I've heard of the glitch where they don't work whilst in a Cellar, but does this also happen inside a cave?
Also what calculates a Tub's QL? The boars and your Carp.? On the wiki it says something about the quality of the leather, but it doesn't take leather to make it...
And does the amount of Water and the Bark in the tub affect how long the process takes, or is it no different?