What is Check and Control Points in Dyeing?
Dyeing is the process of imparting colors to a textile material like fibers, yarns, and fabrics. It is one of the complex processes for textile engineers. During dyeing, textile engineer should give deep concern on the some points. He should give proper instruction to his supervisor or operator to do all the work as per schedule. If any faults occur during dyeing process then it will impact on overall process.
It is essential to have clarity on the points to be controlled to achieve the targets and those to be checked to ensure the process in control. These points need to be reviewed from time to time and modified to suit the requirements of individual companies and their targets. Each dyeing mill should prepare its own ‘Check Points and Control Points’ and display them in the work area so that the supervisors refer and follow. Following checking points must maintain during dyeing process.
Important Checking Points of Dyeing:
| Checking instrument/type | Points | Requirements |
| pH: measured by digital pH meter and pH measurement strip/paper | 1. Enzyme/bio-polishing 2. Cotton leveling 3. Salt in side tank 4. Dye bath 5. Fixing 6. Softening 7. Unload | 4. 5 6. 5 7. 0 As per alkali 5. 5 5. 5 6-6.5 |
| Residual peroxide: by peroxide measurement strip | After per oxide killer | 0-10 mg/v |
| Hardness: by hardness measurement strip and titration process | 1. Line water 2. Dye bath 3. Salt/soda | Less than 30 ppm |
| Specific gravity: by hydro meter | 1. Salt in side tank 2. Dye bath | As per SG graph |
| Weighting of colors and chemicals: by digital weighing balance | As per requirements | |
| Sample check | 1. Before load 2. Bleaching 3. Enzyme 4. Dyeing shade check 5. Hot wash 6. Fixing 7. Unload | |
| Information | 1. Batch parameters in dye line 2. Operator name 3. Load/unload date/time/shift, total duration 4. Information’s attached in unload folder | |
| Before start dyeing | 1. Condition of machine 2. Pressure of air, steam, water line etc 3. Machine ok from maintenance 4. Batch ready for dyeing 5. Lap dip, color, batch information etc ready for dyeing. | |
| During dyeing | 1. Programme and process for that particular batch and color. 2. Liquor ratio, chemical and color amount, time and temperature of specific process steps 3. Cycle time, fabric absorbency, bleaching whiteness, fabric running inside the machine 4. Color and chemical dissolving, transferring and dosing. filtration of color, checking monitor information during processing whatever necessary to maintain 5. Responsible operators, helping must be present in front of machine during processing specially for dyeing. | |
Control Points in Dyeing Process:
a) Selection of suitable dyeing machine for the material to be processed.
b) Deciding and selection of process parameters, namely:
- Process parameters
- Speed
- Running time for each operation
- Temperature
- Pressure
- Dye recipe
- Liquor ratio
- Washing and fixing sequences
c) Deciding acceptance criteria for shade matching and color fixation.
d) Deciding on chemicals and their quality to be procured.
e) Employing trained and qualified employees.
f) Evolving production norms.
g) Evolving norms for consumption of chemicals, water and steam.
Editor of Fashion2Apparel. She is a fashion designer and ex-lecturer in Fashion Designing. She wants to spread fashion knowledge throughout the world.
