Can Granite and Quartzite Etch

 

Can Granite and Quartzite Etch

Frederick M. Hueston, Stoneforensics.com

 

One of the advantages of having a granite or quartzite top is its resistance to etching.  Many stone fabricators recommend these stone for countertops due to the fact that they will not etch with common acidic food and beverages.  Acidic substances generally will not etch these stone cause they lack calcium. Calcium is the main mineral found in marbles and limestone. However, there is a substance they will produce an etch like mark on not only granite and quartzite but also on glass. This is what we call an alkaline etch. Alkaline are any chemical substance above 7 on the pH scale. Many household chemicals such as cleaners, soaps and detergents are alkaline in nature. Theses alkalis contain salts which can deposit on the surface or in the pores of the stone leaving a white haze. A good example of this is when your glasses in a dishwasher have a white cloudy film on them that won’t wipe off. This is caused by the harsh detergents in dishwashing soaps. The same reaction can take place on granite and quartzites.

How to remove Alkaline etching

Since an alkali is higher on the pH scale, an acid is needed to counter act the alkaline reaction. So a mild acid is recommend to remove the etch.  Take a rag or paper towel and soak it in white vinegar. Place the the rag on the etch and allow it to sit for several hours. The acid in the vinegar should react with the alkali salts and dissolve it. After several hours remove the rag and rinse the area with a neutral cleaner and dry. Examine the area.  In some cases the stone may need to be repolished by a professional.