Explain why the surface of mortar and pestle (silbatta) used for grinding is etched again after prolonged use?

Question

Philoid · Accepted Answer

The surface of mortar and pestle used for grinding is etched again after prolonged use because:

⇒ The mortar and pestle lose their roughness after prolonged use (using for long time).

⇒ As a result, the force of friction decreases and they do not grind properly.

⇒ So they are etched to make them more effective for grinding again.