pH Value of Fabric Test Methods and Acceptable Limits
pH Value of Fabric is verified through ISO 3071 aqueous extract. Knowing how the method works avoids rejecting fabric that actually meets the requirement.
Method overview
ISO 3071 aqueous extract defines sample size, conditioning and calculation, so values are comparable only within the same revision. Working figures for pH Value of Fabric normally sit around 4.0 to 7.5 for skin contact in mainstream production. Note ISO 3071 aqueous extract on the tech pack so nobody tests against an older revision.
Result interpretation
Read the value together with construction notes; 4.0 to 7.5 for skin contact is only meaningful for similar fabrics. Record elastane content alongside pH Value of Fabric, because blends shift the measured value. A result outside 4.0 to 7.5 for skin contact usually points to process drift rather than to the fibre itself.
Typical limits
Buyers commonly write 4.0 to 7.5 for skin contact with a stated tolerance, then verify against ISO 3071 aqueous extract. Keeping reference values for pH Value of Fabric lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 3071 aqueous extract, since both affect the reading.
Sources of variation
Conditioning time, operator technique and shade all influence the result. Working figures for pH Value of Fabric normally sit around 4.0 to 7.5 for skin contact in mainstream production. Note ISO 3071 aqueous extract on the tech pack so nobody tests against an older revision.
Documentation
Record the standard revision on every report, because older versions can differ from current practice. Record elastane content alongside pH Value of Fabric, because blends shift the measured value. A result outside 4.0 to 7.5 for skin contact usually points to process drift rather than to the fibre itself.
