“…In the past, before the invention of synthetic molecules and after the discovery of mauveine by Perkin, only natural compounds were used to dye, which were extracted from plants or animals such as madder, indigo, cochineal, and so on. , It was also discovered that craftsmen used a metallic salt to produce a more stable and intense color in the textile, for instance, alum, AlK(SO 4 ) 2 , 12 H 2 O, was in use at the least since Roman times. , Indeed, most of the dyeing molecules cannot bond strongly enough to the textile fibers because of the relative weakness of van der Waals interactions . However, they can combine with a metallic salt fixed in the fibers, that is, a mordant, because their structure has one or more chelation sites.…”