PURPOSE
To determine the resistance of the colour of textiles to the action of artificial human sweat.

EQUIPMENT
• Chemicals for the alkaline solution - see preparation of solutions.
• Chemicals for the acid solution - see preparation of solutions.
• Distilled water, grade 3
• Scale
• PH-meter
• 2 Measuring jugs holding at least 1 litre
• Perspirometer
• 11 acrylic-resin or glass plates
• Flat-bottomed dishes
• Oven, maintained at (37±2)⁰C
• Light box with light source D65
• Grey scale for assessing change in colour (ISO 105-A02)
• Grey scale for assessing staining (ISO 105-A03)
• Multifibre adjacent fabric, type DW (ISO 105-F10)
PREPARATION OF SOLUTIONS

pH regulator

0.1  mol /l Sodium hydroxide solution (NaOH) - 4.0g NaOH per litre: distilled water.

Alkaline solution, freshly prepared, containing, per litre:

• 0.5g of L-histidine monohydrochloride monohydrate (C6H9O2N3∙HCl∙H2O);

• 5g of sodium chloride (NaCl) and either

• 5g of disodium hydrogen orthophosphate dodecahydrate (Na2HPO4∙12H2O)

or
• 2.5g disodium hydrogen orthophosphate dihydrate (Na2HPO4∙2H2O)

The solution is brought to pH 8 (±0.2) with 0.1 mol/l sodium hydroxide solution (NaOH).

Acid solution, freshly prepared, containing, per litre:

• 0.5g of L-histidine monohydrochloride monohydrate (C6H9O2N3∙HCl∙H2O)
• 5g of sodium chloride (NaCl)
• 2.2g of sodium dihydrogen orthophosphate dihydrate (NaH2PO4∙2H2O)
The solution is brought to pH 5.5 (±0.2) with 0.1 mol/l sodium hydroxide solution (NaOH).

TEST SPECIMEN
Two specimens for each colour and material measuring 4cm x 10cm; one for alkaline and one for acid.
All products and parts of products including details such as labels, badges and drawstrings need to be tested. Both solid and multi-coloured products need to be tested. If the product is multi coloured, make sure all colours are included in the specimen to be tested. More specimens could be required if the specimens are printed, striped or have multiple colours. Different parts in contrast colours need to be tested, both against each other and against the multifibre adjacent fabric. Cut specimens of all colours and stitch them together face side to face side.
If face and back side are different in colour or construction, both face and back side needs to be tested. If sample is all over printed and backside is strong coloured and visible at face side, no need to test back side against multifibre adjacent fabric. (No need to test light coloured backsides either.)
If details (including prints) are in contrast colour they need to be tested both against adjacent fabric and the fabric of which the detail is attached. If not in contrast colour they need to be tested only against adjacent fabric.
METHOD
Test should be performed according to ISO 105-E04 or Chinese standard GB/T 3922, below follows the method in short. The solutions should be freshly prepared i.e. a new solution should be prepared every day.
1. Cut specimens measuring 4cm x 10cm.
2. Attach a specimen to multifibre adjacent fabric of the same size, by sewing along one of the shorter (4 cm) sides. The multifibre should be next to the face side.
3. Switch on the oven and preheat pre-heat perspirometer & acrylic plates for 30 min.
4. Place the specimens in a dish with 100 ml of the sweat solutions and thoroughly with the help of glass rod/acrylic plate to wet specimen and multifibre for 30 min.
5. Pour off the excess solutions from specimen by using wringer /glass.

6. Place each specimen between two glass or acrylic plates and place them in the perspirometer. Each perspirometer can hold maximum 10 samples. If less, all 11 plates still have to be placed in the perspirometer. Put a pressure of 12.5 kPa on the perspirometer using the load, lock it and then remove the load. 12.5 kpa pressures must be evenly distributed on the sample surface. Plates must be parallel to each other, inclination of plates due to thick and thin (uneven sample surface) surface must be avoided.
7. Place the perspirometer in the oven for 4 hours at (37±2)°C in upright position

8. Take out the specimens from the oven and perspirometer. Open out each specimen and dry them in room temperature, not exceeding 60°C, with the specimen only being in contact at the point of the stitching.


RESULTS
Assess cross staining, change in colour and colour staining.