Standard ink densities?

Gregg

Well-known member
Just received a third party process swatch book. In the book it lists the densities that the job was run at. They are:

K: 1.90
C: 1.45
M: 1.50
Y: 0.95

Are these standard numbers? If not, what are standard numbers, or is this simply to vague of a question?

To be honest I know little on this topic.
 
Re: Standard ink densities?

If you look at page 21, Section 6.2, of "G7_how-to_v6[final]" freely downoadable from www.gracol.org, although solids are to be run to Lab aim values, approximate Status T densities are listed:
C 1.45 +/- 0.10
M 1.45 +/- 0.10
Y 1.0 +/- 0.07
K 1.7 + 0.2 - 0.05

So the densities you listed are within that tolerance. Next would be to check TVI, but since TVI is obtained from colorimetry in GRACoL2006_Coated1, then the TVI values are gonna be different than TVI obtained from densitometry. To get TVI values obtained from densitometry, you'll need to purchase ISO 12647-2. Note: Solids for GRACoL2006_Coated1 are the same as ISO 12647-2 solid Lab values.

Don
 
Re: Standard ink densities?

Thanks, Don.

I must admit, alot of what you mention is over my head. I have no idea what TVI is, but I am in the process of printing that Gracol doc you mention and will have a read.

Thanks again.
 
Re: Standard ink densities?

TVI is the dot gain. It is irrelevant for measuring total ink density on a solid swatch. The numbers from Gracol are the results from their given ink and paper. I found that all of these recommended densities worked except cyan which was closer at a density of 138. This was based on Kohl-Madden Spectrum series ink on Sterling Ultra stock. The way for a printer to determine the printing density is run a variety of densities and take lab readings using a densitometer. The density that comes closest to the target is what you should run to. This will vary by ink and paper combination.

If you are refering to the Pantone swatch guides that list the densities that the book was created with, I would be skeptical. Take an actual reading of the book with your densitometer and will find that these numbers will vary greatly. Of the course the designer that is thinking the swatch book is blessed by God himself doesn't understand all of this.
 
Re: Standard ink densities?

The values you have mentioned are what we use for coated paper.
Does anyone have the values for uncoated paper??
We use
C-110
M-110
Y-95
K-130
 
Re: Standard ink densities?

The standard ISO 12647-2 does not define valuables of density. Only Lab. defines values
It is necessary to accomplish a test of inky to define correct the values of density at each workshop. These varied in terms of ink, the paper, etc ...

Pardon for my very bad English.
 
Re: Standard ink densities?

Hi Gregg,

IMHO, your standard densities can be can be of any value. As long as it gives you a color gamut that is big (hopefully bigger than ISO 12647-2) and that it is gray balanced, and that your CMYK solids are within Delta E of 5.

Once you get your Delta E within the limit, measure now your solids and check your density value per color (CMYK).

These new values are now your personalized standard densities for that particular set of ink and paper. To be on the safe side, you may want to cross check whether the same density values can also be applied when you change any of your materials (ink, paper weight, etc.).

Hope this helps.

Larry
 
Re: Standard ink densities?

> {quote:title=ian wrote:}{quote}
> The values you have mentioned are what we use for coated paper.
> Does anyone have the values for uncoated paper??
> We use
> C-110
> M-110
> Y-95
> K-130

Hi Ian,

Sorry to but in, but do you have values for running Matt/Satin stocks?

cheers!

dwane
 
Re: Standard ink densities?

I am agree with Larry, the choice of standard density and tolernce very costumized depend on the quality of ink (purity, hue error, and rich gamut). Ink level has a density absolute, we put optimum level where no set-off, printthrough. And when it's printed on stock has a specific absorp, we called ink dry back. If we refer on ISO 12647-2, we must set ink, paper, and ink level as certain setting, make sure all combination standard. But dont forget think about TVI, because optical dotgain from penetrate oil was a problem too.
 
Re: Standard ink densities?

Optimum density for ink is determined by measuring the amount of contrast obtained in the 3/4 tone. When you are printing to maximum contrast you will have the highest obtainable color saturation for the color without plugging the half-tones. This will give you the largest color gamut for your ink set.

It will likely be necessary to curve your plates in order to maintain gray balance throughout the tonal range.

