For colour matching inks with several colours are mixed. With the help of an IGT printability tester a solid print is made under standard conditions and the print is compared to an original print or design visually or with a spectrophotometer. When the original print is printed in a screening it is difficult to compare a solid print of the printability tester to this screened original. For that reason there is a printing form with a photopolymer of 40 l/cm (100 l/inch) with printed areas of about 15, 35, 65 and 85 % to print on a smooth substrate. This method is used for paste inks.

Principle

The screened printing disc is inked on an IGT inking unit with the ink to be tested. A print is made on a substrate (most of the times paper) under standard conditions with an IGT printability tester of the type Global Standard Tester. The colour of the screened print is compared to the original print or design.

Method of operation

• It is recommended to execute the test in the standard atmosphere; to most standards it is 23.0 ± 1.0 °C (73.4 ± 1.8 °F) and 50 ± 2% rh. • For the operation of the AIC2-5T2000, Global Standard Tester, High Speed Inking Unit 4 and ink pipette follow the instructions of the manuals, IGT information leaflet W100 and the displays accurately. • Handle the samples carefully.

Assessment

1. Apply 0.10 cm³ of the mixed ink (for rough papers this volume can be more) to the inking unit and distribute the ink. 2. Place the printing disc on the printing disc shaft of the inking unit and ink the disc during the preset time. 3. Mount a test strip on the sector of the printability tester. 4. Remove the disc from the inking unit and place it on the (top) shaft of the printability tester. 5. Turn the disc so that the seam of the disc is just below the contact area between the disc and the sector 6. Make a print. See W100. 7. Take off the printed strip from the sector 8. Examine the printed strip visually and compare it to the original print. 9. Remove the printing disc from the tester and clean it with the rags and naphtha. 10. Clean the rollers of the inking unit or use the next segment for the following test. 11. Repeat the points 1 thru 10 for the next test. It is recommended to perform the test at least two times 12. After finishing the tests clean and store all parts as described in the manuals. 13. Make an accurate record of the conditions and the results of the test.