On doing a nice GREY with CMYK

[SebastiaoV]

Hi guys,

I know if I need a good solid and dark black i can always use an "enriched black" let´s say

C=50, M=0, Y=0, K=100

I am doing a design which i will need a strong GREY, let´s say 80% black. The problem with that something the grey does not cover that well. The client told me to use CMYK so no pantone ink will be available for that. The question is how to get a good and strong GREY with CMYK? If i put more Cyan as the enriched black the color will turn and it will not be straight grey, more of a bluish grey.

Any ideas? Thanks for the help,
Sebastiao

[Björn Öst]

Try adding a neutral cmyk build to the black, like 30c 22m 22y.

[SebastiaoV]

Hi Bjorn,

Thanks for the tip!
So a 30c 22m 22y will give me a good grey in printing? By the way, Can I add some Black to make the Grey darker or more intense?

[Björn Öst]

Yes, that was just the cmy part, add whatever black is needed for your preferred "darkness".

In swedish newsprint those numbers are used to maintain correct color in the presses. They place small squares with 30k (the black value varies a bit depending on the dotgain of the press) and 30/24/24 cmy squares beside each other along the margins or edges. Then when the press is correctly adjusted both squares should look as similar as possible.

I guess there is no problem using a fuller mix such as 60c/48c/48c and some black for a darker grey either.

P.S I wrote the wrong numbers in my first post, it should be 30/24/24 cmy.

[Sandee Cohen]

Bjorn,

Why the higher cyan amount? Won't that give you a cooler grey than neutral?

And why use the same cmy formula for all different tints of k?

I would have created a rich black of 100k, 24c, 24m, 10y and then saved that as a swatch.

Then, if I needed a lighter grey, I would have made a tint of the rich black. So that a 50% tint of the rich black would have actually translated into 50k, 12c, 12m, 5y.

[Björn Öst]

Equal amounts should theoretically produce neutral grey, but it doesnt in practice. No idea why, though. Maybe different densities of the inks, or how it soaks up in the paper? It shows on screen too, try 30/30/30 cmy, it will have a reddish cast.

I agree on just scaling down your favourite rich black mixture. As long as that rich black produces reasonably neutral tones.

[_Eric_Otto_]

A good starting point would be to create a new swatch using the warm or cool greys from the Pantone solid colors, and then convert them to CMYK process.

[_J_Maloney_]

Keep your screens below 75% if this job will print offset. A 4/c gray will give the pressman trouble regardless of how your job prints. Be prepared to get a very warm or a very cool gray -- and not what you expected (time to get a new printer!).

Check out a newspaper, where all some pressman care about is the little gray boxes that swing from warm to cool. During one press run. That and not plugging up their 75% screen.

J

[p_taz]

There is no set cmyk value for rich black, it is different for each output scenario. That is what colour management is for.

If you start with a neutral LAB value (as I understand it) then convert to a printer's profile, you should theoretically end up with a neutral on press.

From a printer's point of view, that is only a starting point and I would advise the pressman exactly what you are looking for as he will adjust press settings to balance the colour for current conditions which are unpredictable in all but the most specialised printeries. For a general commercial printer, you should make sure they understand what you are looking to achieve and start with numbers that will make that possible as mentioned at the top.

For the record, my personal preference would be a max colour of about 60/40/40/90 which would bias the grey to the cool side but give plenty of weight to work with....

[p_taz]

Of course, the colour I mentioned is more of a black than a grey but scaling that colour back in proportion can give the kind of grey you want.

[_rob_day_]

A Lab swatch converted to CMYK would give a color managed neutral with the correct amount of black generation. So, make a Lab swatch with a and b set to 0, double click the swatch and set the Color Mode to CMYK. Lab 30|0|0 converts to 71|58|58|30 with US Sheetfed Coated V2 profile.

[Sigler Express]

If you want a rich black its 60C 40m 40y 100k