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My question is what kind of black should I use when printing. At the moment I use this black (split into CMYK):
C:0%
M:0%
Y:0%
K:100%
It looks fine in InDesign or Illustrator but if I save a PDF file (for printing purposes) the "color" black appears more like a dark grey on screen.
My question is, if I send this file to print, the color black, on paper, will be black or something like dark grey?
It's one of the Big Things You Must Know about printing that Black (0,0,0,100) is not black; it is a dark gray. I mean really important, as in "If you don't know this, you're going to get in expensive trouble sooner or later." The reason it's gray, rather than black, is that the ink is partially absorbed by the paper and is in any case a very thin coating, so some of the white shows through.
To get actual black on press, you must create what is called a "built black" or "rich black." This is usually something like 60/60/40/100, or 40/30/30/100 as Matt mentioned. You can make a warmer black by using less cyan and more yellow, or a cooler black with more cyan and less yellow. That's a subtlety you want to get some practice with if you ever need to use it, because it can be tricky.
In InDesign and Illustrator there is a preference setting called "Appearance of Black" which can be set to display blacks "as black" or "accurately." For print work, you should always set these to display and print blacks accurately so you don't make an embarrassing error.
The main thing to remember with rich blacks is that your mix should always add up to less than 300% coverage (or whatever your printer specifies as their maximum ink coverage for the particular paper your job will be printed on). Too much ink results in "bronzing" -- a bronze sheen created by a layer of ink that can't be absorbed by the substrate, so it just sits on top. It's also almost impossible to dry completely, so you'll add time to the job.
This is why you must never use the [Registration] swatch in a layout. [Registration] is 100% everything: CMYK plus any spot color plates. Registration marks are the only place [Registration] swatch is used, but they are in the slug, not in your artwork. Your layout program does this for you automatically when you export to PDF and select the option to include registration marks.
Here's an instance where this subject can get very important: if you have a photograph with a black background and you place it on a 0/0/0/100 background, thinking they will merge invisibly, you are actually placing RGB black (which is a rich black when converted to CMYK -- check it out in Photoshop) on top of dark gray. On your screen it might look okay, but in a newspaper or magazine ad it will look pretty bad.
On spot blacks
Many of the other posters have discussed parameters for rich blacks in process colour. It's also worth noting that you can mix spot blacks (and other spot colours in fact) with process colour in documents. For example, it is common practice to print text in a spot black ink on a process colour document.
Process black ink is intentionally designed to be translucent so it can be used to darken other colours. Spot black inks are much more saturated and often used to print black text in process colour documents for reasons discussed below. You will get black if you use this type of ink.
Many commercial printers have presses with more than four colours (i.e. capable of taking more than four plates at one time) and it is possible to mix spot and process colours in the same document.
Printing text in spot blacks is a common application for this technique as spot black inks are much more saturated than process black. Text printed in process black looks washed out and rich blacks are sensitive to even slight misregistration on fine detail such as text type. Usually it is better to print the text in a fifth spot black colour and this is common practice on publications such as glossy magazines.
Other applications for mixed spot/process colour printing
4 colour process has a limited colour gamut and can't match all colours - many PMS colours can't be matched by a four colour process, and specialised effects such as flourescent or metallic colours can't be done with any process colour system at all. Spot colours are often used to match specific colours - perhaps dictated by corporate standards requiring specific PMS matches - or when a specialised ink such as magnetic ink or varnish is needed.
Most print compostion applications (that I am aware of anyway) will support this - you can define colours as being process or spot and the application will make the appropriate separations.
Note that there are also 6, 7 or 8 colour processes which use subtractive colour schemes employing more base colours. This type of colour model also frequently supported in high fidelity inkjet printers. It is not the same thing as mixing spot and process colour, although you can mix spot colours with any process colour model if your budget and printer's capabilities run to it.
Some things are misleading and have not been explained in a very technical way; once you understand how things really work, it's easier to make the right choice.
First, black is not gray, it's black. The reason why it may appear "charcoal" on screen it's simply because it hasn't been enriched with the other colors. But it will print black. Inks are semi-transparent too but it's not a good idea to compare a color on screen with a color on paper.
Officially in the print world, black is always 100% K, and a rich black is anything with value added to the other separation CMY.
There's also what's called the dot gain and it's possible you have some settings in your profile that will render it.
As ink is wet and expands into the paper, especially on uncoated papers (more porous), printers need to adjust their curves of colors to remove a certain percentage of the ink to compensate for this; otherwise all the dots on the paper would touch each others and it will create a result that looks more blurry and will also distort the colors.
When you see a black printed on offset, it's not a 100% pure, it has been converted to a 85% black for example, and the same principle applies for all the other separation. But it's still considered a pure black at 100%. Each printer has its own curve for this but they usually have similar values for dot gain depending on the type of machine they use and which stock the design is printed on.
Some extra Stack Exchange related answers here, and information about dots/dpi/ppi/lpi here
It's better to use a pure 100% black when working with small characters or when the text is printed on a white background.
If a black is enriched for no reason on small characters or graphics, the result might not look as sharp as when using a pure pure because of the misregistration. When press operators calibrate the job at the beginning of the print run, they need to adjust the 4 CMYK plates together and very precisely. That's not an easy adjustment; sometimes they don't really care if it's a low quality print place and sometimes it's their old machines that cannot keep that adjustment for the whole print run. All print shop are not equals, the human factor and investment in good machinery can have a huge impact on the print quality.
That's why on your document when creating crop marks, you will see some little wheels on each sides; these wheels (registration marks) are one tool the press operators use to make sure all the colors are well aligned, that's why they are printed in 100% in each color and very thin. But since machines have some inconsistency, and that process is still done by humans, sometimes the plates are not perfectly aligned; when this happens, you will notice a faint shadow of the other CMY plates appearing around the black, like the sample below.
