system
Given the following post, respond as if you're commenting on Reddit:
human
How come when you wet a piece of paper and then let it dry it gets all crinkled and makes a crinkly noise when folded?

So I was messing with some watercolors and the paper was getting all stiff and crinkled after I’d finish wetting it, I know that’s just what happens when you wet the paper but why does it happen, is it just setting the paper and setting it into place crinkled or Is something else happening with the water and paper? I have no clue if it’s physical or chemical why this happens.
gpt
The water causes the fibers in the paper to expand. As the expand the individual fibers bend and twist against each other. When the paper dries the fibers shrink back down, but friction between fibers holds them somewhat in place. As a result of the expanding and shrinking the positions of individual fibers is changed so the paper ripples and warps to essentially even out the tension amongst all the fibers.

You can mechanically release some of the tension by smoothing out the now dry paper. You will probably be able to get rid of some of the wrinkles because you are basically pulling the fibers into different positions, but you wont get back to the smooth pre-wet condition because some of the fibers are now kinked, broken or otherwise damaged.