The background that this bag sits on is a white translucent piece of plastic. I've used 4 lights: one behind to shine through the plastic, two side lights and a on-camera flash. How can I get the background White? All suggestions appreciated! The gray boxes were intentional to block out the company name.

Fabulous feedback! Thanks for all the replies!

I have been trying to photograph food coloring while it disperses in a large clear vase of water. It's proving to be quite difficult! Any suggestions would be great. So far, I've tried to put the food coloring close to the edge of the vase to reduce the magnification of the water and get more of the moving food coloring in focus. I've also focused on an object placed in the vase before adding the food coloring. Overall, I'm not happy with the results - too much of the image is not in focus. The movement and magnification from the water and glass vase seem to be a combination of factors I need help with. Thoughts?