Denim Wash Types and Techniques: Stone, Enzyme, Ozone, Laser

Denim wash types: dry and wet processes

Turkish names are in italics for reading supplier quotes; "commercial source" marks statements from the information page of thread maker Coats.

Sandblasting is not counted among these processes: it is banned on jeans in Turkey and has its own section.

Stone wash vs enzyme wash vs rinse: the classic wet processes

Stone wash (with pumice)

In stone washing, garments tumble with pumice stones in a washing machine. The stones abrade the outer layer of the dyed yarn, the undyed inner fiber shows, the color lightens and the fabric softens (Gündüz, 2023, p. 7; Coats). Coats counts variants made with very small stones (sand wash, micro wash) as subtypes; these are washes with small stones, not sandblasting. In its comparison with enzyme washing, Coats says pumice can abrade the machine and garments and that used stones need disposal (commercial source).

Enzyme wash

Enzyme washing uses cellulase to remove dye, alone or with pumice, and gives denim an aged look (Gündüz, 2023, p. 7). Coats writes that cellulase acts only on cellulose, so sizing must be removed first; that neutral cellulase hurts breaking strength less; that acid cellulase can increase backstaining (indigo sticking back onto the fabric); and that enzyme washing without stones removes stone waste and machine wear (commercial source).

Rinse

Rinse is simpler than the other washes: the garment is washed in cold or warm water for a short or medium time, and because the conditions are mild its physical properties change little (Oğulata and Nergis, 2016, cited in Gündüz, 2023, pp. 7–8). According to Coats, the aim is to keep the fabric as dark as possible, and the drawback is very poor rubbing fastness (commercial source).

Bleaching and spray: lightening color with chemicals

Bleaching lightens color by breaking down indigo in a chemical reaction, using oxidizing or reducing chemicals (Gündüz, 2023, p. 7). More chemical or a longer time gives a more worn look but lowers wear performance (Gündüz, 2023, p. 7). According to Coats, hypochlorite bleaching damages the fiber and produces dirty wastewater, and residual chlorine must be removed after every chlorine bleach (commercial source).

In acid wash, pumice stones soaked beforehand in a hypochlorite or permanganate solution tumble with the garments in a dry drum, giving localized bleaching and a sharp blue-and-white contrast. Coats adds that this hypochlorite process can cause serious strength loss at seams and pockets, breakage and small holes (commercial source).

Some brand programs restrict these processes. Under Material Health, the Ellen MacArthur Foundation's September 9, 2021 Jeans Redesign page says: "Stone finishing, potassium permanganate (PP), and sandblasting are prohibited." This is a condition for participating brands, not a law, and the page does not define "stone finishing"; confirm what is meant against your own specification.

Dry processes and laser finishing

Whiskering, distressing and sanding

These processes give the garment a used look mechanically (Palabıyık et al., 2024). The same source lists kılçık among the dry processes without explaining it; ask the supplier what effect is meant.

Laser finishing

Laser is a contact-free method that gives denim patterns, fading and engraving effects. Citing case studies of two Vietnamese denim manufacturers, RMIT Vietnam's January 11, 2023 release says digital laser saved 97% of water, 70–90% of energy and 60–70% of chemical cost, and cut processing time from 30–45 minutes with the conventional method to two minutes. The release adds that few Vietnamese denim companies use laser and ozone, because of high initial investment and skill requirements. These percentages come from two factories and cannot be carried over to another plant, country or product (underlying article: Nayak et al., 2022). Machine suppliers are in the dyeing and finishing machines category.

Ozone wash: bleaching denim without hypochlorite or permanganate

Here, ozone wash means bleaching a denim garment with ozone gas. Ozone is a strong oxidizer that breaks down the structure of indigo, so a garment can be lightened without pumice stones, potassium permanganate or sodium hypochlorite (Palabıyık et al., 2024, p. 882). According to RMIT, ozone can remove indigo from the surface without a chemical or water bath; no rinsing is needed after dry ozonation, and after wet ozonation one or two washes are enough to remove residual ozone.

