What`s the ink density reference of commercial web printing?

[gordo]

Density is an indirect measure of ink film thickness that comes with a number of assumptions. Looking for a particular color is much more specific.

I agree.

Second problem comes when you say, "…achieve the appropriate +/- densities. At that point the hues of your primaries and secondaries should be within the tolerances of the hues of the target you are trying to achieve.…" The key words there are should be. And what if they're not?

When a printer is trying to align their process to an industry specification or standard then, IMHO, they should involve their suppliers to help them chart the path to that destination. In that context when they achieve the appropriate +/- densities they should be hitting the desired Lab targets. Changing SIDs may or may not enable them to hit the desired Lab values and if they are only aiming for a specific Lab value they might compromise their press stability and integrity. If they don't hit the desired Lab values at the correct densities then it falls to their ink supplier to adjust the inks or change ink series so that the goals are met.

Changing inks is not a small undertaking.

Correct. That is why it should be undertaken with the guidance and assistance of the ink supplier. But the fact that changing inks is not a small undertaking does not validate a method that starts with running a press in such a way that hitting Lab values is the sole goal. Hitting Lab values is, IMHO, not a methodology for defining SIDs - i.e. ink film thickness since Lab values describe color not ink film thickness. Conversely ink film thickness - solid ink density - is not a methodology for defining color.

The standard for process ink color and transparency is ISO 2846. ISO 2846 conditions are not at all similar to running on a press. And not all process ink sets are ISO 2846 compliant.

Like I said, bring the ink supplier into the equation. Establish the goals.

Everyone on this thread assumes that I'm talking about running the inks at higher densities.

I'm not.

I'm talking about identifying specific color targets and finding out what you would have to do to achieve those targets.

I agree.

I've found that I generally have move my primary colors to hit the secondaries. Looking at specific color targets lets me find those compromises.

I agree. But a press is not an inkjet printer. It is a substrate coater. All of the design and engineering of a press and its controls, for better or worse, are there to coat a substrate with a liquid film as effectively, efficiently, accurately , and consistently as possible. The needs of coating a substrate with ink and water under pressure (which don't exist with an inkjet printer) need to be met or you will have compromised press production.
You need the two components (SIDs and Lab) together to make the process optimal. And when I say SIDs I guess I'm including a lot of things that are required to achieve a good coating of ink on the substrate.
When the coating is optimal the press condition is optimal irrespective of the ink hues. If the correct inks have been selected for the targets that have been identified then you should be hitting those Lab values, because if you don't you cannot hit your target for color. And if those Lab values are not achieved then altering the coating conditions of the press may destabilize the press resulting in presswork problems.

best, gordo

 

[Deleted member 16349]

The press just prints structures of ink. Solids, overprints and screens. These structures of inks are filters of light.

If these structures can be printed consistently and predictably, then one can apply a colour management method.

The foundation of the printing of these structures is the ink film (ink content of the ink film) that results in the SIDs. Trying to get the specific SIDs to be a certain Lab values is pointless in my opinion.

Once a set of SIDs is chosen, that will determine the whole range of structures that can be printed for a set of inks, paper and screens. This then determines the gamut of what can be printed.

Trying to make this whole system print to some kind of standard is probably a fruitless effort. Just let it print the way it will print and map it.

Of course that is my view and that may not fit with how things are done. As usual.

 

[rich apollo]

Gordo, Erik,
I suppose we will have to agree to disagree.

 

[meddington]

I think there's quite a bit more latitude in adjusting ink densities to meet hue requirements than is being implied.

 

[BeauchampT]

Cynicism in the print trade? Impossible! ;-)

You're assuming that increasing the SIDs will get you to your target Lab values - which may not be the case depending on the ink hue set you're working with. I.e. the particular hue of magenta, cyan, and yellow (and somewhat black) that you're using.

best, gordo

True enough. For the paritcular ink set we run, our ink doesn't turn hue until quite a high denisty, so we can push our densities a little.

However, after reading everyone's comments..I have a lot more useful information to appraoch my management and ink supplier with. Very helpful. Thanks.

 

[Greg Imhoff]

This topic appears well examined if not well worn. This may be more useful if (re)created, into a new thread. This is important but may be running a bit deep with 4 or more pages. Good stuff crowding into one space often becomes unread. Greg

True enough. For the paritcular ink set we run, our ink doesn't turn hue until quite a high denisty, so we can push our densities a little.

However, after reading everyone's comments..I have a lot more useful information to appraoch my management and ink supplier with. Very helpful. Thanks.