Dye exhaustion and Dye substantivity

Dye exhaustion

In long or short liquor dyeing process it is required minimum dye molecules in dye bath to colour aimed textile materials. But if dye molecules in one liter are not enough to fulfill that minimum required level, then fabric will not be dyed. Therefore optimum dye concentration is needed. It is known as dye exhaustion. Dye exhaustion can be calculated using following formula.

In another word I can explain that in single dye minimum proportion to colour textile material by substrate that amount originally availability of dye bath.

 

Dye substantivity

In the term of substantivity we can get a clear idea and, it means the amount of dye attraction of textile material is called substantivity of dye. If dye has higher substantivity then greater attraction of dye and textile material will be occurred. But in low substantivity then attraction of dye with textile material will low. Therefore to improve substantivity, some wetting agents, common salts, dye solubility agents are added into dye bath.