When I want a clean white background, I use a very simple approach.  Polar white paper, two strobes lighting the background, one on each side shot into an umbrella that shields the subjects from any direct light.  In this particular session, I set the background lights f/11.6.  Two subject lights were set to f/8.  The picture was taken at ISO 200, f/9, 1/125.  In post, I adjust the exposure upward in Aperture causing the background to drop to a very pure white and the exposure of the subjects to brighten to a very nice level without being over exposed.  You can see other examples from this session in my 'Recent Favorites'.