The moisture regain of textile materials varies with time and its weight is also different. In order to eliminate the weight difference caused by different moisture regain and meet the needs of textile materials trade and inspection, the state has stipulated corresponding standards for moisture regain of various textile materials, which are called public moisture regain. It is close to the equilibrium moisture regain measured at standard temperature and humidity.

It should be noted that the regulations on the open moisture regain of textile materials in various countries are often determined according to their own actual conditions, so they are not completely consistent.