Perspiration Fastness: Acid and Alkaline Conditions
Sweat attacks dye differently in acid and alkaline conditions, and both must be tested for skin-contact apparel.
Below is a working summary of the key decisions, the values worth writing down and the tests that confirm performance.
Why two solutions are used
Human sweat varies in pH, so tests run in both acidic and alkaline solutions to cover the range.
Buyers who set expectations at the development stage spend far less time resolving complaints after the season has started.
Test procedure
Specimens are soaked, pressed against multifibre strip, incubated at body temperature, then graded for change and staining.
Document what happens when the result falls outside the range, including sorting, reworking and claim handling.
- 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
Typical failure profiles
Reactive dyed cellulose and some acid-dyed nylons change shade, while polyester disperse dyes usually hold well.
Log adjustments and their reasons, which turns each production run into useful data for the next one.
Link to finishing
Insufficient washing-off leaves unfixed dye on the surface that migrates under sweat exposure.
Ask the laboratory to state the sample condition, including whether the specimen was wet, stretched or conditioned.
- Ask for a separate price line for the requirement
- Confirm minimum quantities before committing the colourway
- Build one extra approval round into the calendar
Acceptance criteria
Grade 4 for colour change and grade 3 to 4 for staining is a common retail requirement.
Book capacity early where the requirement needs a specific machine or a specialised process.
Summary
Handled early, the requirement costs little and protects the launch date; handled late, it becomes an argument about responsibility.
