The purpose of the diploma thesis was to investigate the influence of different printing pastes and additives on the colour and fastness of prints obtained with printing inks prepared with natural dyes from the rhizome and leaves of Japanese knotweed. Four different types of printing pastes and various additives in the printing paste, such as: soda, citric acid, copper sulphate, iron sulphate, aluminium sulphate, fluorescent bleaching agent and fluorescent pigment were used for the preparation of printing inks. The main goal was to test the applicability of prepared printing inks for screen printing on various printing materials by spectrophotometric analysis of print quality and by testing the fastness of prints to rubbing, light and on fabrics as well as ironing and washing. The printed materials used were Japanese knotweed rhizome paper (grammage of 240 g / m2), commercially recycled and bleached paper (both grammage of 200 g / m2) and polyester and cotton fabrics.
The fastness of the prints on dry rubbing on papers and fabrics is excellent. Resistance to wet rubbing on fabrics is slightly worse, the worst for the prints obtained with printing inks with the addition of alkali and metal salts. The fastness of prints on wet ironing is good and worse on washing. Various additives and printing pastes did not improve the durability of prints on wet treatments. The light fastness of the prints is poor on all printing materials. The light fastness of the prints is significantly improved by the addition of citric acid and copper sulphate.
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