Why do we need to sprinkle water on cotton clothes before ironing/pressing them? Many a times, cotton garments need water to be sprinkled upon them before pressing or ironing. Without water, these clothes cannot be properly pressed by a hot iron. Steam iron can be used as an alternative. But some type of moisture is needed, otherwise the garments remain shrivelled. Why?
 A: I quote the answer by Wrichik Basu. But I add that ironing has to do, rather than with hydrolysis of fibers as suggested in comments (lifetime of items would be very short) with the breaking of H bonds.
Is very similar to hair dressing.
The use of water has the effect of "hydrolisying" such H bonds in addition to enhance thermal conduction to supply energy for the above breaking of bonds.
A: The main reason (according to me) is that, cotton is a bad conductor of heat. As a result, the heat from the iron does not get evenly distributed throughout the fabric. So, some parts of the fabric get the heat, while other parts do not, which is why they remain shrivelled.
Sprinkling water on the clothes causes absorption of these molecules of water in between the strands of fabric (aided by capillary action and the cohesive nature of water). When heat is applied, the molecules of water absorb this heat and evenly distributed them throughout the fabric. Thus, the clothes can be properly pressed.
Steam ejected from steam iron does the same thing, but in a different way. In case of water, the water absorbs the heat and evenly distributes it throughout the material. But steam is itself heated. The hot gas is forced through the fabric, which distributes heat throughout the cloth.
This is my explanation. Anyone who has a different explanation can freely put in their opinions as additional answers.
