How To Clean Marble Surfaces In a London Bathroom Without Etching Them
The worst marble I have ever seen was in a converted warehouse flat off Kingsland Road in Dalston. Polished Carrara vanity top, about two metres of it, with a constellation of dull white rings across the whole surface where the owner had been standing a limescale spray bottle down after use. The bottle leaked slightly around the trigger. Eighteen months of that, and the top was finished.
She had done everything a sensible person does. Wiped up promptly, used a branded bathroom product, kept it dry. The product was the problem, and nobody had told her.
What Happens To Marble When It Etches?
Marble is limestone that has been cooked and squeezed under a mountain until the calcite recrystallised. Chemically it is still calcium carbonate, which means it behaves like a very expensive antacid tablet. Put an acid on it and the acid reacts with the calcium carbonate, dissolves a shallow layer of it, and releases carbon dioxide in the process. On a honed surface you sometimes see the fizz.
What you are left with is a crater. A very shallow one, thousandths of a millimetre deep, but the polished surface that used to sit there has gone into solution and left a rough matte floor behind. Light hits it differently. That is the whole mechanism, and it takes about fifteen seconds.
No cleaning product reverses it, because there is nothing on the surface to clean off.
How do you tell an etch from a stain?
Look at it from an angle with a light source behind you. A stain sits in the stone and shows as a darker patch that persists whatever the angle. An etch shows as a dull patch that appears and disappears as you move your head, because you are seeing a change in reflectivity rather than a change in colour.
Run a fingertip over it dry. Etching often has a faint drag to it that polished marble does not. Stains feel like nothing.
I get called out to stains and find etching about four times out of five in London bathrooms, and that conversation is one of the least enjoyable parts of the job. Ask me how I know.
Why Is a London Bathroom the Worst Possible Room For Marble?
Because the water that comes out of the taps in Ealing and in Bexleyheath alike is loaded with dissolved calcium, and that calcium deposits itself as limescale on every surface it evaporates from, marble included. So within a fortnight of installation you have a chalky film on your beautiful vanity top and an instinct to reach for something that removes limescale.
Every product that removes limescale is an acid. Limescale is calcium carbonate. Marble is calcium carbonate. The descaler cannot tell them apart and it will take the polish off the vanity faster than it takes the film off.
That trap catches homeowners, tenants, and a distressing number of cleaners who ought to know better.
Which bottles in your bathroom are doing the damage?
The obvious ones are the limescale and shower sprays, the toilet cleaner that gets flicked onto the floor tiles by the brush, and anything sold as a natural alternative on a base of vinegar or lemon.
The ones people never think of are personal. Toothpaste with whitening agents in it, spat and left overnight in a marble basin. Salicylic acid face wash. Glycolic toner. Vitamin C serum, which is ascorbic acid at somewhere around pH 3 and eats marble very efficiently. Benzoyl peroxide acne cream, which bleaches as well as etches. Hair dye and its developer, on a splashback behind a mirror. Perfume, which is mostly alcohol but usually carries something acidic with it.
A client on Bellenden Road in Peckham had a perfect ring on her marble shelf the diameter of the base of a Chanel bottle. It sat in that one spot for two years. There was nothing to be done about it short of refinishing the whole shelf.
What Should You Be Cleaning It With Instead?
Warm water and a pH-neutral cleaner formulated for natural stone. That is the answer, and it disappoints people, because it sounds like an absence of a solution rather than a solution.
The routine that keeps marble alive is boring and it goes like this. Dust the surface dry first with a microfibre, because London bathrooms accumulate grit and hair and skin cells, and dragging a wet cloth across grit is how you put fine scratches into polished stone. Then wipe with a barely damp cloth and your neutral cleaner. Then dry it properly with a second cloth, which stops the hard water leaving the film that started this whole chain of trouble.
Twice a week takes four minutes. It also means you never need a descaler in the room at all, which is the point.
