Sodium metabisulfite (Na₂S₂O₅) is commonly used for chemical washes of ornaments, particularly metal ornaments, for several reasons:
* Cleaning: It acts as a reducing agent and can remove tarnish and oxidation from metals like silver, copper, and brass. This is because it reacts with the oxides and sulfides on the metal surface, converting them into soluble compounds that are then washed away.
* Disinfection: Sodium metabisulfite also has antibacterial and antifungal properties, making it effective at killing microbes and preventing the growth of mold or mildew on ornaments.
* Safety: Compared to stronger acids or alkalis, sodium metabisulfite is generally considered safer and less harsh on delicate ornaments.
Important Note: While sodium metabisulfite is generally safe for cleaning, it's essential to follow proper handling and safety procedures. It can irritate the skin and eyes, so gloves and eye protection are recommended. It's also important to rinse ornaments thoroughly after the cleaning process.
Sodium pyrosulfate (Na₂S₂O₇), on the other hand, is less commonly used for cleaning ornaments. It's primarily used in industrial processes like metal processing and glassmaking.
