Colour Fastness to Washing: Rating, Sameness and Staining
Washing fastness covers both colour change of the specimen and staining of accompanying fabrics, and both results matter to retail.
The following sections cover the definition, the specification values, production control, testing and commercial impact.
Test principle
Specimens are washed with adjacent multifibre strip, then colour change and staining are graded against grey scales.
Experience shows that small specification decisions here have an outsized effect on the customer experience.
Standard methods
ISO 105 C06 and AATCC 61 are the most widely referenced, and their conditions are not interchangeable.
Where a standard exists, name the standard number, since a value without a method cannot be verified by a third party.
- Agree tolerances in writing before the first sample is made
- Define the measurement condition and the direction measured
- Review the limit each season against real performance data
Grading the result
Colour change and staining are each rated from one to five, with grade 4 usually the minimum for apparel.
Escalate deviations immediately, as a small change early in the run is cheap to correct and costly to fix later.
Common failure causes
Insufficient soaping, dye selection with poor wet fastness and over-dyeing all cause bleeding.
Where results are borderline, decide in advance whether to accept, re-test or negotiate, rather than arguing later.
- Record settings and raw material lots for every approved production run
- Check in-process rather than relying on final inspection
- Escalate deviations the same day they appear
Multi-fibre specifics
The strip reveals which fibres stain, which points directly to the dyes that need changing.
Plan the calendar with the approval steps in mind, since late approvals delay production regardless of capacity.
Summary
Buyers who verify rather than assume obtain better fabric at the same price, and fewer surprises after the goods arrive.
