You have way more light then me. The key to getting the background pure white is that you need to get light behind the object that is brighter then the light hitting the object itself.
It's near impossible if you are doing this with only lights from the front unless you have barndoors or a setup to control the light direction and keep it off the object itself as whatever light you are shooting will be lighting the object and the background at the same exposure level so you will need to overexpose the object to get a white background.
Right! totally agree. I have 10 CFL's in the 2 clouds and 2 4ft tubes focused on the backdrop. I get a pretty reasonable white background....not perfectly white. But even though I want that, I think the next step would be offsetting the backdrop from the wall 6" or so and using a flash/synchro. That would take me a while to figure out and just not sure its worth it for me.
On a semi-related note, I got a nice message from a buyer today. I'm sure he tells this to all the sellers.
"I wish to extend my sincere compliments to whomever took the time to document AND photograph this Brioni suit in such amazing detail. On a scale of 1-10 it is an 11. Better than any other suit presentation I have seen on eBay.
Surely some hyperbole there, but still appreciated.