Denim fabric is cent percent cotton woven fabric . Denim fabric is courser than usual woven fabric. Courser yarn is used for making denim fabric. The look and nature of the denim fabric should be enhancing subsequent to coloring. Blue denim is twist-confronted cotton fabric with 3 × 1 develops with the twist colored in strong shading and the left uncolored. Denim fabric is widely selected for its durability and appearance.
A proper finishing process is essential for the performance and the appearance of denim fabric. Finishing process of denim is critical to profits in that customers who pay the highest prices are very demanding with regard to shrinkage differences between and within fabric rolls. After weaving, the denim fabric should be mechanically and chemically treated to give it a soft and pleasant handle and correct dimensional stability. The finishing process can comprise various stages such as brushing, singeing, impregnating, stretching, drying and shrinking
Singeing:
Singeing is a process that uses a gas flame to burn off the fluff on the surface of denim fabric. This process burns away surface material that makes the fabric look fuzzy. This process enhances the color, and the fabric wet ability is also increased.
Preshrinking:
It requires very high compression at preshrinking . Fabric that does not undergo the Sanforized process and is considered raw is likely to shrink up to 10–15% on the initial wash and continue to shrink up until the third wash, and Sanforized aims to reduce the shrinkage to 1–2%.
Calendaring:
Calendaring is a process in which denim fabric is passed between rollers , under controlled heat and pressure, to produce a variety of surface textures or effects in fabric such as compactness, smoothness, glazing, etc.
Mercerizing:
Mercerization takes place in industries involving sodium hydroxide so as to increase the luster and dye ability and it is carried out after the denim is woven. It may be used for ring dyeing, keeping the dye on the surface of the yarns and to prevent dyes from fully penetrating the fibers.
Softening:
Due to the removal of impurities such as wax, paraffin and oil after per treatment processes, denim fabric loses its natural hand feel and therefore it is necessary to regain its softness. Softeners improve abrasion resistance, increase tearing strength and diminish the risk of stitching thread and needle breakage during garment sewing.
Foam finishing:
In this method, the finishing agents are added to the foam, where the moisture content is minimum. The foam is laid on a rubber conveyor, evenly across the width of the conveyor by an oscillating feed pipe system, and a blade ensures a uniform layer of foam across the width. 80% water can be saved in foam finishing.
Over dyeing:
Denim fabric can be over dyed as part of a finishing process. Over dyeing can take place between resizing and the addition of softeners. The best results, however, are achieved after stone washing and subsequent bleaching. The preparation requirements for over dyeing.