Linen fabric dyeing can be carried out by continuous pad dyeing, jig dyeing, overflow jet and other methods. The open-width method is better because it is less likely to cause scratches and color streaks.
The main component of hemp fiber is cellulose, with a content of 70-80% and a white color. In addition to cellulose, it also contains hemicellulose (12-15%), pectic substances (1.4-5.7%), lignin (2.5-5%), nitrogen-containing compounds (0.3-0.6%), and fatty waxes (1.2 -1.8%). These impurities directly affect the physical and mechanical properties of hemp fiber, reduce the wettability of the yarn, and make the hand feel rough and the color yellow. The impurity content in hemp fiber is significantly higher than that in cotton fiber, which increases the difficulty of the bleaching process of hemp fabric and makes the hemp fabric less bright in color and poor in dye fastness after dyeing. Therefore, during the dyeing process, reactive dyes should be used for light and medium colors, and vat or liquid sulfur dyes can be used for dark colors. Applicable reactive dyes include M type, ME type, RH type and RM type from Shanghai Dyeing and Chemical Factory No. 8, etc. In addition, linen fabrics have a higher degree of crystallinity, making them more difficult to dye than cotton and prone to wrinkles, resulting in uneven dyeing. It is better to use dyes with good leveling properties and higher dyeing temperatures.
When finishing hemp fabrics, chemical and mechanical methods can be used. Chemical softening finishing equipment can be used such as hot air tenter machine. Mechanically soft equipment can be processed in wet or dry ways according to different requirements.