AATCC 133:1999 pdf download.Colorfastness to Heat: Hot Pressing
12.3 The smooth heat resistant sheet (see 12.9) is used for insulation and should be smooth and not warped. It is best to complete specimen assembly on the heat resistant sheet before placing it on the heating device. The sheet should be cooled and the wet wool should be dried between tests. This insulating material must be used, whether the bottom plate is heated or not, to prevent heat to or from the bottom of the test assembly.
12.4 In order to obtain the pressure per unit area 40±10g/cm 2 the total area of the wool flannel padding should bear a suitable rela- tionship to the mass of the plate pressing down on the padding. If the fabric to be tested has an appreciable thickness, it is necesary 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 speci- men size, the pressure depends on the design of the apparatus (ratio of mass and arca of top plate).
12.5 During the heating up period of the heating device and between the actual test pe- riods, both plates of the heating device should be in contact to insure a uniform distribution.
12.6 For less critical testing, 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 approximate ratio to exert a pressure of 40±10 g/cm 2. However, due to tempera- ture fluctuation during on-off differences over the iron surface, the accuracy and reproduc- ibility are limited. When a hand iron is used, it must be stated in the report.AATCC 133 pdf download.