Joe, I think I can tell you why you feel the photo's weren't as good as you liked. The lighting is uneven.
My guess is that you had only one light to light the blanks. The Inverse Square Law is affecting your pics. Basically, the law goes on to explain how light falls off the further away you are from the source. The reason that your white background has a gradient is because the light is falling off from the source. You could look at adding a seperate light to evenly light the background and another light to light the blank.
If your camera has the ability to use Spot Metering, that could also help. It could help the camera to not average all of exposure and affect the picture.
Hopt this helps some.