Textile Testing: How to Conduct a Climatic Test on Fabrics

Before performing a textile climate test, it's important to understand the purpose of the textile test and the type of material being tested. Based on this information, all the climate chamber.

In this article, we will look specifically at how a climatic test on fabrics, what its purposes are, and what the best climatic chamber is for doing so.

It should be emphasized that the climatic test cannot be performed before referring to an initial or standard procedure.

In this specific case, we're talking about the ISO 139 standard , which regulates climate testing of fabrics and clothing materials. It specifies that the sample must be subjected to a normal environment ( Standard Atmosphere ) for a defined period of time that varies depending on the type of fabric.

Discover the FDM Climatic Chambers specifically for Textile Testing

Reference standards and validity of the Climatic Test on Fabrics

Before delving into the mechanisms of how a textile test works, let's find out what conditions the reference standard establishes for the climatic test to be considered valid and reliable.

Specifically, the standard establishes the climatic conditions and limits to which the sample must be subjected. However, textile testing laboratories often attempt to perform part of the test with unreliable conditioning equipment.

The climatic chambers designed by FDM, on the other hand, are conceived specifically to carry out these types of tests, in a single environment, therefore taking into account the indications expressed in the ISO 139 regulation.

The resistance test, for example, is completed solely inside the climatic chamber, without having to move the sample several times and therefore risk losing the reliability of the final results.

That said, let's see in detail what the conditions indicated in ISO 139 are.

Initial Atmosphere (Standard Atmosphere)

As mentioned above, it is necessary to refer to a “Standard Atmosphere”, that is, it is necessary to bring the textile sample to an initial climate before proceeding to the actual climatic test.

The temperature , to be set on the climatic chamber, must be 20°C, while therelative humidity must be 65%.

The period in which the sample must be subjected to the initial climate varies according to the type of material and is defined by the reference standard.

Limits of variation

Throughout the test period, the environment in which the sample will be subjected must not deviate from the limits imposed by ISO 139:2005.

In fact, the temperature can vary by a maximum of ± 2°C, while the relative humidity can vary by ± 4%.

These two limits can be set directly in the air-conditioned chamber controller, which will constantly monitor the two parameters, thanks also to sensitive temperature and humidity probes.

Tolerances of the final result

However, even if you follow the testing procedure to the letter, there will still be external factors that will affect the final outcome.

According to BRITISH STANDARDS, in particular the BS4194:1967, a climatic test on fabrics can allow two types of tolerances:

Tolerance 1.Temperature ± 2°C, Relative humidity ± 5%

Tolerance 2.Temperature ± 1°C, Relative humidity ± 2%

They differ depending on the type of test performed.

Essential requirements of the climatic chamber for textile testing

Let's now see how a climatic test chamber should be built and what the essential characteristics are. 

There are three main factors to consider:

• The rate of change of temperature
• The internal dimensions of the chamber
• The product itself to be tested

Rate of change of temperature

The first thing to consider with any test chamber is temperature; specifically, the available temperature range and the rate of temperature change.

A standard chamber ranges from -25°C to +70°C. The most efficient ones can reach an even wider temperature range.

The rate of temperature change is a key parameter for successful testing. This value defines the performance of a climatic chamber and should not exceed ±0.2–0.3°C.

The devices produced by FDM are more than performing, with an internal temperature variation in the chamber of just ±0.1°C.

Discover the FDM Climatic Chambers specifically for Textile Testing

Internal dimensions of the chamber

The internal dimensions of the chamber should also be considered, a factor too often overlooked.

To obtain accurate results, the chamber must have sufficient airflow, in relation to the overall size of the tested samples.

When in doubt, it is good practice to purchase a chamber slightly larger than you think will suffice.

The product to test

Finally, the type of material to be tested also affects the choice of climatic chamber.

For this reason, FDM guides customers in choosing the most suitable climatic chamber based on the type of test.

Also remember that the camera must be calibrated properly to provide accurate results.

How to practically carry out a climate test on fabrics

Let's now see how to carry out a textile test, provided you have a suitable and high-performance climatic chamber.

Here is the step by step procedure.

• First, check the ambient temperature where the climatic chamber is positioned and verify whether the operating temperature falls within the data declared by the manufacturer.
• Prepare and verify the calibration of the temperature and humidity recording probes (usually performed at least once a year).
• Arrange the fabric samples so that air can freely access all surfaces. Distribute the fabric surfaces, placing only one layer per shelf.
• The preconditioning process (i.e., the Standard Atmosphere) begins. Sufficient preconditioning time can usually be achieved after four hours at 20°C and 65% relative humidity.

Unless otherwise specified, yarns, threads and similar materials must be displayed in skein form.

Textile testing takes up to eight hours for animal or viscose fibers and only two hours for fibers with less than 5% recovery at 65% humidity.

Heavy fibers take longer.

Endurance test final report

Finally, write a test report.