Standard densities I commonly see in heatset pressrooms -

K - 1.65
C - 1.35
M - 1.45
Y - .95

+ - .05
 
Re: Standard ink densities?

The reference solid ink densities for uncoated are (based on Gracol 6) -
Y. 95
M 1.12
C 1.00
K 1.25
These are DRY numbers wet are about + .07 for C-M-Y and +.15 for black.
A "secret" is to develop plate curves so that uncoated prints the same dot gain as coated - the color is excellent!
Dan Remaley
412.259.1814
 
Re: Standard ink densities?

1.- the ink should be in values Lab that they correspond to each color and those are according to the iso 2846-1
2.- the substratum should be so that we talked about the standard
3.- they try on the fast colors when printing and should be his moral values Lab according to the board of the standard
4.- having right now those valuables we initiated the measurement in the 80 % to obtain the best relative contrast
5.- we will by default have the optimal densities of the colors CMYK.

1.- la tinta debe estar en los valores Lab que corresponden a cada color y esos son según la iso 2846-1
2.- el sustrato debe estar según lo que hablamos de la norma.
3.- al imprimir se miden los colores sólidos y deben estar sus valores Lab según la tabla de la norma
4.- teniendo ya esos valores iniciamos la medición en el 80% para obtener el mejor contraste relativo
5.- por consecuencia tendremos las densidades óptimas de la cuatricromía.

Saludos

Douglas
www.tecnografico.cl
 
Re: Standard ink densities?

Ink density readings are heavily effected by the emulsion forming properties of your ink and water or the transfer capabilities of waterless inks.
Depending on the void size or white spaces between the transferred ink and or ink-water emulsion to substrate there can be a huge difference in density readings and yet a lower density can appear to be darker and or more saturated than a higher density reading.

Look at a solid with a 50 to 75 power magnifier and look at the spaces(white area) between the transferred ink film.

If the spaces are almost non existent your densitometer will reading light reflected mostly from the ink and not the white area between the transferred ink film.

If the spaces are easily noticeable you will have to carry a heavier ink film to compensate for the spaces between the ink particles to get a similar density reading.

Edited by: Pat Berger on Jul 16, 2008 6:29 AM
 
Wouldn't a standard density also depend on what kinds of proofs you use? For example, if you have and inkjet proof and a KA proof, they rarely match each other because they use totally different methods of color reproduction and simulated gain. Also, I was under the impression that TVI was not just dot gain in that FM screening has no dot structure as with percentage screens but still has "gain", hence the term Tone Value Increase.
 
The following are densities quoted to me from GATF and used by our pressroom. These are all T response densities and we use x-rite densitometers. These are all based on ideal press settings. We use All K&E 918 Bio Supreme Process Ink and K&E Easy Mix Bio Pantones. This is German Ink and in my opinion is the best printing ink in the world. In side by side comparisons with a slew of other ink manufacturers including Superior,Wikoff,Van Son, Hostmann Steinberg, Tanaguchi, Toyo,etc. The K&E Has the highest pigment content, excellent consistency from batch to batch. We are currently running Fuji Plates from a Heidelberg Supra-setter. And we are showing 8-10% dot gain across the board. Packed at 2 over bearer and running Reeves Majestic SRF blankets and Allied All-Star G2 Fountain Solution.

Coated
K:1.80-1.85
C:1.30-1.35
M:1.40-1.45
Y:1.00-1.05

Matte
K:1.60-1.65
C:1.20-1.25
M:1.30-1.35
Y:.90-.95

Uncoated
K:1.20-1.25
C:1.0-1.05
M:1.10.1.15
Y:.80-.85
 
We use on coated:
C: 1,35-1,55(1,35)
M: 1,35-1,55(1,35)
Y: 0,93-1,07(1,0)
K: 1,65-1,9(1,7)

My experience is that it is optimal to run with the numbers in paranthesis above, as they provide us with optimal printing contrast, however it is really a matter of which blankets, colors, fountain solution and plates you use.
 
