Monday, January 1, 2018

Stone Washing Process

Stone Washing:
Stone washing is a textile manufacturing process used to give a newly manufactured cloth garment a worn-in (or worn-out) appearance. To achieve the desired stone washing effect for the garments, the stone should be of proper hardness, shape and size. It is a popular wash for denim or canvas fabric.

A number of people and organizations have claimed to have invented stone washing:
  • According to Levi Strauss & Co., Donald Freeland, an employee of the Great Western Garment Company (later acquired by Levi’s), invented ‘stone-washing’ denim in the 1950s.
  • Inventor Claude Blankiet has also been credited with having invented the technique in the 1970s.
  • The jeans company Edwin claims to have invented the technique in the 1980s.
  • In 1982, Lee introduced ‘stone washed’ jeans. This was followed by ‘acid-washed’ denim, which produced an even more faded look.
Stone washed denim gained popularity in the 1960s and remains popular to this day. This type of denim is characterized by a lightly distressed, vintage look. The name comes from the fact that the original processing method involved rubbing pumice stones over the denim to wear down the fabric. Pumice stones are the silica-rich, high-temperature melted product of explosive eruptions during the ascent and expulsion of the earth. These are lightweight, highly porous, rocky substances which will float on water. Major pumice stone–supplying countries are the United States, Turkey, Italy, Iceland, New Zealand, Japan, Indonesia and the Philippines. It is an important component of stonewashed apparels and is used to abrade the surface of the fabric to obtain a surface pattern effect with colour contrast and a soft hand.
Stone washed jeans
Fig: Stone washed jeans
Because the degree of abrasion may vary in different parts of garments, such as the trouser leg, button slays and seaming parts, a number of neutral patterns can be formed. The degree of the wash effect depends on the stone size, stone ratio, liquor ratio, duration of treatment, amount of garments loaded, garment’s grams per square metre, etc. Stone sizes vary from 1 to 7 cm in diameter. Other washes such as sand, micro and microsand wash are refer to the use of very small size pumice stones.
Process flowchart of denim stone washing:

Desizing (10–15 min)


Stone washing

Rinsing (with perborate and optical brightener if necessary)


Stone Washing Process:
  1. Load stones into machine.
  2. Load garments into machine (ratio usually 0.5 - 3.0 part weight stones:1 part weight garments).
  3. Desize with alpha amylase enzyme and detergent. Liquor ratio approximately 5-8:1.
  4. Rinse.
  5. Refill and tumble with stones 30 to 90 minutes, depending upon desired effect. Liquor ratio 5-8:1 at 50-70◦C. Scouring additives can also be used.
  6. Drain. Separate garments from stones (garments can be transferred to another machine).
  7. Rinse.
  8. Apply softener (garments can be transferred to another machine for softening).
  9. Extract and unload.
  10. De-stone and tumble dry.
  11. Press, if required.
Softeners and/or lubricants can be added during steps three and five to reduce creasing potential. Steps 8, 9, and 10 may vary depending upon individual mill arrangement.

Selection of stone:
Stones should be selected for their proper hardness, shape and size for the particular end product. Large, hard stones last longer and may be suited only for heavyweight fabrics. Smaller, softer stones can be used for lightweight fabrics and more delicate items (stone weight/fabric weight = 0.5 to 3/1). It depends on the degree of abrasion needed to achieve the desired result. Stones can be reused until they completely disintegrate or wash down the drain.

However that method proves problematic owing to environmental concerns regarding the use of pumice and the fact that the stone often weakens the fabric too much, causing wear and tear. In the process of stonewashing, freshly dyed jeans are loaded into large washing machines and tumbled with pumice stone or volcanic rock to achieve a soft hand and desirable look. Variations in composition, hardness, size, shape and porosity make these stone multifunctional. The process is expensive and requires a high capital investment. Pumice stone give the additional effect of a faded or worn look as it abrades the surface of the jeans like sandpaper, removing some dye particles from the surface of the yarn.

Stone washing the denim with pumice stones has some disadvantages:
  • Stones could cause wear and tear of the fabric.
  • The quality of the abrasion process is difficult to control and the outcome of a load of jeans is never uniform. A slight percentage always gets ruined by too much abrasion.
  • The process is nonselective.
  • Metal buttons and rivets on the jeans in the washing machines get abraded.
  • It creates the problem of the environmental disposition of waste for the grit produced by the stones.
  • High labour costs become necessary because the pumice stones and the dust particles they produce need to be physically removed from the pockets of the garments and machines by labourers.
  • Denim needs to be washed several times to get rid of the stones completely. The process of stone washing also harms big, expensive laundry machines.
Substitution of pumice stone:
To overcome the shortcomings of pumice stones, synthetic stones were developed. These are made of abrasive materials such as silicate, plastic, rubber and Portland cement. Major problems associated with the use of volcanic-grade pumice stone can be overcome by using these products. Advantages of using these synthetic stones are:
  1. The durability of such a product is much higher and can be used repeatedly from 50 to 300 cycles, depending on the type of synthetic stone.
  2. Reproducibility of washing is manageable.
  3. Because there is much less stone discharge in the process, the process is economical and ecological.
  4. There is less damage to the machine and garments.
Perlite is a form of naturally occurring silicon rock. It has the distinctive property of expanding to 4 to 20 times its initial volume when heated at a particular temperature. This happens because the raw Perlite rock consists of 26% water. When it is heated above 870°C, crude perlite rock becomes swollen and tiny sealed glass bubbles form. Its original black or grey colour changes to greyish white or else white. This heated form of perlite is used for stonewash purposes.
pumice stones
Fig: Pumice stones
It has the same function of stonewashing as stones. Perlite treatment reduces the rate of harm caused to large washing machines by pumice stones and gives denim better suppleness and a softer finish. Many jeans manufacturing companies use Perlite in the place of enzymatic treatment, which reduces the rate at which jeans wear out when used. It gives a uniform worn and old look throughout to the denim, not just the upper part of the garment. There are many grades of Perlite, differing in size. Each is used to giving the right stone wash finish to denim, from the largest to the finest grades; some are very tiny, just like ground earth.

You can also like:
  1. Acid Wash Procedure on Denim Jeans
  2. Super White Wash on Cotton Garments
  3. Stone Wash on Denim Garments
  4. Denim Manufacturing Process from Fiber to Finishing
  5. Different Types of Denim Fabric Used in Apparel Manufacturing
  6. Enzyme Washing Process of Denim Garments