How Do High-Alkaline & Acidic Substances Cause Etching on Natural Stone?

Alkaline substances are defined by their acidity as measured on the pH logarithmic scale, which runs from zero to .14. Alkaline measures directional on a scale from .7 to .14, and acidic measures directional from .7 to .1. For the most part, alkaline substances are soluble in water and deviate from the neutral section of the pH. For example, human blood scores .7 on the pH scale, battery acid scores .1, and plumbing drain cleaner scores .14. While there are a few substances with pH levels above .14 and below 0, they’re mostly used in industrial laboratories. Within the range of the pH scale, we can classify caustic and corrosive substances. Caustic solutions are those that score above .11 on the pH scale, which means they have a high alkaline content, thus posing an etching risk to natural-stone tiles, countertops, and panels. It should be noted that corrosive substances, those that score below .3 on the pH scale, can also damage natural-stone surfaces. How the Etching Process Works Often mistaken for staining, etching happens by means of a chemical reaction from exposure to liquid acids that dull the surface. The mineral molecules of the stone react by changing color and texture. When exposed to alkaline or acidic substances for longer periods, the etching will be more severe and require more in-depth repairs. Here's a short video explaining why you shouldn't use common household cleaners on natural stone: Why Natural-Stone Surfaces React to Alkaline & Acidic Substances Virtually all types of natural stone used for interior design and decorations are of a metamorphic nature, which means their unique appearance was caused by various chemical and geological processes. After granite or marble blocks are quarried, cut, and finished, their metamorphic properties don’t stop. In other words, they don’t become impervious to chemical reactions such as etching. The Difference Between Staining and Etching Stains on natural-stone surfaces look like they were drawn. Etching has more of a watermark look. In some cases, etch marks appear to be just beneath polished surfaces, which is an optical effect caused by the resulting dullness. A pH-neutral substance such as blood only causes a surface stain on natural stone. High-alkaline and acidic substances cause etching, which can be problematic because etching has a greater potential of becoming permanent unless repaired by a stone restoration professional. Etching Risk from Common Household Cleaners Many popular cleaning products have caustic or corrosive properties ideal for surfaces such as ceramic tile and stainless steel, but they should never be used on natural stone or quartz. Some cleaners indicate their pH levels on their product labels, but others only print this information on their material safety data sheets. Your best bet is to stay away from these products and only use a specially formulated granite cleaner. Vinegar is another substance you shouldn’t use because it tends to have low pH levels. You can also use granite all-surface wipes to regularly clean the granite, marble, travertine, or other natural stone in your home, as well as quartz surfaces, stainless steel, mirrors, brass, cooktops, and more. If you’d like to learn more about the proper way to care for natural stone, reach out to the Stone Care Experts at Granite Gold® today. Call 1-800-475-STONE (7866) to speak with one of our knowledgeable representatives. If you have an Instagram account, make sure to follow us there as well for regular updates on caring for natural stone.