegar, lemon juice and acidic cleaners | No | The Tile Shop and MSI both say acids damage slate; MSI says they etch the surface and break down the seal

 | Bleach | No | MSI says never to use bleach on natural slate

 | "Natural" or citrus all-purpose sprays | Test first, or avoid | MSI says they may contain citrus oils or other acidic ingredients

 | Abrasive cleaners and tools | No | The Tile Shop says abrasive tools can damage slate

Where the slate supplier or installer names a maintenance product, follow that.

## What Damages Slate Floors?

Acids, abrasive tools, steam and standing water cause most slate problems. Each etches the surface, scratches it, breaks down the seal or pushes water into the stone.
- **Acidic cleaners.** MSI says acids attack the mineral makeup of slate, and repeated use can cause permanent damage.
- **Wire brushes and scouring pads.** MSI says wool, scouring pads and stiff wire brushes scratch both cleft and honed slate.
- **Steam.** MSI does not recommend steam mops on natural slate, because heat can damage the sealer bond and forced moisture can seep into the stone's layers.
- **Too much water.** The Tile Shop says excessive moisture can seep into slate and cause issues, even when it is sealed.
- **Skipping the dry pass.** MSI says dirt, sand and grit slowly scratch slate surfaces over time.

## How Do You Know if Slate Needs Sealing?

Run a water drop test. MSI says to place a few drops of water on the tile and wait 30 seconds: if the water beads up and runs off the seal is healthy, and if it darkens the stone and soaks in, it is time to reseal.

MSI says natural slate is porous and recommends resealing every one to three years for most residential installations. Commercial traffic is a different load, so ask the installer or sealer maker for a schedule that fits your floor, and clean the floor and let it dry fully before any sealer goes on.

If you see a white haze on slate, MSI says it is usually either excess sealer that was not fully buffed off or mineral deposits from hard water. For mineral deposits it recommends a non-acidic, stone-safe descaler and warns never to use vinegar.

## Which Machines Work on Slate Floors?

An auto scrubber suits large slate floors, a hand-held scrubber suits restrooms and tight corners, and a floor machine suits mid-size rooms. Because moisture is the risk, a machine that recovers its solution in the same pass can help keep the floor from staying wet.

 | Floor size or task | Machine | Notes

 | Restrooms, tight corners, spot work | [Dapper Supply DP-HFS1240](/products/dapper-supply-hand-held-floor-scrubber-machine-17-brush-17-5-squeegee-1-2-gal-tank-dp-hfs1240) | 17 in brush and 17.5 in squeegee, so it scrubs and recovers in confined spaces

 | Small retail, hotel lobbies and entryways | [Dapper Supply DP-WPFS1204](/products/dapper-supply-mini-automatic-floor-scrubber-machine-15-brush-17-squeegee-dp-wpfs1204) | 15 in brush and 17 in squeegee

 | Larger slate floors | [Dapper Supply DP-WBFS1218](/products/dapper-supply-walk-behind-floor-scrubber-machine-20-brush-31-5-squeegee-dp-wbfs1218) | 20 in brush and 31.5 in squeegee. [How to size a commercial floor scrubber](/blogs/equipment-guides/best-commercial-floor-scrubber)

 | Mid-size rooms | [Floor machine](/collections/floor-machines) such as the [Mercury Cleanmaster TS-19](/products/mercury-cleanmaster-dual-speed-floor-machine-19-apron-175-300-rpm-1-5-hp-d-c-rectified-model-ts-19) | 19 in apron, dual-speed 175/300 RPM. Pair with a wet vacuum for pickup. See [how to use a floor buffer](/blogs/equipment-guides/how-to-use-a-floor-buffer).

The sources above address mopping, not machine scrubbing. Before running a scrubber on slate, ask the slate supplier which brush or pad is acceptable, because MSI warns that stiff brushes and scouring pads scratch slate, and test a hidden area first. Brushes are in [machine brushes](/collections/machine-brushes), pads in [floor pads and drivers](/collections/floor-pads-drivers), and pickup tools in [commercial vacuums](/collections/commercial-vacuums). For the full operating routine, see [how to use a floor scrubber](/blogs/equipment-guides/how-to-use-a-floor-scrubber).

## Are Slate Floors Slippery When Wet?

Any floor can be, especially with cleaner residue on the surface. MSI says cleft slate has natural slip resistance, and The Tile Shop says a clean-water rinse prevents a film from building up on the slate. OSHA requires workroom floors to be kept clean and, to the extent feasible, dry ([29 CFR 1910.22(a)(2)](https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.22)).

The National Floor Safety Institute publishes wet-traction resources ([NFSI](https://nfsi.org/)). If a clean floor still feels slick, ask the installer or a floor-safety specialist about traction testing.

## Frequently Asked Questions

## What is the best way to clean slate floors?

Sweep or vacuum, damp-mop with a pH-neutral stone cleaner, rinse with clean water and dry the floor. Avoid acids, abrasive tools and excess water.

## Can you use vinegar on slate floors?

No. The Tile Shop and MSI both say to avoid vinegar and other acidic cleaners, and MSI says acid etches slate and breaks down its sealer over time.

## Can you steam clean slate floors?

MSI does not recommend steam mops on natural slate, because the heat can damage the sealer bond and the forced moisture can seep into the stone and cause flaking.

## How often should slate floors be cleaned?

The Tile Shop recommends at least once a week, and more often in high-traffic areas.

## Why does my slate look cloudy or hazy after cleaning?

MSI says white haze is usually excess sealer that was not buffed off or hard-water mineral deposits. Cleaner residue also leaves a film, so rinse with clean water after mopping.

## Related Guides
- [How to Clean Ceramic and Porcelain Tile Floors: A Commercial Guide to Cleaners, Grout and Machines](/blogs/equipment-guides/how-to-clean-ceramic-tile-floors)
- [How to Clean Terrazzo Floors: A Commercial Guide to Routine, Cleaners and Machines](/blogs/equipment-guides/how-to-clean-terrazzo-floors)
- [How to Clean Polished Concrete Floors](/blogs/equipment-guides/how-to-clean-polished-concrete-floors)
- [How to Use a Floor Scrubber: Step-by-Step Auto Scrubber Guide](/blogs/equipment-guides/how-to-use-a-floor-scrubber)
- [Best Commercial Floor Scrubber: How to Pick One for Your Facility](/blogs/equipment-guides/best-commercial-floor-scrubber) [Shop Floor Scrubbers](/collections/floor-scrubbers) [Shop Floor Cleaner No.61](/products/floor-cleaner-janitori-no-61)