Perspiration fastness is one of the cheapest tests in a fastness lab. A composite specimen is soaked in an artificial sweat solution, pressed between plates, kept warm for a few hours, dried and graded.
Because it is cheap, it is often run on autopilot. And because it runs on autopilot, small habits creep in that move the result — usually towards a better grade than the garment deserves.
What ISO 105-E04:2013 actually specifies
The current edition is ISO 105-E04:2013. Its core parameters are short enough to pin above the bench:
| Item | Requirement |
|---|---|
| Specimen | (40 ± 2) mm × (100 ± 2) mm, sewn to a multifibre (ISO 105-F10) or between two single-fibre adjacent fabrics |
| Solutions | Alkaline, pH 8.0 ± 0.2, and acid, pH 5.5 ± 0.2 — both containing L-histidine monohydrochloride monohydrate and sodium chloride, made with grade 3 water |
| Wetting | Approximate liquor ratio 50:1, 30 min at room temperature |
| Pressure | (12.5 ± 0.9) kPa between glass or acrylic plates |
| Incubation | 4 h at (37 ± 2) °C |
| Drying | Hanging in air at not more than 60 °C, parts touching only at the stitching |
Everything that goes wrong on the bench is a departure from one line of this table.
1. The solutions are not fresh
The standard says both solutions are freshly prepared. Histidine solutions are a good medium for microbial growth, and a bottle made on Monday and used on Friday is no longer the same liquid.
Make them on the day of testing, adjust pH with 0.1 mol/l sodium hydroxide as the method describes, and record the measured pH on the worksheet. If the pH meter has not been calibrated that week, the pH value is a guess.
2. Acid and alkaline specimens share a device
The two solutions are two separate tests. The standard has the acid specimen tested in a separate pre-heated test device. Putting alkaline and acid composites in the same stack is a deviation from the method, and any liquor that drains between neighbouring specimens mixes two different chemistries.
Label the devices "ACID" and "ALKALINE" permanently. It removes the temptation.
3. Fewer than eleven plates
A test device takes up to ten composite specimens, each separated by a plate. The standard is explicit: if you prepare fewer than ten specimens, all eleven plates must still be used to keep the nominal pressure correct.
The pressure comes from a weight of about 5 kg bearing on the stack. Remove plates and the geometry changes; the pressure on the specimen is no longer what the method assumes. Running "just two specimens, so three plates" is a tempting shortcut, and the standard does not allow it.
4. The device goes into the oven cold
The method places the composite in a test device preheated to the test temperature. A steel frame and a 5 kg weight taken from a cold cabinet take a long time to reach 37 °C, and that time is subtracted from the four hours.
Keep the devices in the oven when they are not in use. Then "preheated" costs nothing.
5. The specimen is not really wet
"Thoroughly wet" means the specimen spends 30 minutes in the solution at roughly 50:1, pressed and moved from time to time so the liquor penetrates evenly. Excess liquor is then wiped off between two glass rods.
Two failures happen here. A water-repellent or tightly constructed fabric floats with dry patches unless it is pressed under. And a specimen squeezed by hand instead of between glass rods carries an uncontrolled amount of liquor into the press. Both change how much dye can migrate.
6. Drying too hot, or folded
Dry the opened composite hanging in air at no more than 60 °C, with specimen and adjacent fabrics touching only at the line of stitching. A composite dried folded, or on a radiator, keeps transferring dye while it dries — that staining is not perspiration staining.
Reading the result
Grade colour change on each specimen with the ISO 105-A02 grey scale and staining on each fibre of the multifibre with the ISO 105-A03 grey scale. The report must give the colour change for each solution separately, the staining per fibre, the multifibre type and the option used.
One note in the standard deserves attention: on cellulosic fibres dyed with copper-containing direct dyes, or after-treated with copper salts, perspiration can remove copper from the dyeing. That can change light, washing and perspiration fastness, so a good perspiration result on such goods does not guarantee the others.
AATCC 15 is a different test
Buyers who work to AATCC 15 sometimes accept an ISO 105-E04 report, and vice versa. The two methods differ in solution chemistry and procedure; a grade from one is not a grade under the other. If the specification says AATCC 15, run AATCC 15.
Checklist
- Were both solutions made today, and is the measured pH on the worksheet?
- Were acid and alkaline composites in separate, preheated devices?
- Were all eleven plates in each device?
- Did each specimen soak for 30 minutes at about 50:1?
- Was drying at ≤ 60 °C, opened out, touching only at the stitching?
- Does the report give separate grades for acid and alkaline?
TLI-TexLabInstruments manufactures its perspiration fastness tester in its own workshop in Istanbul.