Tag Archives: Yarn Dyeing

Functions Of Chemical Auxiliaries Used In Wet Processing | List Of Chemical Auxiliaries

We know that dyes and chemicals are the main factor for producing color in yarn of fabric. Different types of chemicals are used during dyeing. In different stages of dyeing processing, various chemicals are used. Every chemical have their own characteristics and they are used in different stages of wet processing.

List of Chemical auxiliaries used in wet processing unit and their function is given bellow:

  1. Acid: Acid is used to control PH. Acid decrease the pH of the solution. If PH 1-7 then it is called Acidic solution.
  2. Basic: Basic is used for increase the PH of the solution. PH range of basic is 7-14. This also used as scouring agent.
  3. Peroxide Killer: This chemical is used to kill per oxide which is remaining in the material. Peroxide is harmful for the material. A test is carried out to measure the amount of peroxide present in the solution.
  4. Bleaching Agent: Bleaching is carried out before dyeing or printing operation. Better absorption of dyes depends on better bleaching. Absorbency test is carried out to test the bleaching performance. Absorbency time should lie under 5 second. It is used for removing natural color from the grey yarn or fabric.
  5. Salt/Electrolyte: Salt is used as electrolyte. Salt increase the exhaustion rate of the dyeing process. Different types of salt are used for different shade. The amount of salt used depends on the shade % of the material.
  6. Scouring Agent: Scouring agent is used to remove fat, waxes, fragments of cotton etc.
  7. Antifoaming Agent: Foam is formed during bleaching and dyeing process. Anti foaming agent is used to resist foam formation. If foam formed it reduces the dyeing uptake %.
  8. Sequestering Agent: This agent is used to remove hardness of water.
  9. Dispersing Agent: This agent is used for disperse dyes. We know, disperse dye is insoluble in water and dye present in disperse form. By applying this agent dye molecule breaks and become soluble in the solution.
  10. Neutralization Agent: This agent is used to neutral the PH of the solution.
  11. Wash/Soaping Agent: Soaping agent is used for washing. It needs to wash dyed material to remove unfix dye from the material. Dark material needs double wash. But light shade materials needs single wash, sometimes no wash is carried out for light shade. It also increases the reflecting properties.
  12. Softening Agent: This agent is used to increase softness of the material. This agent used as finishing material.
  13. Fixing Agent: This agent is used for fixing of dyestuff and also remove the unfix dye.
  14. Brightening Agent: This agent is used to increase the brightness of the material. This agent increases the reflecting property of the material. Standard reflecting value is 85%. But sometimes it is possible to increase it up to 95%. But it is risk because it needs high kier boiler temperature, which reduces the strength of material.

So, we should use the chemical auxiliaries according to their scope of use.

What is A Lab Dip Development | Objectives And Basic Sequence Of Lad Dip Work

Lab Dip Development means the sample which is dyed according to buyer’s requirements (similar shade and so on). Depending on lab dip development sample dyeing and bulk production dyeing planning is done.

 Object of Lab Dip: The main objectives in lab dip are as follows:

  • To calculate the recipe for sample dyeing.
  • To compare dyed sample with swatch by light Box or Spectrophotometer.
  • To calculate revise recipe for sample dyeing.
  • Finally approved Lab Dip (Grade: A, B, C & D)

Process Sequence of Lab Work: Lab work plays an important role in dyeing process. Bulk dyeing process completely depends on the lab dip development work. Lab work is completely managed as the following sequence.

 

Lab Dip Requisition from buyer

Entry in the computer

First recipe is given by swatch/pantone number

First correction

Second correction

Grading of sample (A, B, C, D)

Yarn and knit sample send to buyer

Approved by buyer

Order for bulk production

Production card with approved sample and recipe send to production section.

 

Anyhow, lab work is important because it related with the buyers satisfaction. If the lab dip is developed as the given swatch or pantone number which is given by the buyer then it will get bulk production order, which is the main goal of a company.

So, dyeing lab management and its lab dip work is important for a dyeing industry.

 

Process Flow Chart Of Lab Dip Development In A Dyeing Lab | Shade Matching Procedure

Dyeing is performed in the dyeing floor but before starting bulk production a lots of work is done in the dyeing laboratory. In the lab, lab dip or sample is developed by the textile engineer or technician. In lab, lab dip is matched with the sample given by the buyer. Then lab dip is send to the buyer for his approval. In lab, full work is done in sequence.

In a dyeing lab, lab dip is developed like the following sequence:

Receiving standard swatch

First recipe take from Spectrophotometer or manually

Dispersion by autodoser

Trial dyeing of first recipe

Unload

Normal wash

Hot wash with detergent

Finishing

Hydro

Drying

Compare with standard swatch

If not ok

First correction takes from Spectrophotometer or manually

Dispersion by autodoser

Trial dyeing of first recipe

Unload

Normal wash

Hot wash with detergent

Finishing

Hydro

Drying

Compare with standard swatch

If not ok

Second correction takes from Spectrophotometer or manually

Dispersion by auto doser

Trial dyeing of first recipe

Unload

Normal wash

Hot wash with detergent

Finishing

Hydro

Drying

Compare with standard swatch

If ok

Send for buyer’s approval

The flow chart which I have given in above is all most same in the entire dyeing laboratory. But this sequence could be changed depending on the engineers own procedure. This procedure is applicable for yarn or fabric dyeing.

In dyeing lab, the textile engineer should have deep knowledge about the shade matching.