The grounds lane is retained. It builds up as a reserve of the pair asset held by the coin's contract and it backs a floor price.
floor = grounds รท circulatingSupply
The floor rises at every pour that sends anything to grounds, because grounds grows and supply does not. It rises when tokens are burned without redeeming, because supply shrinks and grounds does not. It stays exactly where it is when someone redeems, because they take out precisely their share of grounds and remove precisely their share of supply. There is no operation in the contract that lowers it.
During scald, everything collected above the creator's tax goes to grounds. A coin that gets hit hard in its first two hundred blocks starts life with a floor already under it.