Going back to the original question - because several of the answers contained either errors or confused language, I'll try and clarify:
Just received a third party process swatch book. In the book it lists the densities that the job was run at. They are:
K: 1.90
C: 1.45
M: 1.50
Y: 0.95
Are these standard numbers? If not, what are standard numbers, or is this simply to vague of a question?
They are close enough to the N America solid ink density targets - which are, for Grades 1 & 2 premium coated paper are:
Yellow 1.05 Dot gain (TVI) 18
Magenta 1.50 Dot gain (TVI) 20
Cyan 1.40 Dot gain (TVI) 20
Black 1.70 Dot gain (TVI) 22:
This is for 175 lpi - i.e. GRACoL 6/7- measured dry (not wet) values.

Some things to note.
SID is an indirect measure of ink film thickness. Coating the paper (or other substrate) with an even and consistent ink film thickness is one of the primary functions the press is designed to do and the press operator is trying to accomplish. But, it does not give you useful information about what color that ink is. So, for example, two patches of 100% Magenta can have equal densities but the hue of the color may be different. As a result, the color you get when you specify from your swatch book may be different than what you actually receive, especially if the swatchbook you're using did not come from your print supplier.

TVI (tone value increase) is/was an attempt to replace the term "dot gain" because it describes more accurately what is happening. I.e. TVI refers to the difference between a requested tone value (e.g. 50% in InDesign) and what that tone ends up being on final output (e.g. 50% in the file becomes 68% in the final press sheet). TVI, also gets around the problem of some devices not actually delivering a dot in the final output. Measuring TVI/dot gain is not dependent on the the halftone screening being used (AM, FM, etc.) because a densitometer (or spectrophotometer) does not "see" dots - it know nothing about screens. It just "knows" about what amount of light is sent to a surface and what amount of light is returned. Dot gain measurements include both optical and mechanical gain. As they both contribute to the final tone we see.
TVI is traditionally used as a metric for maintaining process control as its variance is measured at different stages of the production cycle.
Because it is affected by many variables, TVI should not really be used as a target (I.e. we're trying to get a TVI of 18%). Instead, if the target is to achieve a certain desired print characteristic (e.g. when building tone reproduction curves that are applied to plate output) it is more useful to think in terms of final tones. This means that you don't care what the dot gains are - you just, for example, want to achieve 68% on the press sheet when you ask for 50% in your file.

Print contrast is used to check the quality of press performance in the three-quarter tones. Because it depends to a large extent on SIDs, and it can be altered with a plate curve, it is not very suitable as a variable for standardization (i.e. it shouldn't be used as a metric to determine what SIDs to run at). It is also one of several indirect ways of measuring the maximum volume of ink you can lay down on your substrate. It can also be used to assess various factors such as printing pressure (squeeze), blankets and packing, dampening, inks and additives.
The target is that more print contrast is always better. It is based on a simple principle. As you increase SID from too low to too high the contrast relationship between a 75% tone and a 100% patch of a color changes. When SIDs are too low there is not much difference between the 75% and 100% patches - they lack contrast. As density increases, the difference between the two patches increases or, put another way, the contrast increases. However, as SIDs continue to increase, the 75% tone will start to fill in and hence contrast will start to go down again.
Below is a graphic of an enlarged view of this 75%/100% relationship as you go from not enough SID/low contrast to Optimum SID/contrast to Too high SID/low contrast again:
Contrast.jpg


hope this helps, best, gordo

my print blog here: Quality In Print
 
TVI (tone value increase) is/was an attempt to replace the term "dot gain" because it describes more accurately what is happening. I.e. TVI refers to the difference between a requested tone value (e.g. 50% in InDesign) and what that tone ends up being on final output (e.g. 50% in the file becomes 68% in the final press sheet).
snip
As they both contribute to the final tone we see.


my print blog here: Quality In Print

Gordon,

My point of view is that TVI (tone value increase) makes sense for black screens or continuous black image but not for CM or Y. The equation for TVI can be provided in terms of reflectance or densities with respect to the particular filter for CM or Y. Since the value determined for Density is not really visible by people so therefore the determination of TVI by these filters is not visible. The claim has always been that these tone measurements are visible but that does not hold up for CMY. It does hold up for black.

For the same reason that one can not compare density values for different ink (CMY) and paper combinations, screened or continuous, so one can not compare TVI values between different systems. What one measures is not what one sees. The measurements in a specific system do show a change which is somewhat related to the change one sees.

My view is that there must eventually be a move away from TVI curves use in colour reproduction.

The very useful place for Density and TVI will still be at the press for process control.
 

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