Checkerboards

I feel like I'm in an old laundry commercial - How do I get the blacks "black" and the whites "white", all while preserving decent skintones in the middle?  These were shot at South Sound Photo Studio, where I had access to all sorts of lighting equipment.  I set up two strobes to blast the background, but it was really tricky to avoid too many reflections off the Home Depot linoleum being used as the seamless backdrop.  Messing with curves in photoshop was necessary to get things as distinct as possible (mainly dragging the top right point further to the left along the top of the box).  I'm pretty happy with the results, but still feel I have some learning to do in this area.