… cloth before dying it using seawood from their coast. Later they would use chlorine. The MORDANT was being developed in many places and from many sources.
A MORDANT was a substance used to precondition fabric so that its specific pH (acidity or alkalinity) would alter the chemistry of the fabric so the dye would adhere and absorb differently depending on the application.
(Photo: typical mordants and their effect on cochineal dyed yarn)