Denim is yarn-dyed and mill-finished and is typically made of cotton, however a cotton-synthetic fiber blend is used in large numbers. Denim's durability has been shown over decades of usage in the apparel business, particularly in the production of overalls and trousers worn for hard labor. The term "denim" comes from the French word denier, which means one-thousand.
Today, most denim on the market is made from 95% cotton and 5% elastane. Older styles of denim may contain up to 40% linen or 50/50 cotton-linen blends.
All dyed fabrics require some type of finishing process to make them durable enough for use in clothing. This usually involves some type of heat treatment that creates a soft handle in the fabric for easier careening (dyeing) later if it isn't done already. Most modern denim is finished after dyeing with a chemical called dioxan. This process removes most of the water content from the fiber so it will dry more quickly when painted with additional dye baths. It also makes the fiber softer when wet and harder when dried. Some older styles of denim may be finished with a boiled process instead. In this case, the water content is removed before dyeing by placing the fabric in a vat of sulfuric acid and boiling it for several hours. The sulfuric acid changes the color of the cellulose fibers in the denim without removing much moisture at all.
Denim is, in reality, a cotton byproduct cloth. It is distinguished from other cotton items by its weave style and finish. Denim is made with thick cotton yarns in a special weave called twill. Denim is not the only fabric used to make jeans, but it is the most popular and well-known. Other materials used in making jeans include plastic, rubber, metal, and hemp.
All types of cotton are natural products composed of long fibers that contain cellulose molecules. Some varieties of cotton are more refined than others. Refined cottons are usually stronger and have a better color range than less refined types. Today, almost all denim is made from refined cotton. However, earlier types of denim were made from less refined cotton. This means they had more natural colors and were softer to the touch.
Refinement of cotton affects how it is processed after harvesting. Less refined cotton is picked before it has matured completely, so some of its seeds will still be present. These seeds are difficult to remove during processing steps such as ginning and spinning so they end up in the final product. The term "seed cotton" refers to cotton that has not been fully harvested. This type of cotton is used for making garments with longer production times because it can't be spun into usable fiber quickly like seedless cotton can.
Seed cotton does not affect the quality of the finished garment because it is removed prior to sewing.
Denim is a tough, cotton twill fabric that is often used in jeans, jackets, overalls, and other sorts of apparel. The term "denim" comes from the French language meaning "dyed cloth," which describes the process of making this fabric. The dye used for denim comes in two main types: natural and synthetic.
Natural dyes are derived from plants or minerals and include food-dye colors such as black, blue, brown, gray, green, orange, red, white, and yellow. When applied to textile fibers, these dyes produce colors that vary depending on the type of fiber (for example, black for cotton, brown for hemp), so they are usually combined with other dyes to create different colors. For example, red chile peppers contain three primary colors (red, yellow, and blue) that can be mixed to make many other colors. You can mix natural dyes yourself, but it's not easy - the results depend on how much you overdye your material. For example, mixing just one part blue cornflower to four parts white will give you sky blue, but mixing the same amount of blue cornflower to eight parts black indigo will yield violet.