
I usually leave my singles on the bobbin at least overnight, which means when I ply a balanced yarn, it "acts" overplied, since the singles' twist set a bit while it rested on the bobbins. So, a soak in a warm sink will let everything relax back into the balanced state and I should get a balanced skein that I can simply hang to dry without weights.

If my plied skein isn't balanced, I'll weight it with as little as I can, so as not to remove the "bounce" from the yarn -- so I try a hand-towel, and only move up to a soup can if that doesn't work.
So, I always wash the skein and hang it, and put weight on it only if it's not behaving once it's had its warm bath.

For that one, I put it tightly around a niddy noddy and left it for a MONTH. Whew. Patience required for that one, and a "spare" niddy noddy. The twist is set, it's pretty, and it's art -- since I can't wash it! LOL. (washing would make the loops curl up on themselves, not the intended effect!)
(based on a post by me on Spin-List)