ISO 12571:2013 specifies two alternative methods for determining hygroscopic sorption properties of porous building materials and products:
a) using desiccators and weighing cups (desiccator method);
b) using a climatic chamber (climatic chamber method).
The desiccator method is the reference method.
ISO 12571:2013 does not specify the method for sampling.
The methods specified in ISO 12571:2013 can be used to determine the moisture content of a sample in equilibrium with air at a specific temperature and humidity.