This paper is concerned with the quality of lines and disperse ink in printing patterns on different untreated polyester fabric constructions. The lines running in the weft and warp directions were printed on polyester fabric constructions, and printing accuracy was assessed. Ink spreading is one of the important factors that influences the ink distribution. Thus, in order to acquire satisfactory ink-jet printing products, it is essential to control the spreading of ink on the polyester fabric. To meet these conditions, a series of chemicals (disperse dye 5.01 wt%, PVP-K30 0-2 wt%, DEG 5-20 wt%, water 64.17-79.17 wt%, etc) with different mass fractions was used to prepare disperse ink. The jetting behaviour of ink was related to its surface tension and viscosity, which was characterised by an automatic surface tensiometer and rotational viscometer. Line profile was used to evaluate the printing effect. Low field nuclear magnetic resonance and three-dimensional super depth digital microscopy were used to reveal the relationships between the state of water, ink diffusion behaviour and printing sharpness. The results showed that increasing ink viscosity or decreasing free water content is advantageous to improve the sharpness of the printing pattern.The effects of fabric structural parameters on line image quality are discussed. The printing quality was closely related to the weight and structure of fabric. The heavy weight fabrics had accurate print pattern sharpness. The fastness test results showed that the ink printing pattern had good colour fastness.How to cite this article: Gao C, Xing T, Hou X, Chen G. The influence of ink viscosity, water and fabric construction on the quality of ink-jet printed polyester. Coloration Technol. 2020;136:45-59.