Washing Processes of Denim Fabrics

A) Standard Washing:
A type of washing done with only softeners to give the sewn product softness and shrinkage. For this purpose, the following different softeners are used:

1-Cationic softeners;
They provide a soft touch in all colored cotton goods except white goods. They cause yellowing in whites and light colors. They can be easily removed from the goods by washing with water.

2-Non-ionic softeners;
They are used to soften white and light colors. Their effects are less than cationic softeners because they do not penetrate into the goods and only remain on the surface.
3-Silicones;
They give the fabric a slippery feeling in addition to softness.
4-Mixed Softeners;
Here, the fabric is given touches such as softness, slipperiness and silky air.
B) Desizing:
Denim fabric is a yarn-dyed fabric. While in hank form, it is dyed with methods such as continuous warp dye and then woven. During this weaving process, a size material that increases slipperiness and strength is applied to the warp threads to prevent breakage and dusting that may occur due to the high speed and friction in the shuttle's movements. For this purpose, starch and starch derivatives, synthetic size materials such as CMC or PVA are used. The critical point for washing starts here, because in order to perform a wash without breakage, without abrasion and with the desired touch, the size materials used must be removed. This process is very easy in synthetic sizes, because they are removed from the fabric when washed with water, but the situation changes when starch-based sizes are used, because starch; It is necessary to break down the starch since it is not soluble in water. Various methods have been developed for this purpose. The most commonly used of these methods in washing are desizing enzymes (alpha amylase). The most important problem during the desizing process is the breakage and abrasion that may occur due to the size not being removed properly and sufficiently. The most important point to be considered here is to ensure that the goods thrown into the machine do not break until they are sufficiently wet and softened a little. Because after the machine starts to turn, the goods compress each other with their own weight and since they are already hard, they leave marks where they are folded. Wetting agents and anti-breakage agents are used to reduce these problems. While wetting agents allow the goods to absorb water very quickly in the machine, they also allow other chemicals used to penetrate better into the goods. Anti-breakage agents act in two different ways.
The anti-breakage agents in the first group create a thin slippery film layer around the goods and ensure that the fold of the goods folded in the machine constantly changes. In this way, the fold does not leave a permanent mark.
The anti-breakage agents in the second group fill the gaps inside the goods, inflate the goods and thus ensure that the breakage area constantly changes.
C) Enzyme Washing:
It is done to eliminate fluffing in apparel products. For this process, biologically active acidic enzymes that are specially produced by enzyme companies and can break the chain structure of cellulose are used. As a result of this process, the pilling is removed and a shiny and smooth surface is obtained. However, it should be taken into account that the fabric weight will decrease during this process. In order to maximize the effectiveness of enzymes, factors such as pH, temperature, electrolyte and metal ion levels should be kept under control. The most important of these factors are pH and temperature. In order for enzymes to be effective, great attention should be paid to the conditions of use. Washing with anti-pilling enzymes has increased especially in recent years. Acid enzymes, which were previously used only for washing tencel fiber, are now used in most cotton product washes. It should not be forgotten that there is a risk of back-dyeing, especially in indigo dyed products. They break down the microfibrils on the surface of the product and provide a smooth surface. This naturally causes the textile material to have a softer touch. The effect obtained is a permanent effect, meaning that the possibility of the product with good anti-pilling treatment becoming pilled again after it reaches the user is greatly reduced. For an effective result, the textile material to be depilled must first be depilled, this makes it easier for the enzyme to work and reduces the risk of pilling after the product is offered to the consumer. The most important point to remember when working with anti-pilling enzyme is that there is a loss of strength during this process.

D) Stone Washing
Stone washing is a basic and important process of washing. In this washing, garment products are washed using pumice stone. The friction and rubbing of the products against each other is accelerated with the help of the stones used, and a washing effect is achieved. The resulting effect is quite superficial and brings pilling with it.

E) Dry Stone Washing (Snow Washing):

Garment products are processed in a waterless environment with stones impregnated with chemicals. Permanganate or hypochlorite is usually used as chemicals. It is a type of washing where deep point effects are obtained. In such washings, the color to be obtained after washing depends entirely on the fastness values ​​of the dyes used in the dyeing phase of the fabric against the chemicals used in snow washing. Today, the color-lightening chemicals mentioned above are also used by impregnating or mixing them with various filling materials, thus preventing problems such as holes caused by stones, especially in knitted products.

