Washing shade and process variation

Learning objectives

• Define an approved-shade method with a defensible Delta-E rule.
• Locate wash-process drivers of shade, hand feel and dimensional change.
• Design a robust operating range without unsafe chemical experimentation.

Problem and CTQ

Shade, hand feel, dimensional change and appearance vary across machines, lots and time. Chemical and safety compliance is mandatory throughout.

DMAIC path

• Validate spectrophotometer and visual-booth agreement.
• Map recipe, load, water, temperature, pH, time, chemical lot and machine.
• Use regression or a small DOE only within safe, approved ranges.

Improvement choices

• Recipe lock and dosing calibration.
• Load window and water/temperature controls.
• Material-lot strategy and sample approval before bulk release.

Control plan

• Shade pass / Delta E, rewash %, chemical/water/energy per garment, cycle time, shrinkage and RFT.
• Chemical-safety and MRSL guardrails in every change.

Garment-factory example

A denim wash programme shows 8% rewash on a mid-shade. A load-weight tolerance of ±3% and a fixed enzyme-dose calibration cut rewash to 2.4% with no MRSL exceptions.

Common mistakes

• Comparing readings under inconsistent lighting or conditioning.
• Adjusting recipe without approved chemical-safety review.