Stone soap is worth knowing about for honed marble specifically. It is a mild alkaline soap that leaves a very thin fatty residue, and on a honed surface it builds a slight sheen and some resistance over months of use. On polished marble it can look smeary, so I use it selectively.
Things that go nowhere near it: bleach, which will not etch but will dull and can yellow the resin fills in Calacatta over time; ammonia; anything with a cream abrasive; melamine sponges, which are ultra-fine sandpaper and will hone a polished edge in about thirty seconds.
What do you do about soap scum, which is the real job?
Soap scum on marble is the problem that generates most of my callouts, and the reason is that scum is a fatty deposit bonded up with hard water minerals, and every standard fix for it is an acid.
Work alkaline instead. A dilute stone-safe alkaline degreaser, applied warm, given eight or ten minutes of dwell time, then agitated with a soft nylon brush along the grout lines and rinsed thoroughly. Heat does most of the lifting. Where it has gone hard and waxy on a shower kerb, a plastic razor blade held nearly flat will shift the bulk of it without touching the stone, and I would rather use that than any chemical.
Then swap the soap. Bar soap is the primary cause and a liquid body wash produces a fraction of the scum on the same water. Half the marble shower enclosures I look after in Blackheath and up around Wightman Road in Harringay would look twice as good with that one change and no additional cleaning.
Does Sealing Protect Marble From Any Of This?
Sealing protects against staining. It does nothing whatsoever about etching, and the number of installers who let clients walk away believing otherwise is a small scandal in the stone trade.
An impregnating sealer soaks into the pores of the stone and lines them so that oil and pigment cannot get down into the structure. Acid attacks the calcite that makes up the stone itself, which the sealer is sitting inside rather than on top of. Acid goes through it as though it were not there. Ask me how I know: I sealed a sample offcut of Statuario properly, left it a week to cure, and dripped lemon juice on it. Etched in twenty seconds, same as the unsealed half.
Seal anyway. Staining from oils, cosmetics and hair dye is permanent in its own way and a sealer prevents most of it. Reapply every year or two on a bathroom vanity.
Should you have specified honed rather than polished?
Yes, and I will say that plainly rather than hedge it. Polished marble in a London family bathroom is a decorative choice that begins deteriorating on day one, because polish is the thing that etching destroys and a honed surface has nothing to lose. Etch marks on honed Carrara are close to invisible until you get a serious one.
If you are still at the specification stage, hone it. If somebody has already fitted polished Calacatta across your en suite on Amwell Street in Clerkenwell, you are committed, and your routine has to carry the difference.
Can You Repair Etching Yourself?
Sometimes. Light etching on polished marble responds to marble polishing powder, which is a fine abrasive compound worked with a damp cloth or a low-speed buffing pad in small circles until the shine comes back. Kits cost about fifteen pounds. On a single ring from a toothpaste blob, it works.
Deep etching, wide etching, or anything on honed stone needs a stone restorer with diamond abrasives who will grind and refinish the whole panel to a consistent finish. Spot-repairing a honed surface leaves you with a patch that is shinier than everything around it, which reads worse than the etch did.
That is the boundary of what a cleaning contractor should be selling you. My firm cleans stone and maintains it, and when I look at a vanity in Kilburn with forty rings across it I tell people to ring a restoration specialist, because the alternative is taking money for a deep clean that will change nothing. Ask me how I know.
What does a maintained marble bathroom look like after five years?
Slightly softer than the day it went in, and that is the correct outcome. Marble is a surface that records its use. The vanity in a Richmond house I have looked after since 2019 has two faint etch marks near the tap and a very slightly muted sheen along the front edge where forearms rest, and it looks better for it than a slab of quartz that has recorded nothing.
What that house does differently is small. Neutral cleaner under the sink and no descaler anywhere in the room. A microfibre folded on the rail. Bottles standing on a marble offcut the fabricator left behind, which absorbs the damage instead of the top. Nobody in that family knows the chemistry and nobody needs to.
Keep a coaster in the bathroom. A coaster, for the perfume and the mouthwash and the face wash bottle, and half of everything above stops happening.