Marble polishing or crystallisation?

What is the difference between polishing and crystallisation?

They are two different jobs that are often sold under one name. Polishing is mechanical. A weighted machine turns diamond abrasive pads on the wet floor and removes a very thin layer of stone, taking scratches and surface stains away with it. The shine at the end is the stone itself, cut so fine that it reflects.

Crystallisation is chemical. A crystallising liquid is sprayed on and worked in with a steel wool pad. Friction heats the surface, and the liquid reacts with the calcium carbonate in the marble to form a harder, glossier skin. Nothing is removed, so nothing is repaired. A scratch that was there before is still there afterwards, only shinier.

How is diamond polishing carried out?

• Furniture and rugs are cleared, and skirting, door frames, joinery and glass are masked with tape and plastic sheet to knee height.
• Open joints, chips and holes are filled with a resin tinted to the stone and left to cure.
• Where tile edges sit at different heights, the floor is ground flat with coarse metal bonded diamonds. This step is skipped on a floor that is already level.
• The floor is honed with resin bonded diamond pads through a run of grits, coarse to fine. Each pass removes the scratch pattern left by the one before, and a skipped grit shows later as haze.
• Slurry is collected with a wet vacuum after every pass and the floor is rinsed, so that coarse grit is not dragged under a finer pad.
• Edges, corners and stair treads, which the large machine cannot reach, are done with a hand machine using the same grits.
• The final gloss comes from the finest pads or a polishing powder worked with a little water.
• When the stone is dry, an impregnating sealer is applied and the excess buffed off. It slows staining. It does not make marble proof against acid.

How is crystallisation carried out?

The floor is first cleaned, stripped of any wax or old coating and allowed to dry fully, because moisture trapped under the treated surface causes cloudy patches. The liquid is sprayed over a couple of square metres at a time and worked at once with a steel wool pad under a heavy single disc machine until the surface is dry and glossy. The operator moves on section by section, then goes over the whole floor with a clean pad and removes every strand of steel wool dust, which would otherwise rust on a damp floor.

Done at sensible intervals on sound marble, it keeps a lobby or living room bright between polishes. Done again and again in place of polishing, it builds an uneven layer that yellows, shows scratches as white lines and has to be ground off before the floor can be restored. It does nothing on granite, quartzite, porcelain or engineered quartz, which have no calcium carbonate for it to react with.

Which treatment does my floor need?

Crouch at a doorway and look across the floor towards a window. The low angle shows everything.

• Dull paths where people walk, with the shine surviving under furniture: the surface is worn and needs honing and polishing.
• Rings and splash shaped dull marks near the dining table, the bar or the kitchen: acid etching from juice, wine or a cleaner. Polishing removes it.
• Scratches you can feel with a fingernail: grinding, starting from a coarser grit.
• Tile edges that catch a coin slid across them: the floor needs flattening before it is honed.
• An even floor with no marks that has simply lost its sparkle: a light polish or crystallisation is enough.
• Dark or yellow stains that sit deep in the stone: these need a poultice, and the result cannot be promised until one has been tried.

Why does marble lose its shine so quickly in Dubai?

Fine sand is the main cause. It comes in on shoes and through balcony doors, and the grains are harder than marble, so every footstep works like fine sandpaper. Entrances and the route from the terrace to the kitchen go dull first. Cleaning products are the second cause. Bathroom descalers, bleach, vinegar and many general purpose floor cleaners are acidic or strongly alkaline, and they etch the surface a little with each wash. Hard water adds limescale around showers and on bathroom floors, and the acid cleaners sold to remove it attack the marble under the scale.

Mop water does the rest. A mop rinsed in the same bucket spreads a thin film of dirt and detergent that dries to a haze, and people respond by using more product.

How do I look after the floor afterwards?

• Put a mat outside and inside every external door, and shake them out often.
• Dust mop daily with dry microfibre, so that sand is lifted before it is walked in.
• Wash with a pH neutral stone cleaner in clean water, change the water often and wring the mop well.
• Blot spills at once, especially citrus, vinegar, wine, coffee and perfume.
• Fit felt pads under chairs and tables and replace them when they collect grit.
• Keep descalers and bathroom acids off marble altogether.

The MELLS inspects the floor at a site visit and gives a written quotation that states which process each room will receive, and a supervisor checks the finished floor against before and after photographs.