Black marks under office chairs are not dirt. They are rubber transferred by friction, sometimes with a heat glaze where the pad slid. Treating them as dirt with a mop is why they seem permanent.

Identify the mark

Mark	What it is	Removal
Grey smudge	Rubber powder on the surface	Melamine pad, light pressure
Black streak	Transferred rubber film	Solvent gel, then pad
Glossy dark spot	Heat glaze from sliding	Spot polish with 400-800 resin
Ring outline	Pad edge, repeated contact	Combination: solvent, then polish

Removal sequence

1. Dry wipe first; solvent on loose rubber spreads the mark.
2. Apply a small amount of appropriate solvent gel to the mark only, wait 30-60 seconds.
3. Wipe with a clean white cloth, turning to a clean face each pass.
4. Use a melamine pad on residue, with light pressure and a small area at a time.
5. Buff the area to restore sheen, then compare gloss under the same angle.

What not to do

• Do not use acetone or lacquer thinner; they soften the sealer and leave a dull patch.
• Do not scrub with a black pad; it cuts the cream and creates a permanent light spot.
• Do not use steam; heat sets rubber deeper into the pore.
• Do not acid wash; it does nothing to rubber and damages the finish.

Prevention is cheaper

Specify soft polyurethane or nylon castors rather than hard rubber, and add chair mats under the highest-use desks. A 1.2 m mat under each workstation removes most of the marks and costs less than one deep clean of the floor.

For facilities teams, a monthly walk with a melamine pad and a solvent gel handles the whole floor in an hour. Waiting until marks are black and glazed triples the work.