What is acid wash? Acid wash process on denim jeans?

Acid wash jeans
What is acid wash

Acid wash is the technique used to change the look, feel, comfort ability and fashion of a garment. This is done on garments made from heavy fabrics like denim and jeans. Today fashion is incomplete without denim. Various washing processes are used to change the look of denim or jeans. Among the various washing processes for denim, acid washing is the most popular.

Acid wash on denim jeans has become popular because of its remarkable contrast and attractive color appearance. Acid washing can be done on blue- and sulfur-based fabric clothing. An acid wash is a chemical washing process on denim that strips away the top layer of color and creates a white surface while the color shows through on the layers below the material, giving it a faded appearance.

Acid wash jeans

Acid wash jeans

It is also a type of stone washing, which is done with pumice stone. Due to severe abrasive action, surface fiber damage occurs.Acid was first introduced in the 1980s as an innovative finish on denim garments. This washing is done by soaking the stone in bleach, followed by neutralization.

An acid wash finish treatment creates significant contrast in the color of the denim material. This can be done on indigo and sulfur base fabric garments. Some have tried using a method such as stone washing, yet the discoloration did not occur dramatically or throughout the material.

This was done by soaking the stone in bleach and neutralizing it creating an acid wash effect. But how consistent and smooth the effect this process can have on denim is yet to be found.

Although this process can be done using either mild bleach, chlorine, potassium permanganate etc. The most popular is PP bleach and acid wash will give the best results. The process is very easy to do, but follow all the parameters in the right way to get accurate and repeatable results. Garment load size, machine drum diameter, wet stone/towel and skilled operator.

The acid washing process involved soaking pumice in industrial strength chlorine. However, it was discovered that potassium permanganate is more controllable than and just as powerful as an oxidizer. They simply marinate pumice stone in it and then vacuum pack the stone to the required moisture level. Acid washing was a chemical process on denim that stripped the top layer of color to a white surface with navy blue undertones remaining on the jeans.

Pumice stones are first soaked in a solution of a strong oxidizing agent (either sodium hypochlorite (5-10%) or potassium permanganate (3-6%)) and then applied to the garment by dry tumbling. This results in a locally washed effect with clean blue/white contrast. This technique is called acid washing. It is also called ‘snow washing’ or ‘ice washing’.

The acid washing effect gives sharp contrast to the blue jeans. Acid wash denim does not use actual acid in the washing process. Instead the process uses pumice stones soaked in bleach to change color in a nonuniform manner. The result is often a spotted yellowish pattern.

Acid washing is also known as stone washing, which is done with pumice stone. For acid washing, the base color of the garment is removed by spraying acid on specific areas. Washing is performed in two steps: in the first step, the clothes are washed without water and in the second step, with water.

Process Flow Chart of Acid Wash:

Garments loading in machine


Extracting the garments


Soaking of pumice stone

Damp pumice stone

Neutralization the garments


Extracting the garments


Acid Wash Process

The acid wash process involves the use of a few materials and steps to achieve the desired effect on denim jeans.

Acid wash materials required
  • Hydrochloric acid
  • Bleach
  • Water
  • Denim jeans
  • Plastic bucket or tub
  • Rubber gloves
  • Eye protection
The Acid Washing Process: Step-by-Step
  1. Dilute the hydrochloric acid solution according to the manufacturer’s instructions.
  2. Wet the concrete surface thoroughly with water.
  3. Apply the acid solution to the concrete using a sprayer or watering can.
  4. Use a stiff bristle brush to scrub the surface of the concrete, focusing on any areas with stains or discoloration.
  5. Allow the acid solution to sit on the surface for 10-15 minutes, or as recommended by the manufacturer.
  6. Rinse the surface thoroughly with water, using a pressure washer if necessary.
  7. Apply a baking soda solution to neutralize the acid, using a sprayer or watering can.
  8. Rinse the surface again with water, and allow it to dry completely before applying any sealers or coatings.

Effects of Acid Wash on denim jeans

The acid wash process has several effects on denim jeans:

Fading and Distressing

The acid solution and bleach work together to remove the top layer of indigo dye on the denim jeans, resulting in a faded and distressed appearance. The degree of fading and distressing can vary depending on the amount of acid used in the wash.

Softening of the Fabric

The acid and bleach solution also breaks down the fibers in the denim, making the fabric softer and more comfortable to wear.


Due to the harsh chemical treatment involved in acid wash, denim jeans may experience some shrinkage during the washing process. It is important to consider this when choosing the size of your acid washed jeans.