The subject of acid on marble surfaces is a technical area that must be addressed under a separate heading from the classic stain subject. On the supply side, a significant part of the information we give our customers is dedicated to correctly explaining marble's relationship with acid. This is because this relationship is the result of a chemical reality independent of the quality of the stone, and when properly understood, no surprises occur over the years. In our three generations of supply experience, while directing Classic Marmara, Pure White, Panda, Pajama Equator, Dolomite and Homogeneous slabs from Saraylar (Marmara Island) quarries to different spaces, we have made it a discipline to discuss the issue of acid resistance at the very beginning of the project. In this article, we share marble's relationship with acid, the concept of etching, patina formation, correct cleaner selection and durability differences between honed and polished finishes.
The chemical basis of the issue lies hidden in the mineral structure of marble. Marble is a stone predominantly containing calcium carbonate. This compound undergoes a chemical reaction in an acidic environment and decomposes into carbon dioxide, water and soluble calcium salts. The reaction creates a micro-scale mineral loss on the surface, a small area of the polished bright surface of the stone deteriorates and appears as a matte mark. The technical name for this mark is etching, meaning an engraving mark. Etching is not a stain. A classic stain is pigment settled in the pore and can be removed with a cleaner. Etching, on the other hand, is the dissolution of a small mineral layer from the surface of the stone by acid and cannot be removed with a cleaner, but can only be repaired by re-polishing or honing. This fundamental difference is at the center of the initial information given to the customer.
The sources of acid in daily life are broader than most users think. Lemon juice is one of the most acidic kitchen ingredients, with a pH value around two. White vinegar has a similar acid level. Citrus fruits and juices such as orange, grapefruit and tangerine also carry an acidic character. Tomato and tomato-based sauces, although relatively low in acid load, can initiate etching if left on the surface for a long time. Some fruit juices, especially apple and grape juice, require attention due to their acidic composition. Cola, most carbonated beverages, homemade pickle juice, salad dressings, mayonnaise, ketchup and similar ingredients can also contain acid. In the bathroom environment, facial lotions, perfume-based cosmetics, acetone nail polish removers and some hair care products carry acidic structure. On the cleaning side, household limescale removers, bathroom limescale removers and some aggressive degreasers that do not contain chlorine are also sources of acid.
