Insulated cooking vessel

1. A method of forming a cooking vessel, the method comprising the steps of:

a) providing a first vessel having a bottom surface surrounded by substantially upright walls which comprises an outer shell and an inner lining, the first vessel having a first portion and a second portion, the first portion being the portion thereof in which the inner lining covers an interior bottom surface of the outer shell and extends only partially upward along an interior of the outer shell and the interior of the bottom surface, the second portion being the unlined upper extent of the outer shell that is beyond the first portion,

b) drawing the first vessel to reverse the inner lining to surround an exterior of the outer shell in the first portion to form a cooking vessel wherein the second portion of the outer shell first extends circumferentially outward from the inner lining and then downward, being substantially parallel to the first portion to provide an outer wall whereby a gap is formed between the outer wall formed from the second portion and an inner wall formed from the first portion, wherein the inner lining faces the gap,

c) attaching a lower extent of the second portion to the bottom of the cooking vessel thereby sealing the gap formed between the first and second portions.

2. A method of forming a cooking vessel according to claim 1 further comprising the step of attaching a first metal cap to the bottom of the cooking vessel wherein the lower extent of the second portion of the cooking vessel is attached to the first metal cap.

3. A method of forming a cooking vessel according to claim 2 further comprising the step of attaching a second metal cap to the first metal cap at the bottom of the cooking vessel wherein the lower extent of the second portion of the cooking vessel is bonded between the first and second metal caps.

4. A method of forming a cooking vessel according to claim 3 wherein the first metal cap comprises aluminum or an alloy thereof and said step of the attaching the lower extent of the second portion to the bottom of the cooking vessel comprises impact bonding to extrude at least a portion of the aluminum first metal cap into the lower portion of the gap adjacent the first metal cap.

5. A method of forming a cooking vessel according to claim 3 wherein the first metal cap conforms to the exterior bottom before attachment thereto and the second metal cap is deformed.

6. A method of forming a cooking vessel according to claim 3 wherein the second metal cap is copper and the first metal cap is aluminum.

7. A method of forming a cooking vessel according to claim 3 wherein the first metal cap is spot welded to the exterior bottom of the cooking vessel before impact bonding.

8. A method of forming a cooking vessel, the method comprising the steps of:

a) providing a first vessel having a bottom with an interior and an exterior surface surround by substantially upright surrounding walls,

b) drawing a portion of the bottom upward into an interior region between the substantially upright surrounding walls to invert at least about half the height of the surrounding walls so that the interior bottom surface becomes the interior bottom surface of a second cooking vessel, the second vessel having a substantially parallel interior and external walls connected at an upper rim of the second vessel to provide a circumferential gap there between,

c) sealing the gap formed between the interior and exterior walls thereof.

9. A method of forming a cooking vessel according to claim 8 wherein said step of sealing the gap comprises attaching a lower extent of the exterior wall to the exterior bottom of the second cooking vessel.

10. A method of forming a cooking vessel according to claim 8 wherein said step of sealing the gap comprises attaching a first metal cap to the bottom of the second cooking vessel wherein a lower extent of the second portion of the second cooking vessel is attached to the first metal cap.

11. A method of forming a cooking vessel according to claim 8 wherein the first vessel has a laminated construction wherein the interior bottom surface is a first material and the exterior bottom surface is a more thermally conductive material than the first material.

12. A method of forming a cooking vessel according to claim 10 further comprising the step of attaching a second metal cap to the first metal cap at the bottom of the second cooking vessel wherein the lower extent of the second portion of the second cooking vessel is bonded between the first and second metal cap.

13. A method of forming a cooking vessel according to claim 10 wherein the first metal cap is spot welded to the exterior bottom of the second cooking vessel before impact bonding.

14. A method of forming a cooking vessel according to claim 10 wherein the first metal cap is a ferromagnetic material.

15. A method of forming a cooking vessel according to claim 10 wherein the first vessel has a laminated construction wherein the interior bottom surface is a first material and the exterior bottom surface is a more thermally conductive material than the first material.

16. A method of forming a cooking vessel according to claim 12 wherein the first metal cap conforms to the exterior bottom before attachment thereto and the second metal cap is deformed.

17. A method of forming a cooking vessel according to claim 12 wherein the second metal cap is copper and the first metal cap is aluminum.

18. A method of forming a cooking vessel according to claim 12 wherein the first metal cap is a ferromagnetic material.

19. A method of forming a cooking vessel according to claim 12 wherein at least one of the first and second metal caps is selected from the group consisting of copper and aluminum.

20. A method of forming a cooking vessel according to claim 11 wherein the first material is stainless steel and the more thermally conductive material comprises one or more layers of at least one of copper and aluminum.