Dark Blonde Girl With The Ironing Board At Home

Another source suggests slightly higher temperatures, for example, 180-220 °C for cotton
Chemistry
When the fabric is heated, the molecules are more easily reoriented. In the case of cotton fibres, which are derivatives of cellulose, the hydroxyl groups that crosslink the cellulose polymer chains are reformed at high temperatures, and become somewhat "locked in place" upon cooling the item. In permanent press pressed clothes, chemical agents such as dimethylol ethylene urea are added as crosslinking agents.