For three decades, ironing fastness under ISO 105-X11 meant one of three numbers: 110 °C, 150 °C or 200 °C. Those numbers are on worksheets, in buyer manuals and in the presets of many hot-pressing testers.
In June 2026 a new edition, ISO 105-X11:2026, was published, replacing the 1994 edition. Its published summary lists 120 °C, 160 °C and 210 °C as the three commonly used pressing temperatures. If your procedures still say 110/150/200, they now describe the withdrawn edition.
What the test is for
ISO 105-X11 determines the resistance of the colour of textiles to ironing and to processing on hot cylinders. It is relevant wherever colour can change or migrate under heat during pressing — in the garment factory, at the dry cleaner or at home. The standard offers three procedures, chosen according to the end use:
| Procedure | What is pressed |
|---|---|
| Dry pressing | A dry specimen alone |
| Damp pressing | A dry specimen covered by a wet cotton adjacent fabric |
| Wet pressing | A wet specimen covered by a wet cotton adjacent fabric |
Colour change of the specimen is graded with the ISO 105-A02 grey scale and staining of the cotton adjacent fabric with the ISO 105-A03 grey scale.
What the 1994 edition specified
The details of the 2026 edition should be read from the new text itself. For reference, the withdrawn 1994 edition specified:
- A heating device with smooth parallel plates applying (4 ± 1) kPa to the specimen.
- A pad of two layers of wool flannel, about 3 mm thick, on a heat-resistant sheet, covered with undyed, bleached, unmercerised cotton cloth.
- A specimen of 40 mm × 100 mm.
- Pressing for 15 s at the selected temperature, with heat transferred from the upper side only — if the lower plate cannot be switched off, the insulating sheet acts as a heat shield.
- For damp and wet pressing, cotton adjacent fabric (and the specimen, for wet pressing) soaked in grade 3 water and squeezed to contain its own mass of water.
- Colour change graded immediately and again after 4 h conditioning in the standard atmosphere (ISO 139).
- Specimens previously heat-treated or dried conditioned in the standard atmosphere before testing.
Both the 1994 summary and the 2026 summary say that for blends the temperature should suit the fibre with the lowest heat resistance, and that other temperatures may be used if they are reported. Before you change anything else, obtain the 2026 text and compare it clause by clause with your procedure — especially pressure, time and the assessment sequence.
What changes in the lab
Worksheets and presets
Every preset, worksheet and LIMS entry that says 110, 150 or 200 °C needs a review. A tester that has been running "ISO 105-X11, 150 °C" for years will keep doing exactly that unless someone changes it.
Reports
A report must name the edition. "ISO 105-X11" with no year, at 150 °C, is now ambiguous: it was correct under 1994 and is a non-standard temperature under 2026 — permitted, but it must be stated. Write "ISO 105-X11:2026, dry pressing, 160 °C" or, during a transition, "ISO 105-X11:1994, 150 °C, as specified by customer".
Customer specifications
Many buyer manuals quote the old temperatures. Do not silently switch: ask the customer which edition and temperature they want, and record the answer. On heat-sensitive dyeings, ten degrees can be the difference between two grades.
Equipment range and calibration
Check that your tester covers the new top temperature with margin and that its temperature has been verified at the new set points, not only at the old ones. A calibration certificate with points at 110, 150 and 200 °C does not show how the plate behaves at 210 °C.
Bench errors that the new edition does not fix
Measuring the wrong temperature
The display shows the controller's sensor, not the plate surface where the specimen sits. Verify the surface temperature with a surface probe or temperature-indicating strips at each set point used.
Losing the pressure
The specified pressure depends on the relationship between the top plate's mass and the padding area. Thick specimens need a larger specimen area or a template, so that the load is not carried by a few high points.
Wet means a defined amount of water
"Wet" in damp and wet pressing is not "dripping". Squeeze or extract to the specified water content and weigh it. Excess water cools the plate and changes the result.
Grading only once
Some heat-induced shade changes partly recover as the fabric cools and regains moisture. That is why the procedure grades colour change both immediately and after conditioning. A single grade taken straight off the press tells only half the story.
Hand irons
The 1994 edition allowed a household iron when no heating device was available, but warned that its uneven surface temperature limits accuracy and reproducibility, and required the report to say so. If a hand iron was used, write it on the report.
AATCC 133 is a separate method
AATCC 133 also covers colour fastness to heat by hot pressing. It is a different document with its own conditions; an ISO 105-X11 result does not satisfy an AATCC 133 requirement, or the reverse.
Checklist
- Does the procedure cite ISO 105-X11:2026, and has it been compared with the new text?
- Are the temperatures updated, or the customer's choice of edition recorded?
- Has the tester been verified at the new set points?
- Was water content in damp/wet pressing weighed, not estimated?
- Was colour change graded immediately and after conditioning?
TLI-TexLabInstruments manufactures its iron fastness tester, with a 20–220 °C plate range, in its own workshop in Istanbul.