Q1.
Are all lustrous materials metals?
Answer
No. As the old saying goes, “All that glitters is not gold”.
- The surfaces of many materials are made shiny by polishing them, or by coating them with a thin layer of plastic, wax, lacquer or paint. A polished wooden table, a laminated notebook cover, a shiny silk saree, a glazed kulhad and a well-polished granite floor all shine — none of them is a metal.
- Some natural non-metals also shine — a diamond, a piece of mica, the mother-of-pearl inside a seashell.
And the opposite is true as well: a metal may look dull. Air and moisture act on the surface of many metals, so an old iron gate or an old copper vessel looks dull and non-lustrous. That is why we often notice the lustre only on their freshly cut surfaces.
How to be sure, then: shine alone does not prove a material is a metal. Scratch or cut the surface — a metal is shiny right through, whereas a coated object shows dull wood, paper or plastic underneath the moment the coating is scraped off.
Did you know? A brass lota that has gone dull turns bright again when rubbed with tamarind pulp or lemon and ash. You are removing the dull layer formed by air and moisture and exposing the fresh metal below.