The test report describes all the processes, materials, and procedures used during the tests. It highlights the conditions of each stage, allowing you to accurately hypothesize why a material reacted a certain way and then draw the appropriate conclusions.

In general, the report includes:

1. subdivision of the tested material
2. equipment used
3. test conditions
4. test procedure
5. test results
6. test criticality
7. observations

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Reference Standards

• ISO 139:2005 — Textiles – Standard atmospheres for conditioning and testing. Basic standard for textile standard atmosphere: 20 °C ± 2 °C, 65% ± 4% RH.
• ISO 3801:1977 — Textiles – Woven fabrics – Determination of mass per unit length and mass per unit area, to be carried out after ISO 139 conditioning.
• ISO 105-B02:2014 — Tests for colour fastness to artificial light: Xenon arc fading lamp test, evaluation of the lightfastness of textiles.
• ISO 6330:2021 — Textiles – Domestic washing and drying procedures for textile testing, preconditioning for dimensional and color testing.
• BS 4194:1967 — Wide and narrow tolerances for climatic tests of textiles (Historic British Standard).
• ASTM D1776/D1776M-20 — Standard Practice for Conditioning and Testing Textiles, American equivalent of ISO 139.
• ISO 811:2018 — Textiles – Determination of resistance to water penetration – Hydrostatic pressure test.

Authoritative Sources

• ISO/TC 38 – Textiles. ISO technical committee dedicated to testing standards for textile materials, responsible for the ISO 139 series.
• UNI – Italian Standards Organization. Distributes the Italian EN/ISO standards applicable to the textile sector.
• AATCC – American Association of Textile Chemists and Colorists. An American organization that publishes methods complementary to ISO 139 for the textile sector.
• BSI – British Standards Institution. British body that maintains BS 4194 and other historical specifications still referred to.

Frequently Asked Questions About Fabric Climate Testing

Why is the ISO 139 standard atmosphere 20°C and 65% RH?

The parameters of 20°C and 65% RH have historically been defined as representative of the average temperate European climate in which the textile industry operates, but the main technical reason is the repeatability of the water content absorbed by natural and synthetic fibers. The regain (percentage of water absorbed relative to dry weight) of fibers such as cotton (7-8%), wool (14-18%), and viscose (11-13%) stabilizes reproducibly under these conditions, allowing for international comparisons between laboratories. Too low a humidity would alter the mechanical properties (brittleness), while too high would favor microbial growth and condensation. ISO 139 also considers thetropical atmosphere (27°C/65% RH) for equatorial countries and thealternative atmosphere (23°C/50% RH) when required by a specific product standard.

How much conditioning time does a wool fabric need?

ISO 139 requires that the sample be exposed to the standard atmosphere until constant mass, defined as a weight change of less than 0.25% in successive weighings at least 2 hours apart. Typical times depend on the structure and absorption of the fiber: 2 hours for low-regain synthetic fibers (polyester, polyamide with <5% regain); 4-6 hours for cotton and linen; 8-24 hours for wool, silk, and viscose; over 48 hours for very heavy fabrics or three-dimensional artifacts. Before conditioning, it is good practice to pre-condition at 50°C/max 10% RH to remove residual moisture. Skeins and yarns require longer times than fabrics due to their smaller exposed surface area. The chamber must ensure an air flow of at least 0.2 m/s over the sample surface.

What is the BS 4194 tolerance for high precision testing?

BS 4194:1967 defines two tolerance levels. Tolerance 1 (standard) allows ±2°C for temperature and ±5% for relative humidity, suitable for general quality control testing. Tolerance 2 (restricted) requires ±1°C for temperature and ±2% RH, reserved for certification testing, comparative research, and technical disputes. Tolerance 2 requires high-precision climatic chambers with spatial uniformity within ±0.5°C, temporal stability ±0.3°C, and probes with expanded uncertainty ≤0.2°C (ACCREDIA calibrated). ISO 139:2005 has formally replaced BS 4194 in standard tolerances, but British laboratories continue to cite both in test reports for historical compatibility. FDM chambers achieve uniformity ±0.5°C and stability ±0.3°C, compatible with Tolerance 2.

How to choose the right ISO 139 climatic chamber for large-volume testing?

The choice depends on the ratio between sample volume and chamber volume. ISO 139 requires free air flow over all sample surfaces, with a minimum spacing of 50 mm between specimens and 100 mm from the walls. For skeins and yarns, a filling factor < 20% of the chamber volume is recommended to avoid compromising uniformity and conditioning times. Technical parameters to be verified: horizontal air flow 0.2-1 m/s measured with a hot-wire anemometer; uniformity < ± 1 °C on 9 points; set-up ramp < 60 minutes to reach 20 °C/65% RH from ambient conditions. For industrial textile laboratories, the typical choice is an 800-2000 liter chamber with perforated shelves, while for R&D and CPP (Small Test Sample) volumes of 100-400 liters are sufficient. Compliance is certified with IEC 60068-3-6 mapping.