A new earthern pot cools water better than old pot.why?

Question

A new earthern pot cools water better than old pot.why?

Answer 1

Earthen pots cool by allowing a little water to seep to the outer surface where it is evaporated, and this cools the pot and contents:  I guess an old pot may build up residues which prevent the water from seeping through, hence reducing evaporation.  This principle was used to keep things cool before refrigeration - a cupboard was build with double walls of chicken wirte, and coke (coal which has been partially burnt)was put between the layers - water was dripped onto the coke, which has a very porous structure, and the evaporation of the water kept the cupboard cool.

Answer 2

  The inside of the pot builds up residue over time creating an insulating lair and prevents heat from escaping.