Scope
This part of ISO specifies a method for determining the resistance of the colour of textiles of all kinds and in all forms to ironing and to processing on hot cylinders.
Tests are given for hot pressing when the textile is dry, when it is damp and when it is wet. The end-use of the textile usually determines which test should be made.
Apparatus
Heating device, consisting of a pair of smooth parallel plates, equipped with an accurately controllable electrical heating system and giving a
pressure on the specimen of 4 kPa ± 1 kPa.
In order to obtain the required pressure (4 kPa ± 1 kPa) the total area of the wool flannel padding should bear a suitable relationship to the mass of the plate pressing down on the padding. If the fabric to be tested has an appreciable thickness, it will be necessary either to increase the area of the test specimen or to augment the pressure-bearing surface using a suitable template made from the same material as the test specimen. If the plates of the heating device are smaller than the specimen, the pressure (ratio of weight of top plate to its area) will depend on the
design of the apparatus.
Heat should be transferred to the specimen from the upper side only; if the lower plate is equipped with a heating system which cannot be turned off, the heat-resistant sheet with which the device shall in any case be fitted acts as a heat shield.
The heating device may be the same as that used in the test for colour fastness to dry heat (excluding pressing).
If a heating device is not available, a household iron may be used, but its temperature should be measured with a surface pyrometer or with temperature-sensitive papers. The iron should be weighted so that its area and total weight are in the appropriate ratio to exert a pressure of
4 kPa ± 1 kPa. However, due to temperature, differences between different points on the surface of the iron, accuracy and reproducibility are limited.
When a hand iron is used, this fact shall be stated in the test report.
Test specimen
If the textile to be tested is fabric, use a specimen 40 mm × 100 mm.
If the textile to be tested is yarn, knit it into fabric and use a piece
40 mm × 100 mm or wind it closely round a piece of thin inert material measuring 40 mm × 100 mm to form a layer having only the thickness of the yarn.
If the textile to be tested is loose fiber, comb and compress enough of it to form a sheet 40 mm × 100 mm and sew the sheet onto a piece of cotton adjacent fabric to support the fiber.
Procedure
General
The choice of pressing temperature used depends to a large extent on the type of fiber and on the construction of the fabric or garment. In the case
of blends it is further suggested to use the temperature appropriate to the fiber with the lowest heat resistance. The following temperatures cover three commonly used pressing conditions:
110 °C ± 2 °C
150 °C ± 2 °C
200 °C ± 2 °C
When necessary, other temperatures may be used, provided that they are specially noted in the test report.
Specimens of materials that have been subjected to any heat or drying treatment shall be conditioned in the standard temperate atmosphere for testing textiles, in accordance with ISO 139 before they are tested.
The bottom plate of the heating device is covered with the heat resistant sheet, wool flannel padding and dry, undyed cotton cloth, whether the late is heated or not.
Dry pressing
Place the dry specimen on top of the cotton cloth covering the wool flannel padding. Lower the top plate of the heating device and leave the
specimen for 15 s at the specified pressing temperature.
Damp pressing
Place the dry specimen on top of the cotton cloth covering the wool flannel padding. Soak a piece of cotton adjacent fabric measuring
40 mm × 100 mm in grade 3 water, and squeeze or extract it to contain its own mass of water. Place the wet fabric on top of the dry specimen. Lower the top plate of the heating device and leave the specimen for 15 s at the specified pressing temperature.
Wet pressing
Soak the specimen and a piece of cotton adjacent fabric 40 × 100 mm in grade 3 water and squeeze or extract them to contain their own mass of water. Place the wet specimen on top of the dry cotton cloth covering the wool flannel padding and place the wet adjacent fabric on the specimen. Lower the top plate of the heating device and leave the specimen for 15 s at the specified pressing temperature.
Assessment
Assess the change in colour of the specimen by comparison with the appropriate grey scale immediately and again after the specimen has been allowed to condition for 4 h in the standard atmosphere for testing textiles.
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