Color difference in webbing/tape during production and application is a common quality pain point in the textile industry. The following analysis covers three dimensions: Types, Causes, and Prevention & Control Measures.
I. Common Types of Color Difference
| Type | Description |
| Inter-batch Variation (Batch/Lot Difference) | Inconsistency in shade depth or hue between different dyeing batches (vats). |
| Intra-batch Variation (End-to-End/Sectional Difference) | Chromatic aberration occurring at the beginning vs. end, left vs. right sides, or between layers of the same roll of webbing. |
| Side-to-Center Difference | Color inconsistency between the edges and the center of the webbing (common in wide webbing). |
| Face-to-Back Difference | Different dye uptake on the front versus the back side of plain weave or rib weave webbing. |
| Storage/Aging Discoloration | Yellowing or fading caused by light exposure, humidity, or acidic/alkaline environments over time. |
II. Main Causes
1. Raw Material Factors
- Variations in yarn lot numbers (e.g., Polyester/Nylon/Cotton) lead to different dye absorption rates.
- Inconsistent whiteness of yarn, especially critical when dyeing light colors after bleaching.
2. Dyeing Process
- Fluctuations in dyeing temperature, duration, and pH levels.
- Errors in weighing dyestuffs/auxiliaries or drift in color matching formulas.
- Uneven temperature distribution or flow rate inside the dye vat (common in overflow/jet dyeing machines).
- Inconsistent temperatures between pre-setting and heat-setting processes.
3. Weaving Factors
- Uneven tension inconsistent fabric density varied dye uptake.
- Wide webbing is prone to side-to-center shading issues due to tension variations across the width.
4. Finishing
- Application of sizing agents, softeners, or water-repellent finishes affecting surface color appearance.
- Excessive heat-setting duration causing slight yellowing (particularly in light-colored polyester).
5. Inspection Environment
- Visual discrepancies under different light sources (natural daylight vs. fluorescent lamps vs. UV light), known as metamerism.
III. Prevention & Control Measures
✦ Customer / Order Placement Stage
- Confirm Standard Color Standards:
Approve and seal Lab Dips / Salesman Samples with signatures. Specify:
- Permissible ∆E Tolerance (Typically ∆E ≤ 0.8–1.0 for light shades; ∆E ≤ 1.0–1.5 for dark shades).
- Light Source Conditions (D65 / TL84 / CWF, etc.).
- Acceptance of Metamerism.
- Consolidate Orders: Place orders for the full quantity required in one batch to minimize multi-batch dyeing.
✦ Production Control
- Require the factory to:
- Combine Orders in One Vat: Use the same dyeing machine and temperature curve for the entire order.
- Pre-production Sampling: Conduct bulk trials (Lab Dips) before bulk dyeing and measure ∆E using a spectrophotometer.
- Optimize for Width: Select appropriate dyeing machines for wide webbing; adjust fabric speed/nozzle pressure to reduce side-to-center differences.
- Cooling Protocol: Ensure adequate cooling after heat-setting to prevent thermal residual yellowing.
