The purpose of the diploma thesis was to show the usefulness of natural dyes obtained from the green leaves of Staghorn sumac and autumn-coloured reddish leaves of Japanese knotweed for the preparation of printing ink intended for screen printing on paper and textiles. Four printing inks were prepared from dyes of Staghorn sumac leaves extracted in ethanol and dichloromethane and one printing ink from dyes of Japanese knotweed leaves extracted in acetone. Various printing materials were used for printing, including commercial white paper, paper from the stems of Goldenrod, paper from the stems of Japanese knotweed, and cotton and polyester fabrics. The prints were colorimetrically evaluated and tested for resistance to abrasion and light, and on fabrics for household washing and ironing. The colour of prints from the Staghorn sumac green leaf extract were different shades of green. The colours of prints were more intense with the dye extracted in ethanol than in dichloromethane. The addition of soda increased the intensity of the printed colour and impaired resistance to washing and light. The prints of yellowish-orange colour were obtained with the printing ink from the extract of reddish leaves of Japanese knotweed. The fastness of the prints on all printed materials was very good to rubbing and a little worse to light. The fastness of the prints from Staghorn sumac leaf dye on the cotton fabric were very good to washing, wet ironing and wet rubbing. Slightly better fastness of the prints was achieved with the dye extracted in dichloromethane than in ethanol.
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