system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 Why do towels/linens get stiff when left to air dry but are fluffy when put in a laundry dryer?

I noticed that my wash cloth in the shower will get stiff when it air dries and realized other things seem to do the same. I’m guessing it has to do with the heat and/or motion?
gpt
Motion. It's more noticeable in hard water areas.

If you air dry, a small quantity of dissolved minerals will be left coat the fibers. Like a water stain. It makes the fibers stiff until it breaks off.

In a drier, because the fabric is always in motion, the mineral deposits dont get a chance to build up.