This may sound stupid, but I am having a difficult time getting paint rollers clean. I am painting the bedrooms in my home, and am using 3/8' nap rollers with very rigid cardboard cores. I bought a little tool that helps clean brushers & rollers, and it works great on the brushes, and SEEMS to work on the rollers. I am using Benjamin Moore latex paint, and no matter how clean I think I have gotten it, after the roller has had a chance to dry, the nap is no longer soft, but rather a little crusty. I can't see the paint on the cleaned rollers, but I am assuming there must be some residue for the roller to feel a little stiff. Should I expect the roller to regain its softness when I begin using it again, or should I just throw them away after each use?