Outside of the normal characteristics like some chemical and physical properties are being looked at pumice that is used at this sector. Pumice used in the textile sector is mostly intended to bleaching and softening of cotton clothing such as jeans, blue jeans. If only softening the fabric is requested water + pumice Stone is used and the process is called (stone wash). If bleaching and also softening of fabric is requested, water and chemical-impregnated pumice is used. This process is called the snow-wash. Apart from these two processes only blasting the areas requested (sand blasting) process.

Stone Wash

Process of water and pumice stone were treated with the erosion in the color of the clothing made of denim fabric in rotary drum dyeing and washing machines. It is the most conventional method of etching that gives an extremely realistic aged form to the garment. During treatment with a pumice stone in a washing machine, the product’s inner unpainted fibers comes out by fraying indigo-painted outer surface. After a short period of time which is 45-60 minutes treatment with pumice stone, clothes looks like used for many years. But the time will vary between 10 min. to 3 hours depending on desired colour opening and the amount of color effect on the product. Using amount of stone for the process of tumbled is determined by -the desired effect- usage (0,5 to 4 times the weight of product). However, generally 1,5 to 2 times the weight of the stone used in the product.

Pumice stone disintegrates and sand occurs during usage so that cleaning of that is a problem. As well as during the stone-wash process problems also can be seen such as excessive wear on the machine and the product, difficulty of color control, difficulty of the purification of stone remnants, duct obstruction and so on. In order to overcome these problems, the during stone-wash process, plastic balls can be used as an alternative to the pumice stones.

However, at stone washing process using plastic balls instead of stone pumice is generally not preferred because of the following drawbacks; because of having larger sizes than real pumice stones they can’t enter inside the products during the washing process so this makes it impossible to capture the washing color effect with plastic balls than pumice stone. During washing processes they cause a very high noise which makes working conditions difficult. Because of being very expensive materials than the pumice stones they raises the costs of the process. Unlike pumice stones they have no fragmentation characteristics with water, waste water can lead to blockages in systems.

The use of plastic balls are not preferred due to the above drawbacks. The most attential issue is to ensure there are no remains of stone products in the products pockets (especially from children's clothes) after the washing process. The most noticeable. The most important security measures taken for this purpose is sewing all the pockets of the products before the washing process and controling all products without exception after the washing process.

Snow Washing

Pumice stones can also used at the snow process of dismantled sizing denim product’s washing process with impregnated pumice stone bleaching agents (eg: potassium permanganate) in dry process rotary drum washing machines. The snow washing process in dry process is completed with neutralization process (with sodyummetabisülfit).

In this process which is named "Snow washing" potasıumpermanganat solution is generally used as a bleaching agent but also sodyumhipokloritten can be helpful. However, sodyumhipoklorit that is harmful to human health is not preferred today because of revealing AOX (adsorbed organic halogen compounds).

Enzymatic Stone Washing Process

The other variation of stone washing of denim fabrics is combination of enzymatic washing and stone washing. This method started to be implemented in 1986 by production of enzymes that is called "Cellulase".In this new method that is adopted by many big denim washing enterprise, the cellulase enzyme which abrades cellulose(cotton) fibers is also used with pumice stone. In this method, due to the reduced amount of used stone, the resulting problems due to excessive use of stone are eliminated.

Obviously, the stones are not abrade only clothes and also abrade machinery and equipment. Changing drums in drum washing machines or drum driers are expensive. Cellulase enzyme used at abrasion of cotton fibers is a special type of enzyme produced by microorganisms. Cellulase enzymes show an enzymatic degradation on cellulose by effecting 1-4 beta-glucoside bond. Under certain circumstances this situation leads to a decrease in molecular weight. Because of this effect loss of a small amount weight and strength occurs. Weight loss is a direct result of separating surface fibers. The main controlling factors of controlling effects of activity cellulase enzymes are these:

pH
Temperature
Period
Concentration
Mechanical impact

Cellulase enzymes cellulase enzymes stone cleaning can be divided in two groups:

Acid Cellulase
Neutral Cellulase

Stone Wash with Acid Cellulase

The optimum operating range of pH is among 4 to 5.5 at the stone washing with acid cellulase enzymes. These enzyme’s activity to cellulose is higher. This pH value can be achieved by using acetic acid alone or using sodyumhidroksit-acetic acid as a buffer system.