Palabıyık et al. bleached a denim garment of 78% cotton and 22% hemp at ozone capacities of 25, 50 and 75 g/Nm³ for 5, 10 and 15 minutes. As dose and time rose, color difference (ΔE) and yellowness rose; against the raw fabric, color difference ranged from about 14 to 44. The authors attribute the yellowing to isatin sulfonic acid formed as ozone breaks down indigo; an after-wash with detergent and softener was applied to remove it. Tear strength fell as dose and time rose. It is a single laboratory study, not a general recipe.

Sandblasting jeans is banned in Turkey; stone wash is a separate process

Sandblasting, blasting sand onto jeans and denim fabric to age them (kumlama in Turkish), is banned in Turkey. The basis is circular no. 2009/24 of the Turkish Ministry of Health, General Directorate of Primary Health Care Services (dated March 27, 2009 on the document): no material containing sand (silica dust) or silica crystals may be used in the spraying process. The ministry gives two reasons: silicosis has become more frequent among sandblasting workers, and adequate protection for workers and the environment in these workshops does not seem possible.

Legally this is a ministry circular, not a law or regulation. As of this article's date (October 16, 2026), the information rests on the circular's own text; check the ministry for later changes, and ask an occupational health and safety specialist about practice at the plant. Stone washing with pumice in a machine is a wet process that the circular does not mention. The Turkish word taşlama can be used for either process, so write the full process name on the order and in the specification.

How washing affects strength, size and handle

Sources point in different directions: the result depends on the fabric, the process and the property measured, and a single study cannot be generalized. Tear strength and breaking strength are not the same test. Our recommendation at Tekstil Rehberi is to have strength measured before and after washing, on your own fabric and with your own recipe.

Do jeans shrink after washing?

They can. Kan and Yuen (2009) studied repeated washing of elastane-containing denim: shrinkage was clear up to the fifth wash, then dimensions stabilized; denim with a higher elastane share showed more shrinkage and more change in mass and thickness (cited in Gündüz, 2023, pp. 8–9). This is a single study, so ask for a repeated-wash trial on your own fabric. ISO 5077 sets how dimensional change is calculated; the wash and dry program is chosen from ISO 6330. To reach the finished size after washing, work out the cutting allowance with the shrinkage calculator.

Water, energy and chemical load: what the sources report

Figures are given only as far as the source gives them, and statements from the commercial source are labeled.

To judge chemical load, ask the plant which chemical suppliers it uses and how it treats wastewater. The ZDHC MRSL lists substances that must not be intentionally used in chemical formulations or must not exceed limits; conformance is shown at chemical-product level (ZDHC). One certification rule matters: under section 5.10 of OEKO-TEX STANDARD 100 (edition 01.2026), a certified product automatically loses its certified status and the right to use the STANDARD 100 label once it undergoes a professional physical or chemical treatment, including washing and chemical cleaning. This holds as of the article's date; ask your certification body whether the washing falls within your certificate's scope. See the textile certifications guide for more.

What to give and ask a denim washing plant

The wash result depends on how clear the order is. Give the plant these in writing and ask about each:

1. Approved physical sample. Tie the agreement to a reference sample signed by both sides, not a verbal description, and use a trial lot to check that the plant can repeat the result in bulk.
2. Recipe responsibility. A chemical's result at a given temperature and time is hard to predict, so recipes are developed by trial (Gündüz, 2023, pp. 6–7). Write down who writes the recipe and how it stays confidential.
3. Fabric and fiber information. Give the fiber blend, including the elastane share, and any pre-treatment such as shrinkage control; the elastane share affects shrinkage (Kan and Yuen).
4. Size and fastness tolerance. Put the post-wash size tolerance in the tech pack (ISO 5077) and tie indigo transfer to rubbing fastness (ISO 105-X12).
5. Damage and wastage liability. Write down who bears pieces damaged in washing, re-washing, and the accepted wastage rate.
6. Lead time. It depends on the number of wash steps, effects that need handwork, the plant's daily washing and drying capacity, and the trials needed to match the approved sample. If laser or ozone is done at another plant, add transport time and liability for damage in transit.
7. Documents. Check which plant a chemical-management document (for example OEKO-TEX STeP, or conformance of the chemicals used with the ZDHC MRSL) covers, and its validity date.
8. No sandblasting. Ask for written confirmation that sandblasting, which is banned, is not carried out at the plant.

You can find washing plants in the garment and denim washing category and jeans manufacturers in the denim apparel category.