pH Value Testing on Textiles: Why It Matters for Skin Safety
Fabric pH outside the skin-compatible range causes irritation, and the risk is highest after alkaline processing.
Below is a working summary of the key decisions, the values worth writing down and the tests that confirm performance.
Test principle
Aqueous extract from the fabric is measured with a calibrated electrode, using the standard method for the fibre type.
Buyers who set expectations at the development stage spend far less time resolving complaints after the season has started.
Acceptable ranges
Skin-contact textiles are typically required to fall between pH 4.0 and 7.5, with tighter limits for babywear.
Write the requirement into the fabric specification as a numeric range with the test method named, so buyer and mill measure the same thing.
- Request test reports on production fabric, not on development samples
- Verify the sampling plan and the number of specimens
- Store reports with roll or lot identification for traceability
Why pH drifts
Insufficient rinsing after scouring, bleaching or alkaline dyeing leaves residues that raise pH.
Record the machine settings for each approved lot, so a repeat order can be reproduced rather than re-invented.
Corrective actions
Additional washing-off, neutralising or an acidic after-treatment corrects most alkaline drift.
Keep reports on file with the sample identification, so results can be traced back to a specific roll or batch.
- 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
Sampling practice
Test several pieces per lot, because pH can vary between positions in the same dyeing machine.
Keep a buffer in the schedule for one additional approval round, because most programmes use it.
Summary
The technical content is straightforward. The discipline lies in writing it down, testing it on production fabric and repeating the result on the next order.
