If this is your problem, here's your solution.

That round stain is a typical case of corrosion.

Marble corrosion is caused by a contact, albeit brief, with weakly acidic liquids as well.

How to distinguish etch marks from other spots?

• They have an opaque whitish appearance
• They are more or less rough to the touch
• They can not be removed with normal detergents, solvents or stain remover
• Even if they are slight, they are always visible in backlight

Why do they take shape?

Marbles, as well as travertines and limestone stones, are very sensitive to the aggression of the acids which cause their disintegration.

What really happens when an acid "attacks" the surface of the marble?

The acid is combined with calcium carbonate molecules, which are abundant in marble, "eating them". So many "holes" remain on the surface and polishing is lost.

How can we fix it?

The answer is plainly simple:

           Polishing must be done again!

There is no alternative to restoring the surface to its original state.

To obtain the polishing of the marble again, two steps are expected:

It is important for you to know that in the case of slight corrosion is enough the only chemical step. Everything can be solved in a matter of seconds!

Chemical polishing can be resolved without the use of abrasives when the "holes" that have been formed from the acid have molecular dimensions. Only in this case the "calcium oxalate" molecules, which are formed during the application of the polishing product and are stably combined with the "calcium carbonate", are able to fill all the "empty holes" perfectly.

Note that chemical polishing is a real polishing in every aspect! It is not obtained by "painting" the marble with a crystallizing product!

When the "holes" excessively exceed the molecular dimension, mechanical action is required to smooth the surface too corrugated.

Depending on the depth of the "holes" you will have to choose the grain of the abrasive that can smooth the surface with acceptable effort and times.