Clean printing process of cotton with natural dyes: Effect of paste formulation components on printing performances

A novel natural dye Corchorus olitorius L. was investigated in the preparation of printing pastes for screen printing of cotton fabric. To ensure ecological printing, greener thickeners were used such as: sodium alginate, carboxymethyl cellulose and Ceratonia siliqua L. flour. The nature and concentration of thickener, dyestuff and urea concentrations, mordant type and fixation method were explored. Printed cotton fabric qualities were evaluated by determining different parameters: color strength, penetration percentage, printing fastnesses and mechanical properties, whereas print paste quality was evaluated by measuring its apparent viscosity. The higher dye concentration used in the printing paste led to better apparent viscosity and color strength levels. The increase of urea concentration improved the color strength, but reduced the apparent viscosity of printing paste. Best results of viscosity and color strength parameters were obtained using ferrous sulfate as a mordant and sodium alginate as a thickener, the results being 1346.67 mPa s-1 and 4.90, respectively. The resulting color shades varied from green to brown and very good color fastnesses was achieved, but depended mainly on the used experimental conditions.