Cleaning polished marble

What was likely to have been on the base of the cups/glasses? Anything acid, even weakly so, for a hour or two is going to have attacked the marble itself. If the objects were the hot, is it a heat mark in any polish layer and the marble itself is OK.

You could pour undiluted household bleach on the affected area and leaving it for a few hours. It's possible that whatever caused the stain may have penetrated into the marble so you may have to allow the bleach time to work.

As an alternative to household bleach, get some sodium metabisulphite, mix it into a paste and use this instead. This is also a bleaching agent and is used in winemaking.

grind and cut back and repolish, and if you must use marble, lacquer it with a yacht varnish or something.

Its only calcium carbonate. Its porous and dissolves under any acid attack.

In that case, my suggestion of sodium metabisulphite won't be a good idea as that is slightly acidic. Domestic bleach will be ok as that's alkaline.

Surely if some of the marble has been dissolved by acid, no amount of bleach is going to undissolve it.

"Chlorine bleach, as used in household cleaning, is mainly composed of sodium hypochlorite."

Which AFAIK breaks down to give a weak Hydrochloric Acid.

Bleach works by chemically reacting with the stain to form a colourless substance. It doesn't remove anything.

Angle grinder?

In solution with water, sodium hypochlorite is alkaline.

Pressure washer!

(this is 2010, you know!)

mid.individual.net...

And domestic bleach also contains sodium hydroxide which makes it much more alkaline.

John

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You can buy it without added alkali. Milton sterilising fluid is just hypochlorite I think

On dark Granite I use bleach all the time for stains, but what caused your stain? Is it rough then maybe some gritty polish might work Maybe dab a bit of bleach and see what happens, but if it was yesterday time may dry it out.

When we had a marble fireplace installed last year, we were told by the supplier to clean it with ........ WD40! I was very sceptical at first but we've found it removes fairly stubborn stains.

Ken.

no, but it might oxidise any colouration.

T-cut will polish it back, but its hard work.

Franks one of the old school :-)

Wahoo!