PIGMENTS

Pigments as a class  are colored  materials  that  are  insoluble    in their  medium  of  application. As a  result,  they cannot penetrate or become readily   fixed to a  fiber  and  must  be  "locked"  onto  the  fiber  surface by use of a  polymeric adhesive binder that  encapsulates  and  holds   the pigment  onto the  fibers. Pigments  include inorganic salts,  insoluble azo  or  vat  dyes, toners, lakes, metallic  complexes,  and  organ metallic  complexes. Some binders are  preformed  water-insoluble  polymers   applied  from  solvents or  as emulsions,   whereas  others are  water-soluble or emulsifiable polymers which can  be chemically crosslinked  and  insolubilized  after  application  by  drying and  heating. The  pigment binder systems   tend  to  stiffen textiles,  and  have moderate   to  poor  fastness,  since  they  are  surface  treatments.