The activity significantly reduced above 60 ° C. The best operating range is the 50-60 ° C. A longer washing process can be required at lower temperatures. In the implementation of acid cellulase enzyme and stone washing combination, the working conditions and processing steps can be:

Stone Wash with Neutral Cellulase

The maximum color change occurs around pH = 6,0 at neutral cellulase enzyme. However, between pH 7 to 7,5 color change effect on this enzyme over % 90. Even if it is possible to work them at 40-45 ° C energy savings can be achieved. The working conditions at stone washing with neutral enzymes could be the following:

Because of stone washing enzymes hydrolysis the cellulose enzyme must remove over the fabric or deactivation must be done after the process. This may be done with the soda-soap wash, degradation of the enzyme can be achieved by increasing the temperature or it can be made by drying. Cellulase enzymes are completely bioparting products. There is no harm in terms of human and environmental health.

Pumice stone’s physical and chemical (Na2O - K2O) features are perfectly suited for grinding of finished products in the textile industry. By the development of washing techniques, it has also be started to use pumice stone for washing lighter than heavier weight fabrics. In addition, a larger calibrated pumice stone has also been begun to be used in a new generation of washing machines. The pumice stone used in this sector is the one acidic and it’s color is white, does not create stains on the product and does not require cleaning. This does not get an additional increase on the cost of the textile product. However, pumice that will be used need to keep rounding process so-called tumbling and carefully separated from all other foreign substances. In addition, must be calibrated in different sizes because of differences of washed fabrics and wash machines.

The pumice used in the textile sector must have the characteristics that is called textile quality. The demanded features additional to the the regular features of pumice used in the textile sector are:

Pumice must have medium hardness, be crushed without breaking, should be free of foreign materials (iron oxide, sodium oxide and potassium oxide in the amount of fabric must not be dying), must be dry-porous and rounded, quality of stone used must not be changed, must be homogeneous, usually size must be 30x40x50 mm, its color must be white, must be swim and not to be broken in the water for a certain time, the amount  of absorbtion water must be ideal for textile quality. For the washing process 0,5 to 1 kg. pumice must be consumed for a piece of blue jeans from.

Quality Norms of Textile Pumice

A published national or international standard for textile pumice is not available. However, there are user preferences and demands of domestic and abroad companies, the intended physical and chemical properties of pumice stone to use as appropriate is located at the level in question. General quality demands of domestic and foreign firms in textile pumice are given below such as"Physical Properties" and "Chemical Properties" sub-headings.

                                    The use of pumice in textile industry

1. The pumice which’s physical properties are at textile quality must have general physical characteristics that is stated at Table 2.1. The pumice aggregates at textile quality as a finished product’s granulometric must comply with the following size ranges:

10 to 20 mm. (Combed cotton, Fine Denims)
15 to 25 mm. (Combed cotton, Fine Denims)
20 to 30 mm. (Denim shirts, Combed cotton)
20 to 40 mm. (Denim shirts, T-Shirts)
30 to 50 mm. (Normal Denims)
30 to 70 mm. (Normal Denims)
50 to 70 mm. (Normal Denims)

1. Chemical Properties of Textile pumice in Table 2.2. 'Demonstrate compliance with the specified chemical properties.

Table 2.1. Physical properties of textile-quality pumice

* It is the moisture limit of the cast product, also the production must be 100% dry which is packed packed in bags and big-bags.

Note: The pumice stone used for grinding and softening should not contain the free  (water soluble) Fe + +, Ca + +, Mg + + and other heavy metal ions that may affect the enzyme.