|Ink is Only a Fraction of Offset Costs|
1. High Dot Gain
Ink is not the only factor to consider in this case. There are many other factors to consider relating to your plates, pressure settings and chemistry. Let's just consider a couple possibilities that may involve the ink itself that is causing high dot gain.
- Cause: Ink viscosity too low. Solution: Consult your ink manufacturer and request change. Increasing your viscosity may make an improvement, but cause problems in other areas. Ask your supplier for help to understand all the underlying issues.
- Cause: Improper ink and water balance. Solution: Run minimum water and the minimum ink to achieve proper density. It may be that you are not able to be within a proper ink and water balance window due to the inks properties. Ask your ink manufacturer for a certificate of analysis and pay attention to values that indicate such things as water pickup.
Again, let's just look at the factors relating to ink. Piling occurs on all offset printing presses, but can be controlled. A good quality offset printing ink will cause minimal piling. Here are some possibilities that can cause piling that relate to ink.
- Cause: Poor ink and water balance. Solution: In this case, running the absolute minimum water is not always the best solution to this problem. Anti piling agents are added to fountain solution to control it. You may consider running your water just above minimum and see how the ink reacts. Consider too that often paper is the culprit, so you must examine the piling itself to be certain where it's coming from. As well, consult your offset printing ink manufacturer to discuss the quality of the ink. Here is a recent problem troubleshooting piling that I had.
When troubleshooting setoff problems, understanding the problem requires a thorough understanding of the drying process. With heatset printing, the flash point of the ink will have a large bearing on whether it dries properly. In coldset printing where most drying takes place through absorption and evaporation, setoff is much more prevalent and in some cases may be unavoidable. Here are some causes of setoff that relate to the ink itself.
- Cause: Poor ink strength. Solution: Get a higher pigment strength in your ink to run a lower ink film thickness. This is especially important in coldset printing. Setoff cannot be completely eliminated in this case, but sharper points on the grater rollers and keeping nips away from image area may help alleviate the problem. With heatset inks, ensure that oven temp and cooling is sufficient. Quite often more heat does not make the problem better, but worse. Cooling is more often a key factor in ensuring that inks set properly.
|Ink Density Plays A Major Role|
- Cause: Densities set too high. Solution: Run only the necessary density. Quite often with black, a pressman will run higher than normal to make the print nice and dark. Do not expect good ink mileage if this is your procedure. It is neither good cost wise, nor is it a proper way to get good quality.
- Cause: Penetration into paper is too rapid. Solution: Besides changing paper, perhaps the ink supplier can provide an ink with more hold out.
- Cause: Poor ink and water balance. Solution: Run a minimal amount of water and you will see better results in your ink mileage.
- Cause: Low pigment strength. Solution: Again, your ink manufacturer should see you have a good quality ink that has proper pigment strength.
Here are some more problems associated with ink. Click on the link for further details on how to troubleshoot them.
These are of course just a few problems that can be cause by ink. Troubleshooting offset printing ink requires and understanding of the full gamut and you should not be quick to lay the blame on the ink right away.
Offset Printing Troubleshooting Guide