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Blue Denim Fabrics

History and origin of Blue Denim Jeans

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Word “denim” comes from fabric “serge de Nimes” made in France city of Nimes from where it originates. It has been used in America since the late 18th century, colored blue with indigo dye to make blue “jeans”, a type of cotton pants.

What is denim fabric made of?


Denim is a material made from 100% cotton. This is a cotton thread that is used to make a particular weave. It has warped threads in which a weft thread is placed under. This forms the traditional diagonal ribbing on the surface of the material.

What is bull denim?

Cotton Bull Denim is perfect for slipcovers, upholstery, draperies, pillow covers, headboards and much more. Bull Denim fabric is often referred to as “tough as nails” due to the strong 3×1 twill construction. Although the fabric is extremely durable it is also amazingly soft!

Why are jeans blue?

Blue was the chosen color for denim because of the chemical properties of blue dye. Most dyes will permeate fabric in hot temperatures, making the color stick. The natural indigo dye used in the first jeans, on the other hand, would stick only to the outside of the threads, according to Slate.

Definition of Denim fabrics

  • A coarse, twilled cotton fabric, often blue, traditionally used for overalls and work clothes and now used for jeans and casual wear.
  • Denim Pants or another garment made of this fabric.
  • A similar but finer fabric used in draperies and upholstery.

Denim Characteristics

  • Cotton Thread and Twill Weave
  • Denim is made from cotton, which is spun and free of any debris
  • Blue Color
  • A distinguishing feature of denim is its blue color
  • Durability: Denim is very strong and does not snag or tear easily. It is also breathable, can be ironed at a high temperature and creases easily. Suitable for long wear, it is quite stiff when new, but softens with repeated washings.
  • Raw materials used for blue denim fabrics: To produce good quality denim, the conditions have to be optimal regarding the quality of all the raw materials and yarn used. For raw cotton and the carded OE (rotor) or ring-spun yarns made from it, the quality criteria are as follows:
    • Minimum staple length: 2.7 cm.
    • The proportion of short fibers (less than 12 mm long): under 40%.
    • Micronaire value: 4.0 to 4.5.
    • The Uster values for strength and elongation, for the evenness CV and imperfections, must conform at least to the 25% plot.
    • The usual count range of denim warp yarns is 50 to 90 tex and weft yarns is 75 to 120 tex; finer yarns as fine as 25 tex in twill or plain weave are often used in denim shirts.
    • Twist factor: 4.5 to 5.0 for warp yarns, 4.2 for weft yarns.
    • Low yarn hairiness.
    • Yarn strength and uniformity.

True blue denim Fabrics are made out of 100 percent cotton warp and weft yarns. Fabrics are also made of Elastic core-spun yarns which are used as a weft yarn for textile fabrics and has gained great importance in the last decade due to the fact that stretch and recovery, comfort fits and flexibility properties.

The dual core-spun yarns are composed of cotton/ filament that contributes durability and polyurethane-based elastane that provides stretchability to the fabrics. Hereby, both filament and elastane characteristics have a great influence on denim performance at the same time. The main purpose of using this type of yarns is to achieve the effect of filament fineness and elastane draft on denim fabric performance such as braking force, breaking elongation, tear force, vertical elastic recovery, moisture management that is wicking rate and water absorption properties.

Meanwhile, filament core-spun yarns with different filament fineness and 100% cotton yarn are also used as the weft of the denim. It is found that that filament fineness and elastane draft had a statistically significant effect on all inspected performances of denim fabrics except water absorption.

Polyester blends are also manufactured and are available, however, the overwhelming majority of jeans sold are 100 percent cotton. The most common dye used is synthetic indigo.

What dye is used for denim?


The primary use for indigo is as a dye for cotton yarn, which is mainly for the production of denim cloth for blue jeans.

Why do jeans fade?

As an example, blue jeans fade where the fabric is physically rubbed. Most other natural dyes fade equally in sunlight, and minimally when rubbed. Indigo does not form a chemical bond with the fabric, like other dyes. The reduced state is also necessary because indigo cannot dissolve in water, it is insoluble

Unique Structure of Indigo dye

Indigo, or wood indigo, is a unique dye. The extraction process reflects the different molecular characteristics of indigo, as compared to other natural dyes. As an example, blue jeans fade where the fabric is physically rubbed. Most other natural dyes fade equally in sunlight, and minimally when rubbed.

Indigo does not form a chemical bond with the fabric, like other dyes. Instead, it forms a physical bond, bonding molecularly to the fabric when reduced. The reduced state is also necessary because indigo cannot dissolve in water, it is insoluble.  When the indigo molecules bond to the fabric and it is re-vetted, the indigo forms layers – like bricks. This makes indigo very impervious to sunlight, but indigo will fade with rubbing.

Reduction and Oxidization process

In the reduction vat, the indigo molecule loses an oxygen molecule.  This makes it negatively charged. When oxidized, the indigo molecules snatch back new electrons and at the same time bond to the fabric. When the fabric is re-vetted, some indigo is re-reduced but a new layer of molecules is also put down. This layer, when oxidized, then bonds to the previous layer of molecules, making a darker and more permanent color.

Extraction Methods

In the indigo, or wood indigo extraction, the molecules which form indigo, known as precursors, are soluble and extracted from the plant. During the extraction, the soluble precursors bond together to form insoluble indigo. The molecular makeup of Indigo is C16, H10, N2, O2, with double bonds on the Hydrogen. These double bonds form single bonds during reduction and then oxidize back to a double bond with the re-claiming of electrons.

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