Medium-low viscous thickener for direct printing on cellulosic fibres with reactive dyes, based on pure sodium alginate. As sodium alginate is a naturally biodegradable polymer, the thickener is most ecological in use for reactive printing. Due to the very good flowablitiy, the thickener will show a very good penetrating behaviour. This will help to print with higher speed on rotary printing machines, increases the penetration of print paste on knit fabrics and also increases print quality by using fine mesh screens. The washablility and the viscosity stability of this grade are superior.