Colour Fastness to Perspiration：A Complete Guide

Summer is approaching, and summer is a particularly easy sweat season a painful sweat can make the mood comfortable, but at the same time there are many people who will be distressed, why every time after sweating clothes on the body will lose colour, in fact, this is likely to be your clothes sweat resistance colour fastness caused by substandard. In this article, we will take you through the colour fastness test for the perspiration of textiles!

Colour fastness to perspiration

The human skin has millions of effective sweat glands and the forehead, armpits, forehead, back and palms sweat more; therefore clothing often worn in summer such as shirts and T-shirts can show serious fading in these areas. It is well known that the composition of human sweat is complex, with the main component being salt, which varies from person to person, and sweat can be acidic or alkaline. Brief contact between textiles and sweat may have little effect on their colour fastness, but a long period of time in close contact with sweat against the skin will have a greater effect on certain dyes. Clothing with substandard colour fastness can easily lead to the transfer of dyes from textiles to human skin through sweat etc. Molecules of dyes and heavy metal ions etc. can be absorbed by the body through the skin and become a health hazard.

The colour fastness to perspiration reflects the colour change of the textile in different test solutions containing histidine, under the combined effect of pressure and temperature, and the staining of the lining fabric.

Dangers of substandard sweat stains

The human skin has millions of effective sweat glands and the forehead, armpits, forehead, back and palms sweat more; therefore clothing often worn in summer such as shirts and T-shirts can show serious fading in these areas.

It is well known that the composition of human sweat is complex, with the main component being salt, which varies from person to person, with sweat being either acidic or alkaline. The prolonged contact between textiles and sweat will have a greater effect on certain dyes.

Clothing with substandard dye fastness can easily lead to the transfer of dyes from textiles to human skin through sweat, etc. Molecules of dyes and heavy metal ions, etc. can be absorbed by the body through the skin and be hazardous to health.

National testing standards

The standard for colour fastness to perspiration of textiles currently used in China is GB/T3922-2013, which is equivalent to the international standard IS0105-E04:1994, while the standards for colour fastness to perspiration used in the UK, Germany and France are BSEN ISO 105-E04:1996, DIN EN ISO 105-E04:1996, NF EN ISO 105-E04:1996, which are all equivalent to IS0105-E04:1994.

Standards

• Perspiration-GB/T 3922, AATCC15, ISO105-E04, JIS L 0848
• Sea Water-GB/T5714, ISO105-E02,AATCC107
• Water-GB/T5713, ISO105E01, AATCC106
• Saliva-GB/T 18886

For the comparison of specific ISO/AATCC/JIS test standard methods, please go to this article.

Overview of the test procedure

Taking the test method of “GB/T 3922-2013 Colour fastness test for textiles Colour fastness to perspiration” as an example.

Test principle

The textile specimen and the standard lining fabric are sewn together and placed in two test liquids containing histidine, acidic and alkaline, respectively, and after removal of the test liquids, placed between two flat plates in the test apparatus and subjected to a specified pressure.

Test apparatus

Perspiration Tester

The Perspiration Tester TF416A consists of 1 stainless steel frame with 21 acrylic separator plates to hold 20 samples. Thus both ISO/AATCC test methods can be done at one time. 20 plastic basins are equipped for the pre-treatment of samples.

Steel frame and weights are made of 316L stainless steel, which is acid and alkali-resistant and corrosion-resistant for a long time.
Load weight to meet the requirements of AATCC, other weights are also available according to user requirements.
Smooth precision engineering parts with excellent performance.
TESTEX Perspiration Testers are sold to 42 countries around the world and have 12 years of export history, a good reputation, and reliable quality.

Perspiration Tester Kit 

Perspiration Tester Kit(a.k.a. Perspirometer), to determine Color Fastness test to water, seawater, perspiration fastness in textiles and sublimation during storage.

Perspiration Tester Kit consists of a precise Lab incubator and a set of TF416A Perspiration Testers. Perspiration Tester Kit complies with AATCC 15, EN ISO 105 E04, DIN 54020, etc. The larger the value, the better the Perspiration fastness.

Test procedure

1. Specimen preparation

Take a 40mm x 100mm specimen and stitch the front of the specimen to a piece of multi-fibre lining or to two pieces of single-fibre lining.

2. Preparation of sweat solution

Prepare an acid (alkali) sweat solution according to the standard using a quantitative amount of sodium chloride, histidine hydrochloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, etc.

3. Specimen infiltration and pressure

Put a piece of the combined specimen into the acid (alkali) test solution, make it completely wetted, and leave it at room temperature for 30min, lifting and plucking from time to time to ensure that the test solution fully and evenly penetrates into the specimen. Pour off the residual liquid and use two glass rods to remove the excess liquid from the combined specimen. Place the combined specimen between two glass or acrylic plates, fix it on the sweat stain colour fastness meter and apply 5Kg of negative pressure so that it is subjected to a nominal pressure of (12.5±0.9) kPa.

