How do I adjust the level of black in a photoshop file?

Question

I don't claim to be an expert in print media, but I have been getting stuff printed professionally for a while. Today I'm using a new printer for the first time, and they've come back asking for this:

"Ideally we could do with the black being reduced though to 40% Cyan,40% Magenta,40% Yellow,100% Black, as this is the maximum coverage our press can take."

I don't know what they're asking me for to be honest - how can I globally adjust the black in my images? I'm using photoshop and sent them PDFs.

Any help appreciated, I need to get the proofs signed off today.

Answer 1

They are asking for a specific case of rich black. Take a look at this post and answer. When should I use rich black? and What kind of black should I use when designing for CMYK print?

But in this specific case, in my opinion, they are asking for an old, archaic, pre-digital era rich black.

Today, the maximum ink "the press can take" TAC (Total area coverage) should be given by the color profile they are using.

The values that they are asking c40+m40+y40+k100 equals 220. a 220 could be the maximum ink a paper+ink+climate+press combination can take, yes, then you need to find a color profile that gives you that TAC. But normally those low levels of ink are for uncoated paper.

But even if you are using an uncoated paper, those values are "artificial".

If you are using a coated paper, on a flat sheeted press, the values are given by a profile like Swop 2, or Fogra 27 that have a TAC of 300%. A lower percentage could be required using coated paper but in rotography.

Answer 2

Coated paper can take less ink than uncoated, because uncoated paper absorbs much more ink, due to its rough surface. Also, depending on the type of paper, TAC can be 220% ( if you have a large amount of print, they can speed up the printing process if there isn't too much ink to dry. The quicker the print process, the better (from the printer's point of view).

Also, from their requirements, it seems that it is not a digital press, but an offset lithography one. In any case, if you have a large area of black, it will definitely look much better if you make it a rich black rather than a 100% black (that may give you a pale look). If you don't manage to get their color profile, you'll probably have to do it manually

To do so, you can select the layer(s) with black areas and go to image - adjustments - channel mixer; switch to the black channel and add 40% Cyan,40% Magenta,40% Yellow into it. That way you will use the same information you have in the black channel in the other three channels, only the amount will be 40%. Bellow, you'll get the TAC, for checking.