Md. Imran Hossain
Introduction
Right First Time (RFT) is very popular term in the textile industry, particularly in dyeing processes. It quantifies the accuracy and consistency between lab dips and bulk production. RFT means achieving the targeted shade correctly on the first attempt, eliminating the need for rework or adjustments with additional dyes or chemicals. A higher RFT% signifies better control over the dyeing process, reduced dyeing time, reduced rework and improved overall efficiency. However, achieving high RFT% in cotton fabric dyeing with reactive dyes can be challenging due to various factors.
This study delves into the key factors that contribute to lower RFT% in the lab-to-bulk dyeing of cotton fabrics with reactive dyes. By understanding these factors, we can identify potential areas for improvement and implement strategies & SOP to minimize the adjustments and increase RFT%.
This study aims to:
- Identify the primary factors influencing RFT% in cotton dyeing.
- Analyze the impact of these factors on color consistency and production efficiency.
Ways to mitigate these factors on color consistency and production.

Factors Influencing RFT%
Right-First-Time (RFT) dyeing is a crucial goal in textile manufacturing, aiming to achieve the desired shade in the first attempt. While lab-scale dyeing provides a controlled environment for recipe development, scaling up to bulk production often presents challenges leading to shade variations. Several factors can influence the lab-to-bulk RFT% cotton dyeing with reactive dyes:
Fabric Related Factors
- Fabric Structure: If a lab dip is prepared using a specific fabric structure (like S/J) and the same recipe is used to dye a different fabric structure (like Terry) in bulk production, the dye uptake rate and fixation may vary. This is because different fabric structures have varying fiber accessibility, porosity, and surface area, which can influence the dye absorption and retention properties.
- Yarn Lot: If the yarn lot of lab dip & bulk fabric is different, the scouring quality, dye penetration, dye fixation and color uniformity can be influenced by this variation. Differences in fiber quality can affect dye affinity, while variations in yarn twist can influence dye migration and levelness.
Dyes & Chemicals Related Factors
- Dyes Compatibility: As the recipes are made by tri-combination of dyes (Generally Yellow, Red & Blue), if all types of dyes do not show the same dye exhaustion & fixation rate, the depth of shade & tonal variation will occur as the mixing & dyeing of dyes in bulk production starts at 600C and in laboratory dyeing starts at 30-400C. As the temperature increases, the substantivity of reactive dyes for the fabric decreases, while the rate of dye migration increases. This means that higher temperatures may lead to quicker dye uptake, but they can also result in shade variation.
- Dyes & Chemicals Strength: The strength of dyes & chemicals used in dyeing needs to be checked regularly. Because the strength of dyes/chemicals stocked long ago starts decreasing day by day, so that there are various problems occur with dye dissolving and dye fixation.
- Dyehouse Water Quality: Dyehouse water quality, water hardness & PH range must be maintained properly, otherwise the dyes and soaping agents may react with the water hardness to precipitate and K/S value may also decrease.
Dyeing Process Parameters
- Dye Dissolve Temperature: Dissolving dyes at their optimal temperature ensures complete dissolution and uniform dispersion, preventing dye aggregation and degradation. The dyes should be dissolved on the side tank of the dyeing machine at 40-600C temperature. As most of our reactive dyes are medium brand dyes and the manufacturer’s guideline is given within this range.
- Control Dyeing & Run Time Management: In bulk production, a large quantity fabric is dyed. So, the rope length per nozzle, fabric cycle time, proper run time management, proper steam generation and maintaining dye bath PH should be monitored and controlled strictly otherwise uneven dyeing and shade variations may occur.
- Liquor Ratio: In laboratory 1:6 to 1:10 liquor ratio is used incase of reactive dyeing but in bulk production 1:5 to 1:6 liquor ratio is used, this may lead to shade difference. A lower liquor ratio means higher concentration dyes become aggregate and unable to diffuse into the fiber and a higher liquor ratio means a lower concentration of dye molecule in the bath, there is a chance of hydrolysis and lack of absorption due to the higher distance of each dye molecule. Maintaining consistent liquor ratios between lab and bulk is crucial.
Dyeing Machinery & Equipment
- Machine Calibration: Inaccurate calibration of dyeing machines can lead to inconsistencies in temperature, time, liquor ratio, nozzle adjustment, pump adjustment, reel speed, and tis may lead to differences in shade.
- Machine Condition: Poorly maintained or unclean dyeing machines can introduce contaminants and affect dye performance.
