Basecoat and associated paperboard structure including a pigment blend of hyper-platy clay and calcined clay

1. A basecoat comprising a pigment blend including a calcined clay component and a hyper-platy clay component, wherein said hyper-platy clay component has a shape factor of at least about 40:1, and wherein said pigment blend has a sediment void volume of at least about 50 percent when measured by a technique involving diluting said pigment blend with water to 50% by weight solids, centrifuging a 70 gram sample of the resulting slurry at 8000 g for 90 minutes and calculating the volume of water remaining in the voids of the sediment after pouring off and weighing the supernatant liquid.

2. The basecoat of claim 1 wherein said shape factor of said hyper-platy clay component is at least about 70:1.

3. The basecoat of claim 1 wherein said shape factor of said hyper-platy clay component is at least about 90:1.

4. The basecoat of claim 1 wherein said calcined clay component comprises at least about 10 percent by weight of said pigment blend and at most about 60 percent by weight of said pigment blend.

5. The basecoat of claim 1 wherein said calcined clay component comprises at least about 15 percent by weight of said pigment blend and at most about 40 percent by weight of said pigment blend.

6. The basecoat of claim 1 wherein said pigment blend consists essentially of said hyper-platy clay component and said calcined clay component.

7. The basecoat of claim 1 further comprising a carrier, wherein said pigment blend is dispersed in said carrier to form a slurry.

8. The basecoat of claim 1 wherein said sediment void volume is at least about 55 percent.

9. The basecoat of claim 1 wherein said sediment void volume is at least about 60 percent.

10. The basecoat of claim 1 wherein said calcined clay component comprises calcined clay particles, and wherein at most about 90 percent of said calcined clay particles are less than 2 microns in diameter.

11. The basecoat of claim 1 wherein said calcined clay component comprises calcined clay particles, and wherein at most about 75 percent of said calcined clay particles are less than 2 microns in diameter.

12. The basecoat of claim 1 wherein said calcined clay component comprises calcined clay particles, and wherein at most about 60 percent of said calcined clay particles are less than 2 microns in diameter.

13. The basecoat of claim 1 wherein at least one of said calcined clay component and said hyper-platy clay component comprises kaolin.