Download a PDF version of this page.

Technical Bulletin 13-12/87

Scan plates to significantly reduce 4-color press make-ready time by accurately setting the ink keys prior to printing.

How Does it Work?

The scanner moves across the surface of a plate and records "image information" from the plate onto a magnetic card or tape. The magnetic card or tape is put into a control console for a particular press and the "image information" is used to adjust the ink keys prior to printing.

Requirements for Scanning

1. Careful plate handling: no kinks, bends, abrasion marks, fingerprints, writing, etc.

2. If a yellowish cast is observed on the plate, either post expose the plates to reduce the coloration or don't post expose and keep the plates covered until ready to scan.

3. Calibration plates should be made whenever run numbers change or where complaints are heard from the pressroom; i.e., excessive manual adjustment of the key setting.

4. Maintain consistent plate orientation throughout the imaging, plate processing and scanning process; i.e., keep the top of the plate at the top of the vacuum frame, left side of the processor and top of the scanner. Grain direction and orientation can affect scan accuracy.

5. Scanner calibration patches should always be used for scan accuracy.

6. Accurate positioning of scan patches is critical for scan accuracy.

7. Keep calibration reference strips spotless to ensure scan accuracy.

8. Scanners are about 80% accurate for ink key settings.

9. Keep plates flat when scanning - if plate curl exists, tape the plate down to
improve scanner performance.

10. Where required, ensure the plate grain direction is correct. Order plates with the grain direction around the cylinder for improved scan accuracy.

11. Most scanners require each type of plate be calibrated before scanning.

12. "Key scanner operators" will improve consistency; instructions are sometimes confusing and machines can be complicated.

13. Keep the scanner in a dust-free computer type environment.

Scanners are extremely delicate and require considerable operator skill. They are required to read the finest screen tints and type. The more care in using, the better the results.

Copyright 1996 Imation. All rights reserved.