4. Placement

The test device with the combined specimen is placed in the thermostat and the combined specimen is placed horizontally or vertically at (37±2)°C for 4h.

5. Drying

After 4h, remove the test device with the combined specimen, unfold each combined specimen so that the specimen and the liner are only connected by a seam and hang in the air at no more than 60°C to dry.

6. Assessment

Assessed on discoloured grey sample cards and stained grey sample cards, grade 5 being the best and grade 1 the worst.

Precautions

1 It is important to ensure that the specimen is thoroughly immersed in the test solution. Some specimens, if left untreated, may not be fully penetrated even if immersed for a long time. In such cases, the specimen should be pounded thoroughly by hand or with a flat-tipped glass rod, or The specimen can also be soaked through by suction.

2 Acid and alkali sweat tests should be carried out separately and the same sweat meter should not be used to avoid mutual influence.

3 To ensure that the pressure on each specimen is normal, the sweat stainer should be placed flat in a thermostat to keep it warm.

4 The temperature of the thermostat should always be controlled within the range of (37+2)°C.

5 The test solution for the test should be ready to use as required.

Should the last seam of a combination specimen be removed when conducting test?

Some of the combination specimens will have more staining on the lining after the test if the last seam is not removed and dried, than if the last seam is removed and dried, with some significant differences (2 to 3 levels), mainly in samples that still contain more liquid after being taken out of the box for sweat stains and water resistance, and this phenomenon is more frequent in jumpers and fleece products.

For example, the following chart shows a comparison between samples with perspiration stain/wash fastness and samples with the lining removed and dried without removal:（See figure）

The general standard states that the specimen is connected to the lining by a single seam and hung to dry. However, some standards stipulate that all seams should be disconnected to dry (liner and specimen separated) if required.

In practice, some standards require all sutures to be disconnected and others do not. How are ratings handled when there is a swim shift? Or do you disconnect all the sutures to dry the combined specimens when there is a swim shift?

And what do the standards say?

Standards that do not require the removal of the last stitch

(1) GB/T 3921-2008

Clause 7.4: For all methods, squeeze excess water from the combination specimen by hand. If required, leave the stitching on one short side, remove the rest of the stitching and unfold the combination specimen. Clause 7.5 of this standard places the specimen between two filter papers and squeezes to remove excess moisture, then hangs it to dry in air at a temperature of not more than 60°C, with the specimen connected to the liner by only one seam.

(2) ISO 105-C08:2010

Clause A.9, for all methods, dry the specimen by either of the following methods:

1. a) Separating the lining and the specimen (so that only the sewn edges of the specimen are in contact) and hanging in air at a temperature of not more than 60°C.
2. b) In some countries ironing is used to dry the fabric at a temperature suitable for the specimen but not exceeding 150°C, with the lining fabric on top of the specimen during ironing. Record the temperature used in the test.

(3) GB/T 3922-2013

Clause 6.3: Remove the test apparatus with the combined specimen, unfold the combined specimen so that the specimen and the lining are connected by only one seam (if necessary, remove all seams except one short edge) and hang to dry in air at a temperature of not more than 60 °C.

(4) GB/T 5713-2013

Clause 7.3: Unfold the combined specimen (if required, disconnect the stitching so that the specimen and the lining are joined at one short edge only), discard the existing air-dried specimen, redo it and hang the specimen to dry in air at a temperature of not more than 60 °C, with the specimen and the lining separated and joined only at the stitching.

The above standards all require that all stitching is removed, if required, except for one short edge.

Standards requiring the removal of the last stitch

(1) AATCC 106-2013

Clause 8.5: Remove the test device from the oven, separate the multi-fibre patch or fabric patch (if used) from the test specimen, place the multi-fibre standard patch and the specimen on a metal screen, respectively, and condition for one night at an ambient temperature of (21±1)°C/(70±2)°F and humidity of (65±2)%.

(2) ISO 105-E02:2013

Clause 6.3: Unfold the combined specimen so that the specimen and the lining are connected by only one seam (remove all seams except one short edge if required).

Any specimens found to be air-dried should be discarded. Hang the specimen in air at a temperature of no more than 60°C to dry (only two or three parts are connected at the seam line). (If necessary, remove all stitches except one short edge.) This phrase means that the last stitch is not removed; however, the phrase (only two or three parts are attached at the stitching position) is ambiguous. The phrase can be interpreted as either detaching or not detaching, as both parts can be joined.

