Acid Wash Machine

Effect: Acid wash is done on woven items, light knit and heavy knit to get a worn, frosty effect. The garment gets a lighter color on the inside than on the outside of the garment.

Process: A chemical called Potassium Permanganate (PP) is made into a solution. Pumice stones are put into the solution for some time. After absorbing the solution, the stones are taken out and kept in sunlight to dry. When this stones are used in the washing process it is called acid wash/salt wash.
The same chemical is used for PP spray

Advantages: Only way to get this frosty look.

Disadvantages: The garments you use acid wash on should be dyed with sulpher dye. If they are reactive dyed, it will be difficult to say what color will come out after acid wash.

Garments wash/rinse wash:

Effect: Is used to get a softer hand feel and get rid of chemicals and waste from treatments. Garment wash is the term for flats, and rinse wash the term for denim, but the process is the same.

Process: The garments are washed, similar to normal home laundry, with or without detergent. Sometimes softener is used depending on required hand feel.

Advantages: To clean the garment after the making, and get rid of loose dye stuff etc

Disadvantages: No disadvantages.

Silicon wash:

Effect: To get a slippery, soft and oily hand feel on the garments.

Process: Silicon softener is used in the wash machine.

Advantages: Silicon is a stable softener, which means it will not go away after home laundry wash.

Disadvantages: No disadvantages, but slightly more expensive than garments wash.

Stone wash:

Effect: To get an allover worn look on garments.

Process: Pumice stones are put in the machine together with the garments. When the garments are washed, the stones hit the garment and the abrasion fades the colour. Details like belt loops, seams, edges will get a more worn look than the flat surface of the garments.

Advantages: Will give a good worn look.

Disadvantages: If used alone (not with enzymes) the result can become uneven. This is because the leg and the waist part have different weight, rotates differently in the machine, and will therefore get different abrasion. This will cause more rejections, which is why stonewash is commonly used
together with enzyme wash. If stonewash is done too heavily, the fabric can become too weak and break,
especially on belt loops, bottom hems etc, and the garments will be rejected.

Enzyme wash:

Effect: To get a worn look on garments. The worn effect is the same as stone wash

Process: Instead of pumice stones, which you use in stone wash, enzymes (chemicals) are used to get the faded out look.

Advantages: There is less chance of rejection than on stone wash
(no broken edges etc.)

Disadvantages: Compared to stone wash, the abrasion are less.

Enzymes

There are different types of enzymes that washing plants use for different purposes:
1. Amylase Enzyme
2. Laccase Enzyme
3. Cellulose Enzymes

Amylase Enzyme (de-sizing)

Effect: In the weaving sizing materials (starch) is used to make the yarn stiffer, so the weaving is made easy. If this is not removed the following wash treatments will not have a good result. Amylase enzyme is used to remove this starch, and the process is called “de-sizing”.

Process: The amylase is added in the washing machine.

Advantages: The other wash treatments that is made on the garment (e.g. enzyme wash) will be efficient, and get more even result after de-sizing is done.

Disadvantages: No disadvantages.

Acid Celluloses Enzyme

Effect: To get a worn effect all over the garments, at edges, belt loops, seams etc.

Process: The enzyme is used in the wash machine.

Advantages: It is a very aggressive enzyme, so the effect can be achieved quickly.

Disadvantages: Back staining/re-deposition of dyestuff is much higher, which means that pocket linings etc can become discoloured.

Laccase Enzyme

Effect: Is used to get outstanding contrasted look on denim fabric. Can also be used on non denim, but it is not as common.

Process: The enzyme is used in the wash machine

Advantages: The indigo is reduced faster than with other enzymes, so abrasion and washed out look will appear fast with less time in wash.

It works almost like bleach (see B7), but will give more contrast to the fabric so it will not look as flat as bleach. It will however not give as light result as bleach. Important advantage is also that it is much less damaging for the environment than bleach.
Re-deposition of dye stuff is less, so you will get less back staining.

Disadvantages: More expensive than other enzymes.

Bleach wash (used only on denim):

Effect: To get a faded out, lighter shade on denim.

Process: Calcium hypo chloride, a bleaching agent, is added in the wash.

Advantages: It is the only way to get the denim much lighter. If you want a less bleach look, laccase

Disadvantages: The fabrics tensile strength will be reduced. Bleach is not environmental friendly.

Combination of wet processes

The wet possesses are commonly used in combination with each other.

For example:

Sand + Silicon: Is used to get a slight washed out look, a peachy feeling, and a slippery hand feel.

Enzyme + Silicon or Stone + Enzyme + Silicon:
Is used to get a washed out look, and a slippery hand feel.
Both options give similar look, and factory decide from case to case what is better.

Enzyme + Bleach or Stone + Enzyme + Bleach:
Is used to get wash abrasion and a lighter shade on denim.
Both options give similar look, and factory decide from case to case what is better.

Conclusion

Acid Wash, Stone Wash, Silicon Wash and Enzyme Wash is applied in washing factory