Originally Posted by InfernalGuy
I am pretty sure works no matter what slot they are placed at
I forged my 1s LK comped staff with 3s uncomped, which was placed at secondary slot, and I got staff with 2 clean slots and 1 comped -.-
Your gear must be glitched. I managed to clean out my slots by putting a clean ring on primary and on secondary, 3s ring(Fully compounded).