Study of a New Dyeing Process Based on the Capillary Rise Technique

This paper presents a new dyeing process of knitted fabric. This process consists to using a capillary rise technique with the goal to obtain a local dyeing with single color, degraded from dark to light. The C.I. Direct Red 79 dye was used in this dyeing process. The effects of dye concentration, temperature and salt (NaCl) concentration on the surface tension of the dye bath were initially investigated in order to identify the optimized parameters, required for the dyeing process. The result shows that the surface tension of the bath is almost constant when the dye concentration is varied from 0 to 12 g/L. The experimental capillarity result of salt-free bath reveals the appearance of two distinctive progression fronts. The first one, which progress rapidly through the knitted fabric, reflects the capillary progression of water. The second front, however, advances very slowly. It presents the capillary rise of the dye. When the salt is added to the bath, the capillarity result shows almost one progression front, indicating a homogeneous rise of water and dye. Likewise, color strength (K/S) investigation reveals a gradual decrease of the K/S value as a function of the fabric height. The aforementioned results highlight the use of the capillary rise technique as a simple and nondestructive method to get a dyed knitted fabric with one color, degraded from dark to light.