(3) GB/T 12490-2014

Clause 6.9: For all methods, the specimen is hung in air at a temperature of not more than 60°C to dry, with the specimen and the lining in contact only at the seam line.

In case of uneven colour bleeding at the stitching of the lining fabric, the specimen is re-sampled and dried separately from the lining stitching.

(4) GB/T 5714-1997

Clause 6.3: Unfold the combined specimen so that the specimen and the lining are connected by only one seam (if necessary, disconnect all seams) and hang it to dry in air at a temperature of not more than 60 °C. Any specimens found to be air-dried should be discarded and redone.

The AATCC standard requires that the multi-fibre standard liner and specimen are placed separately on a metal screen.

Standards that may or may not remove the last seam line

ISO 105-E01:2013

Clause 6.3: Unfold the combined specimen so that the specimen and the lining are connected by only one seam (if necessary, remove all seams except for one short edge).

Any specimens found to be air-dried should be discarded. Hang the specimen in air at a temperature of no more than 60°C to dry (only two or three parts are connected at the stitching). The phrase (if necessary, remove all stitches except one short edge) means that the last stitch is not removed; however, the phrase (only two or three parts are joined at the stitching) is ambiguous. It can be interpreted as splitting or not splitting, since it is possible to have two or three parts joined with or without splitting.

Conclusion

On the issue of removing or not removing the thread, Chen Xiaocheng, the drafter of GB/T 3922-2013 standard, said that if the swimming shift is serious, it can be removed and dried, and after internal discussion and analysis in the laboratory, the unified operation is as follows:

(1) sample cutting colleagues to accumulate experience in pre-judgment, which samples are prone to uneven staining, mark directly before the test to remove the line, the effect of removing the line;

(2) Testing and grading colleagues: if uneven staining is found after testing, the cutting colleagues should be informed to remove the thread and retest.

Regardless of whether or not the standard is clear about the removal of the thread, the operation is carried out according to the removal of the thread. (Removing the thread means separating the sample and the liner when the sample is dry)

Factors influencing the colour fastness to perspiration

1. When the surface of the fabric has too much floating colour of the dye that has not been stably combined with the fibre, the fastness to perspiration is tested and the dye is easily transferred under pressure, temperature, acid and alkali, etc. If the affinity between the dye and the lining is good, it is easy to have a serious phenomenon of colour staining, which makes the fastness of the fabric measured in the experiment lower.
2. Some auxiliaries added during dyeing and post-treatment are not removed cleanly after dyeing, and the residual auxiliaries can cause heat migration of polyester dyed by disperse dyestuff during high-temperature setting (during high-temperature setting, the residual auxiliaries dissolve the disperse dyestuff that has penetrated into the interior of the fibre and migrate to the fibre surface), affecting the colour fastness of the fabric to perspiration.
3. The retarding agent added during the dyeing process can also weaken the bonding between the dye and the fibres, which can lead to unsatisfactory results in terms of fastness to perspiration.
4. The constant temperature, pH and type of lining play a crucial role in the colour fastness to acid and alkali perspiration of nylon, polyester and ammonia fabrics, especially the accuracy of the pH value, which plays a key role in the accuracy of the test results. Therefore, it is important to focus on the accuracy of these 3 factors during the experimental operation in order to improve the accuracy of the experimental results.

How to improve the colour fastness to perspiration

The main way to improve the colour fastness of fabrics to perspiration is to choose the right dyestuffs, especially those with a high fixation rate and good stability. The dyeing process should be reasonably developed and controlled to strengthen the colour fixation conditions and to form covalent bonds with high stability so that the dye can be fully fixed. For example, a catalyst can be used for dyeing less reactive dyestuffs, an appropriate colour-fixing agent can be used, or the colour can be fixed at a higher temperature.

1 Choose dyestuffs for dyeing that have a high colour fastness rating of their own.

2 Choose dyestuffs with a high dyeing rate for dark-coloured textiles, and the saturation of the dyestuff should be such that it reaches the required depth of colour.

3 Choose the right dyestuff according to the composition of the textile.

4 Select the appropriate auxiliaries according to the type of dye and remove any residual auxiliaries after dyeing.

5 When soaping and washing, the fabric should be washed well to remove the floating colours from the surface.

Common sense: How to remove sweat stains from clothes

1. Do not use hot water to wash your clothes, too hot water will make the proteins in the sweat stains solidify on the clothes, forming a stain that is difficult to remove.
2. Sweat stains on clothes will not only form stains but also produce a sweat odour, so clothes with sweat stains should be washed in time.
3. Spray white vinegar on clothes that have sweat stains or are already yellow and then wash them to remove them effectively.
4. Soak sweat-stained clothes in 3% to 5% salt water for 1-2 hours, then wash with water to remove sweat stains.