First of all there is a big difference between stains and etching. Stains are caused by any agent that has penetrated into the pores of the stone (oil, grease, make up, sauces, etc). A stain will always be darker than the stone.
.Etching is caused by an acidic substance coming into contact with a calcite based stone (marble, limestone, travertine, etc). Etching is a chemical reaction in the stone caused by the acidic substance; etching will always be lighter than the stone.
Ok- so now that we understand the difference between a stain and an etch (stain-darker than the stone, etch-lighter than the stone), we now have to determine which product to use. Removing a stain is quite straight forward; you will need to use a poultice. What is a poultice? It is the combination of a very absorbent medium (it must be more absorbent than the stone) mixed with a chemical, which is to be selected in accordance with the type of stain to be removed. The concept is to re-absorb the stain out of the stone. The chemical will attack the stain inside the stone, and the absorbent agent will pull them both out together. A poultice can be used on all natural stones without worrying about etching or further damage.
The polishing powder used to remove a “stain” would not have worked in this instance. Polishing powders are used to remove etch marks; remember- etching chemically changes the appearance of the stone. So while the area the stone polished was used on would be nice a shiny, the stain would still remain.
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