1.1 The purpose of this standard is to specify four conventional methods for the determination of the mass of water absorbed by a plastic specimen of defined dimensions, which is immersed in water, for a time, at a specified temperature. Two of the methods are used when it is desired to take into account the possible presence of water-soluble matter. 1.2 The four conventional methods specified can be applied to all plastics, except cellular plastics and those that soften at the temperature of boiling water, to the extent of causing total loss of their shape. In the latter case, only the tests can be applied at 23 °C. 1.3 Standard immersion periods are 24 h at 23 °C and 30 min at the boiling point of water, but other test conditions can be agreed. NOTE- Except for the mass variations covered by this standard, the influence of water absorption on the properties of plastics will be determined in accordance with the UNE 53-029 standard.