F) Stone Enzyme Washing:

In cases where deeper washing effects are desired than those obtained as a result of stone washing, neutral enzymes called stone enzymes are also used together in addition to pumice stone. The pilling problem seen in washings performed only with stones is not experienced because enzymes are used in this washing. Enzymes are protein molecules made by living microorganisms. The abrasion that occurs when enzymes are used can actually occur without enzymes. However, enzymes reduce the initial energy required for abrasion to occur, allowing abrasion to occur more quickly. In other words, they act as a catalyst in the reaction. For this reason, enzymes can be called biological catalysts. Cellulase enzymes are used in the washing of many textile products, especially denim. They break down cellulose and provide the textile product with an effect. Enzymes are used together with stones or alone during the grinding of denim products. In businesses, it is decided whether the process will be carried out with enzymes, enzyme+stones or only stones, depending on the desired effect, because there are slight differences between all of these processes. For example, every color obtained with mechanical effect is grayer and duller than the color obtained chemically (in indigo dyed goods). The factors that create mechanical effects in washing machines are listed below:

-Stone
-Washing machine speed
-Drum diameter (fabric drop height)
-Machine wing structure
-Machine drum structure (drum holes)
-Number of products and amount of water in the machine

Effects obtained chemically (with enzyme) are more specific. Another difference of the effects obtained with enzymes is that they are more vivid and bright. Especially in grinding thin fabrics, enzyme is preferred instead of stone because it is possible for stone to break thin fabrics, but another point that should not be forgotten is that if the amount and duration of enzymes are not adjusted, they will cause the product to wear out and lose strength. Enzyme and stone are used together in light-colored and high-effect goods because only in this way can the desired color and effect be achieved.

Advantages of stone+cellulase enzymes:

-Shortening washing time
-High contrast
-Vivid and bright colors
-Low wear in the washing machine
Stone enzymes can be classified in different ways. The most common classification is the classification made according to their working pH. In this way, enzymes are divided into two:

1-Neutral cellulase enzymes
2-Acid cellulase enzymes: a) acid stone enzymes, b) , Anti-pilling enzymes

G) Rinse Wash (Rinz Wash), Simple Type Rinse, Washing:
They are rinses made only for the purpose of gaining shrinkage and touch by giving the product as little washing effect as possible.

H) Fading:

While the washing effect is obtained as a result of washing with stone or enzyme stone, the color of the indigo dye used in dyeing denim fabrics can be lightened to a certain point. For washes that are desired to be lighter than this level, a fading process must be performed after enzyme washing. The fading process is usually done using hypochlorite or permanganate. After the color is obtained after the process, the residues of the chemicals used are removed from the fabric by neutralization processes. Bleaching done with hypo are usually blue-toned bleaching. It is possible to reach the lightest desired colors (ice blue) with hypo. This type of bleaching should be done in a controlled manner because hypo causes excessive loss of strength.

Neutralization process should be done with peroxide or bisulphite immediately after bleaching done with hypochlorite, otherwise yellowing and loss of strength will develop. Bleaching with permanganate is mostly used in local processes (such as spraying with a gun) and in bleaching fibers such as lycra that are damaged under the effect of heat and hypochlorite. The large size of permanganate molecules allows the color lightening process to be more controlled and slow. However, large molecules create a disadvantage in thick-stitched areas and the color remains dark in these areas.

I) Akar Dye Washing

This is the type of washing applied to products dyed using pigment dyes. Since pigment dyes are mechanically bonded to the fabric, the washing temperature and duration are adjusted depending on the amount of binder material used during dyeing and the fixation conditions.

J) Perlite Washing:

The product washed with perlite is given a well-worn appearance by giving it a shaggy, worn effect.

K) Sand Washing (Soda Washing)

A well-worn, worn, shaggy effect is given to the product by washing with chemicals.

L) Special Finishes:

They are usually acrylate or similar materials that adhere to the surface of the fabric and form a film layer. Most of the time, the purpose of use is to improve friction fastness. There are also special finishes used to increase strength or to obtain non-wrinkling and crash effects.

M) Additional Dry Processes:

Today, due to the influence of fashion, as a result of the widespread use of very used-looking clothes, processes such as moustache, rodeo, spray rodeo are also applied to apparel products. As a result of these processes, differences can be seen between products depending on the craftsmanship.

RODEO:

* Sand Rodeo: Compressed air and sand are sprayed with a special gun to the area where a worn effect is desired on the product.

* Spray Rodeo: Permanganate is sprayed with a special gun or applied with a brush to the area where a worn effect is desired on the product. Thus, the used appearance obtained is deeper and creates more contrast with the fabric color.

* Scrabbing: Instead of rodeo process with sand, it is done by hand sanding. Unlike rodeo process, it is possible to get line effects in the direction of the weft called cross effect (depending on the fabric) on sanded surfaces.

MUSTACHE:

* Sandpaper moustache: The old-looking lines that occur as a result of folds and wrinkles in long-used clothes are created on the product in advance with prepared templates.

* Spray moustache: It is a form of the processes done with sandpaper moustache, similar to the ones done with permanganate spray.

TINT DYEING:

It is an additional dyeing process that can be done after all washing processes in order to give the product a yellowed or dirty appearance. It is possible to get a dirty look in the desired color and nuance with tint dyeing.

PIECE DYEING:

It is the process of dyeing products made of raw or pre-treated knitted or woven fabrics to the desired colors with direct, pigment or reactive dyes.