Denim Manufacturing Basics

Overview of Denim Manufacturing

Warp yarns used in indigo denim fabrics must go through numerous processing steps before they are ready to be woven. These processing steps are unique to indigo fabric manufacturing. Most often the warp yarns are indigo dyed on a system referred to as a long-chain or rope range. For this system, multiple ends of yarn are formed into a rope or ball warp and then continuously dyed.

After dyeing, the dyed ball warp is rebeamed into individual yarns evenly spaced onto beams called section beams. These beams are then slashed and then woven. If the warp yarns are to be slasher or sheet dyed, then the yarns will be warped onto section beams and indigo dyed. In most cases, the yarns will also be slashed or sized in the same process. The yarn is then woven. If the warp yarns are to be beam dyed, then the yarns are warped onto perforated dye beams for dyeing instead of being formed into ropes.

After beam dyeing, the dyed yarn is then slashed and woven. If it is chosen to have natural warp yarns, then prior to weaving the yarns will be warped onto section beams then slashed and woven. The fabric is then processed in a normal manner. This would include desizing, preparation, dyeing (if desired), and finishing. Unlike the warp yarn, mot filling yarn is put onto yarn packages and delivered directly to the weaving machine where it is inserted into the fabric without any wet processing but sometimes dyed filling yarns are used to achieve a different looking denim.

Denim Construction, Weaves, & Weights

The weights of the finished fabrics vary between 3.5 and 16.5 ounces per square yard. The fabrics weighing 3.5 to 8 ounces per square yard are typically used to manufacture blouses, tops, and shirts. Trousers, jeans, and jackets tend to use heavier weight denim fabric ranging between 8 and 16.5 ounces per square yard.

Numerical notations for different denim designs, such as 3 X 1 twill, denote what each warp yarn is doing relative to the filling yarns interlacing with it.

In this example, look at the end marked number 1. This warp yarn is going over picks 1, 2, and 3 and then under pick number 4. We see that with the end marked number 2, the same sequence is being repeated but advanced up one pick. This means that the warp yarn is under pick number 1 and goes over picks number 2, 3, and 4. This upward advancing sequence continues, thus giving the characteristic twill line. In this case, the twill line would be rising from the lower left to the upper right and the fabric would be classified as a 3 X 1 right-hand twill weave. If the twill line is made to rise to the left, then the design is a left-hand twill.

Non-Conventional Denim Fabrics

Non-conventional denim fabrics include: