Nature of reactive vs brand dyes :(bi-sulfatoethye sulfone class) these dyes are vinyl sulphone as the reactive group. In presence of alkali, these dyes chemically react with the hydroxyl group of cellulose and form firm, convalent linkages. Very versatile to suit different dyeing methods, with result excellent and shades are clean and brilliant with no variation of dyeing or either at printing. Vs dyestuff carries poor affinity for cellulose fibers in absence of salt and alkalis. As such, suited for use on pad. Their substantives can be increased by addition of glauber's salt or common salt and alkali, and suitable on all conventional dyeing machines for loose material, yarn in hanks and packages and piece goods. Dyeing methods hence are classified as the padding and exhaust processes. Standing baths are not recommended, as side reaction occurs because of alkaline medium inactivation of the dyes by reaction with water takes place. The important features of vs dyes are: excellent brightness and good wet fastness. fare dischargeable. most suitable for exhaust & different pad dyeing methods and discharge printing. ease of washing off unfixed dyestuffs i.e. Minimum staining of the white grounds in printing. applicable at 40oc and 60oc.