Why Does Marble Stain and Etch?
- Stephanie Dasch
- 8 hours ago
- 1 min read
A certain level of vulnerability accompanies marble's beauty. Here's why marble can stain and etch.
Marble’s Composition
Marble is a metamorphic limestone, made primarily of calcite (calcium carbonate, CaCO₃). Calcite is:
Porous, allowing liquids to seep in.
Chemically reactive with acids.
Etching — A Chemical Reaction
Etching happens when acids react with the calcium carbonate in marble.
How it works:
CaCO₃ + 2H⁺ → Ca²⁺ + CO₂↑ + H₂O
The acid is actively dissolving the stone's surface, effectively eroding the polish.
Common acid sources:
Lemon juice, vinegar, wine, tomato sauce, soda
Some cleaning products
Result:
Dull spots or light, rough patches
Loss of shine — not a stain, but surface damage
Staining — A Physical Absorption Problem
Stains happen when marble absorbs colored or oily substances into its pores.
Why:
Marble’s crystalline structure has microscopic gaps that can trap pigments or oils.
Liquids can seep in before being wiped away.
Common staining culprits:
Coffee, wine, tea
Oil or grease
Metal (rust), ink, cosmetics
Result:
Discoloration that darkens or colors the stone
Prevention Tips
Apply Marble Armor stone protection film to prevent stains, etch marks, and chipping.
Seal the Stone - Sealing does not guarantee that a stain or etch won't occur, but it slows the absorption rate, giving you more time to clean it up. The sealer must be applied every 6–12 months to ensure it is effective at reducing porosity.
Blot, don’t wipe spills immediately.
Avoid acids — use pH-neutral cleaners.
Use coasters and trivets under drinks, bottles, or cookware.
