Hickeys in Printing are Nothing Romantic
Hickeys in Printing Suck
In high school you may be familiar with the term “hickey”. If you are a female perhaps turtle neck sweaters come to mind or excuses like a curling iron burn. For guys in was a symbol of passion with a desired school hotty. Sometimes you would hide them from people while other people (certain friends) would see them as a form of a trophy. In printing, the term “hickey” is not associated with anything pleasant.
Hickeys in printing inks are caused by material which is carried by the ink and are not particles which originate from the paper.
Possible sources of hickeys are pieces of skin from inks, uncooked resin in the ink or roller fragments from a dry or deteriorating rubber ink roller, skin, for example, will adhere to the plate and will reject water, but accept printing inks . Because of its thickness, the particle will be inked by the form roller(s) but it will prevent inks from contacting the plate in the surrounding area (Figure 1). This “ring” around the particle will not print, creating the characteristic “donut” affect. (Figures 2 and 3)
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1 Example of how ink skin, adhering to the plate, prevents the ink from reaching the image in the surrounding area, creating the characteristic”donut” affect. |
 Look at the skin adhering to the plate. |
| 2 How a hickey would look through a printer’s loupe. | |
| 3. The characteristic “donut” affect. |
4. Hickeys on form rollers through a printer’s loupe.
How hickeys manifest themselves
5. Taking a tape pull from the ink form roller.
6. Ink hickeys on the plate through a printer’s loupe.
7. Taking a tape pull from the plate.
In order for a complete analysis to be done, the particle causing the speck must be removed from the press. For example, tape pull material can be pressed onto the ink former and the contaminate removed. (Figures 4 and 5)
The material on the tape can then be photographed and tested to determine its origin (Examples on pages 6 and 7).
Similar procedures can be used (Figures 6 and 7) to remove the material causing the ink hickey from the plate.
If the material causing the specks is in the ink, the only possible solution is to remove the ink from the fountain and try a different batch. Caution: A clean-up of the ink system may not remove a/link hickeys. If the problem persists, form rollers may have to be removed, cleaned and checked for possible roller deterioration.
Visual Analysis of Tape Pulls of Ink Hickey Materials
Tape Pulls For Analysis
Magnified view of resin chip.
| 8. Tape pull of ink skin. | 11. Photomicrograph of ink skin. |
| 9. Tape pull of rubber roller fragment. | 12. Photomicrograph of roller fragment. |
| 10. Tape pull of uncooked ink resin chips. | 13. Photomicrograph of resin chip. |
Tape pulls of the materials that may cause ink hickeys will be examined and analyzed in various ways. The photos to the far left are examples of how some materials appear on the tape pull. The corresponding photomicrographs to the right show the particle as it would appear under a Scanning Electron Microscope (S.E.M.). Further analysis can determine chemical content. 14. Chemical analysis of a rubber roller Above is an example of a chemical analysis of a rubber roller fragment indicating the presence of S (Sulfur) and Cl (Chlorine). Note how this analysis differs from that of paper coating materials on page 9.
If you suspect that your printing has hickeys, be sure to speak with your printer as soon as possible to find out the best ways to correct the problem. There are several options you can take advantage of, the first one is to make it known that you can identify with the technical terms describing this printing blunder.
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