Process and apparatus for testing bottles

1. Process for testing the thickness of a coating on a container, which comprises: providing a container having a carbon coating on the internal surface of the container; positioning means inside the container which shines ultraviolet light through the container; positioning at least one ultraviolet light sensor outside of the container and passing the ultraviolet light from the inside of the container through the container to the sensor; and determining the thickness of the coating by said at least one sensor which determines how much light passes through the container.

2. The process of claim 1 , wherein the container is a plastic container having an open mouth, an intermediate sidewall and a base adapted to support the container.

3. The process of claim 2 , wherein a rod is inserted inside the container which shines ultraviolet light through the container to said at least one sensor.

4. The process of claim 2 , including positioning at least two of said sensors outside of the container along the vertical length of the container.

5. The process of claim 2 , wherein said at least one sensor is movable along the vertical length of the container.

6. The process of claim 2 , wherein the container is rotated so that said at least one sensor is exposed to the entire circumference of the container.

7. The process of claim 2 , wherein said at least one sensor is connected to a meter which measures the amount of light passing through the coating.

8. The process of claim 2 , wherein the thickness of the carbon coating is from 0.01 to 20 microns, and the UV wave length is from 350 to 380 nanometers.

9. The process of claim 2 , including a lens over the sensor to focus the light passing through the container on the sensor.

10. The process of claim 2 , wherein the testing is associated with a carbon coating apparatus so that coating defects can be readily corrected.

11. Apparatus for testing the thickness of a coating on a container, which comprises: a container having a carbon coating on the internal surface of the container; means inside the container which shines ultraviolet light through the container; at least one ultraviolet light sensor outside of the container, wherein said ultraviolet light passes from the inside of the container through the container to the sensor; wherein said sensor is operative to determine how much light passes through the container, thereby determining the thickness of the coating.

12. Apparatus according to claim 11 , wherein the container is a plastic container having an open mouth, an intermediate sidewall and a base adapted to support the container.

13. Apparatus according to claim 12 , including a rod inside the container which shines ultraviolet light through the container to said at least one sensor.

14. Apparatus according to claim 12 , including at least two of said sensors outside of the container along the vertical length of the container.

15. Apparatus according to claim 12 , wherein said at least one sensor is movable along the vertical length of the container.

16. Apparatus according to claim 12 , including means to rotate the container so that said at least one sensor is exposed to the entire circumference of the container.

17. Apparatus according to claim 12 , including a meter connected to said at least one sensor which measures the amount of light passing through the container.

18. Apparatus according to claim 12 , wherein the thickness of the carbon coating is from 0.01 to 20 microns and the UV wave length is from 350 to 380 nanometers.

19. Apparatus according to claim 12 , including a lens over the sensor to focus the light passing through the container on the sensor.

20. Apparatus according to claim 12 , including an associated carbon coating apparatus so that coating defects can be readily corrected.