dye concentration in the bath is 0 4 pbw but there is considerable latitude in this regard generally dyes may be present in the solvent mixture at a level of about 0 1 to 15 pbw preferably 0 3 to 0 5 pbw where a dye mixture is used and the rates of consumption of the individual components differ one from the others dye components will have to be added to the bath in such a manner that their proportions in the bath remain substantially constant the bath may optionally include an emulsifier in amounts of up to 15 pbw preferably 0 5 to 5 most preferably 3 to 4 pbw a suitable emulsifier in the context of the invention is a substance that holds two or more immiscible liquids or solids in suspension e g water and the carrier emulsifiers which may be used include ionic non ionic or mixtures thereof typical ionic emulsifiers are anionic including amine salts or alkali salts of carboxylic sulfamic or phosphoric acids for example sodium lauryl sulfate ammonium lauryl sulfate lignosulfonic acid salts ethylene diamine tetra acetic acid edta sodium salts and acid salts of amines such as laurylamine hydrochloride or poly oxy 1 2 ethanediyl alpha sulfo omega hydroxy ether with phenol 1 methylphenyl ethyl.