The present invention relates to curable coating compositions containing acetoacetylated polyvinyl polymers obtained from polyvinyl polymers, such as polyvinyl butyrals. In one embodiment, the invention includes mixing spent catalyst from a reactor and cold catalyst from a catalyst cooler in a mixing zone and directing the mixed catalyst to the regeneration zone in a fluidized manner with a fluidizing medium. The tapered ridge bends when it contacts a surface, whereupon the radius of curvature of the ridge increases monotonically with increasing shear load. The other end of the drive shaft extends through the housing to a cam, located with a distal end of the drive shaft housing. The optical coupling element is positioned so that its input end is substantially proximate with the second focal point of the secondary reflector.