- Automation: Automation improves Lab to Bulk dyeing RFT% by accurate dosing, temperature, and time control, real-time monitoring and historical data analysis, minimized manual interventions and standardized procedures. These factors lead to higher RFT% and better shade matching. Automatic Pipetting system in dyeing laboratory minimizes the risk of human error, also contribute to improved accuracy, efficiency, safety, and cost-effectiveness in dyeing laboratories, ultimately leading to better quality control and increased productivity.
Human Factors
- Operator Skill & Experience: Experienced and well trained operator can minimize errors, they can operate machine properly, they can consistently follow dyeing procedures, ensuring that all parameters, such as temperature, time, and chemical dosages, also can identify deviations from normal process conditions and take corrective actions to prevent shade variations quickly.
- Communication: Skilled operators can effectively communicate with supervisors, technicians, production officer and quality control personnel to ensure seamless process coordination and to avoid misunderstandings.
Ways to Achieve Good RFT%
Implement Chemical Management System: Chemical management is essential in dyeing industry for achieving accurate dyeing results. Shade mismatches often arise from issues such as untested chemicals, improper dispensing, dye strength variation, not following Manufacturing Restricted Substances List (MRSL) and improper chemical selection. By following MRSL, dye houses can significantly mitigate these challenges because its goal is to manage and limit harmful substances throughout the textile production process. Currently, the Zero Discharge of Hazardous Chemicals Foundation is assisting factories in implementing proper chemical management practices.
Advanced Laboratory Setup: Modern & well-organized laboratory with properly trained staff plays a crucial role in the successful implementation of RFT dyeing. This includes tasks like evaluating dyes, preparing a database for computer color matching, making accurate stock solutions and automatic pipetting system. Each of these is essential for achieving RFT dyeing results.
Develop SOP: To achieve the desired RFT% in dyeing, all processes must be standardized at every stage—before, during and after dyeing. This standardization helps bring any non-standard conditions within acceptable tolerance limits, ensuring consistency and quality. Each action in the dye-house should have an SOP, covering processes such as:
- Lab-to-bulk RFT
- Bulk-to-bulk consistency
- Dosing dyes & chemicals accurately
- Cutting samples from a running machine
Following SOPs ensures smoother operations, better results, and consistent quality across all dyeing batches.
Advanced Machineries: Technological advancement is a powerful way to enhance RFT%, but only when it’s suited to the specific process. Differences between machines can increase the risk of non-RFT dyeing. Expecting high efficiency from an under-capacity & manual or semi-automatic machine is unrealistic. Selecting the automated dyeing machine and calibrating it regularly are crucial steps to achieve RFT dyeing.
Implement Six-Sigma Practices: Six Sigma DMAIC (Define-Measure-Analyze-Improve-Control) methodology is a tool for enhancing the fabric dyeing process. By using this approach in a dye-house, it’s possible to improve RFT results.
Data Bank: Having a well-organized data bank is valuable for efficiency and quality for any production-based industry. It helps shorten dyeing times by providing accurate recipes from the start, which also helps maintain consistent fabric quality.
Conclusion
Achieving high RFT% in cotton fabric dyeing with reactive dyes is a complex task influenced by a multitude of factors. By understanding and effectively managing these factors, textile manufacturers can significantly improve the consistency and efficiency of their dyeing processes. Apart from those, there are may be other factors, which may be responsible for reducing the RFT%. To minimize shade variations and increase Lab-to-Bulk RFT%, it is essential to implement standardized procedures (SOP), conduct rigorous quality control and invest in operator training.
References
- M. Morshed, “RFT Dyeing & Its Effect,” International Journal of Textile Science, vol. 2015, no. 1, pp. 20–26, 2015, doi: 10.5923/j.textile.20150401.03.
- J. Park and J. Shore, “Evolution of right-first-time dyeing production,” Coloration Technology, vol. 125, no. 3. pp. 133–140, 2009. doi: 10.1111/j.1478-4408.2009.00194.x.
- Saha, Palash & Hossain, Md & Nath, Manindra. (2023). Impact of liquor ratio on color uptake and fastness properties of Reactive dyed cotton fabric. 1.
- Islam, A., Rehman R., Jiang H. (2015): Prospect and Scope of Laboratory and Bulk Production Floor in Achieving and Improving RFT in Exhaust Dyeing, The 8th cross strait conference on textile technology, 397.