Hard floors: why pH is the whole question

Hard floors sit alongside soft furnishings in the same trade — the UK association covers carpets, hard flooring, upholstery and curtains together — and the same rotary machines and bonnet pads are used on both. The failure modes, though, are completely different.

Textiles fail by shrinking, browning, distorting and bleeding. Hard floors fail by etching, by finish stripping, and by moisture ingress. All three are driven mostly by one variable.

pH is the variable

Acidic cleaners etch calcareous stone. Marble, limestone, travertine and concrete contain calcium carbonate, which reacts with acid. The reaction dissolves the surface, leaving a dull patch with a slightly rough texture. It is not a stain sitting on the stone — it is stone that is no longer there, and cleaning does not bring it back. Restoring an etched marble floor means re-honing and re-polishing it.

The domestic sting is that the popular “natural” cleaners are the strongest acids in the house. Vinegar sits around pH 2.5 and lemon juice around pH 2. Both are recommended constantly online as safe, natural floor cleaners. On marble or limestone they are among the most damaging things you could apply.

Acidic and solvent cleaners strip wood finishes. A sealed wood floor is protected by a coating, and the coating is what is being cleaned. Acids attack it over repeated use; once it has gone, the timber underneath absorbs liquids, stains and warps.

Alkaline and abrasive products cause their own problems — dulling, discolouration, and scouring damage that is mechanical rather than chemical.

Hence the default: a pH-neutral cleaner, at pH 7, compatible with sealed and unsealed stone alike, and safe on wood finishes. It is not the most powerful option. It is the one that does not require you to be right about the substrate.

Moisture is the second variable

Wood is porous and absorbs liquid. A wet mop leaves standing water in the seams between boards, where it soaks in, swells the timber and cups or warps the boards.

The recommended approach for sealed wood is therefore spot treatment or a damp — not wet — mop with a spray-and-wipe method, keeping the volume of water low and the drying time short. This is the same instinct as low-moisture cleaning on textiles, arrived at from a different direction: on wood, over-wetting causes structural damage rather than discolouration.

Natural stone is similarly handled with a damp cloth and a small amount of neutral soap for everyday cleaning, rather than flooding.

Where bonnet and rotary systems come in

The rotary machine and pad system used for low-profile carpet works on hard floors as well, and this overlap is why the two disciplines sit in the same trade. Cleaning solution is applied to pad and surface, the machine is run over the area, and soil transfers into the pad.

On hard floors it is a maintenance method: it lifts surface soil and refreshes appearance with very little moisture and fast drying. It does not restore an etched or worn surface, and it is not a substitute for periodic deep cleaning or re-sealing.

The practical rules

• Establish the substrate before choosing a product. Stone, sealed wood, engineered wood, laminate, vinyl and porcelain tile are five different problems.
• Default to pH-neutral unless there is a specific reason not to.
• Keep acids away from stone. Including vinegar, lemon juice and limescale removers.
• Keep water volumes low on wood, and dry as you go.
• Avoid abrasives on polished surfaces of any kind.
• Sweep or vacuum first. As with carpet, grit left on a hard floor is an abrasive that scratches the finish as soon as anything is dragged across it.