ISO Standard Inks can you help?

[Predisposed]

We are currently reviewing our ink supplier 'Stehlin' and looking to improve the quality of our print to achieve the 'best' ISO standard possible, any suggestions on Inks, we are testing Heidleberg(FLINT), Flint and Stehlins, all get close but on some the L.A.B values only just fall in.... ... anybody using Sun Chemical products?

[Lukas Engqvist]

only just fall in? In what way? Have you tested to see that you are at the right density? Is it primaries, secondaries or tertiaries that only just fall in?

[Predisposed]

Example (Flint Inks which gave us the best results)....
K deltaE 1.69
C detlaE 4.8
M deltaE 1.4
Y deltaE 2.0
Measured using Image control
Stehlin was much further out on the Magenta as well

Dot gain and speads all very close deltaE of 1.2
Really just interested in feedback about other Inks people are using to print to ISO standard, so that we can run trials on them.

[Lukas Engqvist]

Yes but deltaE just tells you how far you are off not in what direction?
Even the hue will vary with thickness. For example a Magenta may be more red the higher the density is, same may go for yellow etc.
What colours your secondaries is equally imoprtant. Too high densities may give low trapping (but both Magenta and Yellow being too red you would not notice in the red rather 100C 100Y being too cyan etc). And to low densities will give an unusually high trapping (wich means greens may be too yellow).

Measuring with just deltaE you can end up being mathematically "acceptable" but the result being wrong. I would suggest looking into the colourmanagement thread, where there is some discussions on the standards.

[Predisposed]

The densities we are printing are all spot on, hence the fact we are looking at different inks, the inks we currently use are not really capable of hitting ISO, some tests we did with epple inks where fantastic but where a bit costly, they came in with deltaE of less than 1.7 across the board, when printing to the correct densities.

[meddington]

An often overlooked aspect of the ISO 12647-2 standard in regards to solid CIElab values is that the contribution ofthe hue difference (delta H) shall not exceed 2.5. This helps to narrow the opening on the barn door that is the 5 delta E tolerance...though still is not perfect. Also important to keep an eye on the secondary overprint colors (some would argue more important, though ISO doesn't mandate). I personally would give a little on primaries for a gain on secondaries.

If compromise on the ink color is unavoidable, try to minimize the deltas on the important metrics. With Cyan and Yellow, b* is more critical, and with magenta, a* is more critical. Lowest delta E doesn't always win.

[Predisposed]

Thanks Mr Meddington we have found the same here, image control helps out alot, what I need to do though is find an INK which is similar to the epple ink; ie manufactured to a tight ISO standard, every batch is the same and every batch is designed to hit the LAB values (Overprints etc.) when printed. Its no good messing about on press with an INK to get it to come within the DeltaE required for ISO. When using the epple inks the results are gained without any problems... if only the cost was lower!

[jools68]

If the cost was lower you'd be "messing about on press with an INK to get it to come within the DeltaE required for ISO". You would not expect to pay VW prices and drive a Porsche?? It all comes down to what is commercially acceptable for your customers, would the majority of them be able to see the difference?

[keldrewett]

Originally Posted by jools68

If the cost was lower you'd be "messing about on press with an INK to get it to come within the DeltaE required for ISO". You would not expect to pay VW prices and drive a Porsche?? It all comes down to what is commercially acceptable for your customers, would the majority of them be able to see the difference?

Yep agree. It's all about quality V's economy.
I know which way I would be going....

[Predisposed]

I totally agree, given a chance I would probably use the epple inks, the difference in price would be nothing compared to the savings made due to quicker make-ready times, unfortunately there is only one supplier in the UK which seems to be scaring some people here off. Most of our customers do require ISO quality and do measure sheets, wether or not they can see a difference in quality doesn't seem to matter... its all about the numbers. Is anyone using Sun Chemical inks, they may be an option and we haven't looked at them yet.