Five Things You Could Do to Improve Your Color Consistency
Helping companies produce accurate, consistent color is a full-time job for Dillon Mooney. As our Technical Consultant for the Center for Technology and Research, Dillon, a 30-plus-year industry veteran, has encountered many of the challenges your company faces each day.
Here Dillon dishes five key improvements you can make today to get the consistent color your customers demand.
(Psssst! If you’ve ever called our Technical Hotline, you probably already know Dillon—he answers more than 1,500 inquiries a year!)
- The success of color management depends on consistency of the output devices. Once color management is implemented, it must be managed through process controls to maintain its repeatability. Run color bars on all jobs and include solid ink density patches, gray balance patches, 50% tint patches, and overprint patches to measure wet trapping. If you don't measure it, you cannot control it!
- Consider using under some Gray Component Replacement (GCR). These techniques remove some of the CMY that makes up the grays and add weight to the K separation. This makes it easier to control the color on press.
- To ensure your presses are printing consistently, first check that the solid ink densities are running at you shop’s standards. Additionally the tonal value increase (TVI or dot gain) values should be in an acceptable range.
Once you’ve created a color profile, it will only work if the press is printing with the same attributes. To monitor this, make sure to regularly measure the solid ink densities, TVI, gray balance, and wet trapping values. If different solid ink densities are run on different jobs, the ink film thickness differences can affect TVI, gray balance and wet trapping.
Slurring creates differences in TVI and will cause a shift in the color of a process image. Random slurring can cause the appearance of the color to change from sheet to sheet. A good slur indicator is the Ladder Bars on Printing Industries Test Forms. Star Targets included in our color bars will also detect slurring.
- Maintaining the consistency of the output of the press also involves standardizing consumables, including ink, plates, and fountain solution. Use process inks that are ISO 2846-1 compliant. ISO 2844-1 inks are going to have very similar hue and saturation levels, and are specified in the G-7 methodology.
Any time a different plate, blanket, fountain solution, or ink is used, check your process control aim points to ensure the press is printing the same way it was when the color management profile was created. Implement a preventive maintenance program that includes a good roller wash-up, deglazing, and roller setting procedure. For color management profiles to match your output, you need to address maintenance issues or face a gradual decline of press quality.
- Use ISO 3664 viewing standards. Colors can appear different under various lighting conditions—this is referred to as a “metamerism effect.”
ISO 3664 specifies a light source of D50, which is a 5,000 Kelvin spectrum, but has an expanded UV spectrum not available in standard 5,000 K bulbs. Perform critical color evolutions in a three-sided light booth (to block ambient room light) equipped with ISO 3664-compliant bulbs from a graphic arts viewing booth manufacturer. (Even a press console equipped with an overhead viewing light with ISO 3664 bulbs is probably not compliant due to ambient room light contamination.)
Printing Industries’ RHEM Light Indicator, is a three-color metamerism patch that will indicate if the light is 5,000 K. The indicators are useful in ISO 3664 viewing areas to show if ambient room light is contaminating the viewing spectrum.
Contact Dillon by clicking here or call the technical hotline at 800-910-4283 ext.786 (Members, please have your Printing Industries member number ready when you call.)