i worked with a plasterer years ago who cleaned his tools every morning by throwing his bucket of trowels off the edge of the pool onto the floor he use to go through some trowels !!!!!:yikes:
We've always followed the 'hit it with the hammer' method and usually unscrewed from the drill!
However today I just bought a NEW paddle ( A Makita unit for £16-00) so the old one can go in the skip!
I mix my addy then clean & store the mixer ready for the next mix in a big old paint bucket, 18 inches deep with a few stones in the bottom. Mix the addy, a quick wash at pull pelt in the paint bucket.
Clean warm hands but still hit with a hammer ever 6 months or so to reduce the buildup.
Well, this might not be an over-night-method but put it into a bin with cheap vinegar acid.
As you know lots of bath room grouts are cracked if cleaned often with vinegar acid based cleaners, so this should work for the paddles too.
Regards, Martin