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


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.


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