Lightweight preform and method of manufacture

1. A preform for use in blow molding a plastic container, the preform comprising:

a body having an open end and closed end, the body being adapted to form a body of the container when the container is blow molded;

a finish having a top surface, an inner wall having circumferentially-spaced thin segments alternating with thick segments, an outer wall and a boundary portion formed between the thin segments and the thick segments;

wherein the thin segments exist entirely in the finish and extend towards the open end of the body of the preform, wherein the thick segments do not extend to the top surface and further wherein the boundary portions exist entirely in the finish;

and

further wherein the thick segments are substantially the same width as the thin segments.

2. The preform of claim 1 wherein the thin segments have a radial thickness of about 0.050 to about 0.100 inch.

3. The preform of claim 1 , wherein the thin segments have a radial thickness of about 0.060 to about 0.090 inch.

4. The preform of claim 1 , wherein the thin segments have a height that is less than or equal to a height of the finish.

5. The preform of claim 4 , wherein the height of the thin segments is less than or equal to approximately 1 inch.

6. The preform of claim 1 , wherein the thin segments are rectangular-shaped.

7. The preform of claim 6 , wherein the thin segments have the same height.

8. The preform of claim 1 , wherein the thick segments further comprise a surface for contacting a molding tool.

9. A preform for use in blow molding a plastic container, the preform comprising

a body adapted to form a body of the container when the container is blow molded; and

a finish having a top surface, an inner wall with circumferentially-spaced, alternating raised portions and non-raised portions, an outer wall and a boundary portion formed between the raised portions and the non-raised portions;

wherein the non-raised portions exist entirely in the finish and do not extend into the body of the preform, wherein the raised portions do not extend to the top surface and further wherein the boundary portions exist entirely in the finish; and

further wherein the raised portions are substantially the same width as the non-raised portions.

10. The preform of claim 9 , wherein the raised portions have a radial thickness of about 0.090 inch to about 0.125 inch.

11. The preform of the claim 9 , wherein the raised portions further comprise a surface for contacting a molding tool.

12. The preform of claim 9 , wherein the raised portions further comprise ribs.

13. The preform of claim 9 , wherein the raised portions further comprise protrusions.

14. A preform for use in blow-molding, the preform comprising

a top surface; and

a finish having an inner and an outer wall, the inner wall having circumferentially-spaced alternating thick and thin segments; a boundary portion formed between the thick segments and the thin segments;

wherein the thin segments extend along but not beyond the finish, wherein the thick segments do not meet the top surface and further wherein the boundary portions exist entirely in the finish; and

further wherein the thick segments are substantially the same width as the thin segments.

15. The preform of claim 14 , wherein the thin segments have a radial thickness of about 0.050 to about 0.1000 inch.

16. The preform of claim 14 , wherein the thin segments have a radial thickness of about 0.060 to about 0.90 inch.

17. The preform of claim 14 , wherein the thick segments have a surface for contacting a molding tool.

18. The preform of claim 14 , wherein the thin segments have a height that is less than or equal to a height of the finish.

19. A method of manufacturing a blow-molding container comprising

providing the preform of claim 1 , and

blow molding the preform to form a container.

20. The method of claim 19 , wherein the step of providing includes manufacturing the preform.