That's the main reason why it's not always good to enrich the black if it's not necessary; sometimes it's better to use an overprint or a color of black that has very low density in the other CMY so that effect is less visible (eg. 15% or less). And even if the print plates are perfectly adjusted, this can still be a bit visible sometimes.
It's not always the fault of the press operator if this happens; machines are machines, they need to be constantly adjusted too during a long print run, and by default, NO color separation is perfectly aligned on top of each others... otherwise there would be no colors, only a mix of brown! Each CMYK plate has it's own angle, the dots on them technically don't really touch each others.
Some Stack Exchange answer with example and reference.
As you can see, the same problem can happen on the high density colors.
You will need to use a rich for a few reasons and to avoid a few issues as well.
First: If you print a pure 100% black-only on top of another color or picture, the background may appear through the black and will be combined to it on the print plate.
One reason for it that some prepress specialists or RIP system have default settings to overprint black that is at 100% black-only; it will create a "multiply" effect and merge all the black together (example below.) For example, on one part of the design, the black will look rich because the other CMY on the picture or color under it will enrich it (saturate it), and the black-only part on the white area or other full color will have a different color value/recipe. In other words, it will overprint that part of your design. on the other parts
It's not always obvious to see this on screen because of the different gamma and calibration of the display, so when using black surfaces or texts that overlap other elements, it's better to add some values in the other CMY colors to make sure this doesn't happen. It doesn't need to be a high density of black; it can be only 1-1-1-100; by doing this, you make sure that a 1% value is added to the other plates CMY, and to tell the RIP "this is not a pure black but a rich black".
The higher the density of all the colors together, the longer the ink will take to dry, that's why you may prefer to not totally use a high density rich black.
No, there's no RGB colors mixed with the CMYK colors.
I amplified the effect on the example below but that's pretty much what will happen once printed. On your screen though, that black part will look totally opaque and will give cover the image properly.
Second, it may make a more balanced and smooth print finish
In offset printing, rolls apply the inks on the plates, and then that plate will stamp the paper. Sometimes these rolls are not well maintained, are old or there's some saturation of ink on them for high density prints. Sometimes it's simply because of the way the design has been done; with large colored areas, the imposition (eg. How the design is placed large print sheets) needs to be done to create some kind of "flow" when the cylinder rolls on the sheets. If there's huge white areas between high density ones, it will create an effect of stamping because the ink roll will apply more ink in some places and none in others. That's another reason to choose a quality printer who will care about these details.
All this will create the same kind of effect as when actually painting a wall using a paint roller and the color will not be applied evenly.
The same happens for any color or 100% Pantone color used on large colord areas.
Basically, if you don't help a bit the press operator by enriching the black, your black could look like this (I use blue on the example to show the "stamp" print clearly):
That's when you want to use a rich black with enough density in each color, but not more than 300 in total of all the CMYK added together. By adding more density to the other colors, you help hide this effect that you cannot really control otherwise; it's a bit like applying 4 coats of paint on a wall instead of 1, the area will be more saturated.
That's another reason why you have to be careful with any 1-color project and using large 100% areas.
Third, sometimes RIPS ignore your overprint settings
Sometimes, your trapping attributes are simply ignored. It's normal they are ignored because few designers have real experience in prepress and will add these settings where they shouldn't or by mistake. So people at print shops will simply remove them and do the trapping themselves.
This is trapping on the image below. Again it's done to make the colors blend properly together. Each color is outlined with a very small border that will be overprinted on top of the other colors OR overprinted to add the background and foreground color together (multiply effect) OR knocked out to make the foreground color totally equal with the background or even remove it (use on white usually).
It requires some analysis for some print jobs because adding trapping might bold a bit some text or shrink it; so it's done according to the darkness of each colors and how they touch each others. For example, a yellow text on black will have a trapping added to it because the yellow will be hidden by the black, but in the case of a dark blue text on yellow, the yellow will go a bit under the blue instead. If it's not well done or no trapping are added at all, there could be a very thin white border visible around some elements.
So if you used an overprint on your small black text to make sure there is no white border around your text once printed, it's not 100% certain that this setting will be respected. The best way to ensure your small texts are overprinted is to simply use the value of the color on the background and add 100% black to it; this will create the same effect as an overprint 100% black-only on a color without the overprint trapping.
Also, when using a light gray made of a different opacity of black, it's better to use a rich black; this will become a rich gray and will hide the small dots on the print. The lighter the color, the smaller and distanced are the dots; they are clearly visible at less than 20% opacity if there's only white under that gray part of the design. That's why when doing a CMYK project, it's better to use a rich black even for the tones of grays.
A note on trapping: Usually, trapping is done on vector elements (vectors and fonts) but not on rasterized elements (pictures or text done in Photoshop). It a good practice to add some trapping yourself on your Photoshop layouts for this reason. I personally use a 1-2 pixels depending on the size of the image. I do it even for web projects, it decreases the anti-aliasing effect as well.
Other Stack Exchange details on why to use real colors and not opacity
Finally, it's better to use a rich black on gradients
When printed, gradients are split into stripe for each % of density/opacity. These steps ARE visible on large gradients, and lamination or varnish will amplify this effect because it will darken a bit the colors.
That's why it's important to enrich the black in this case; it will soften that effect of steps.
There's many reasons why one recipe of rich black is better than another, and it depends on your design.
First, maybe you want to tint your black. If you use a higher value of cyan, the black will look a bit colder, and if you use more yellow it will look brownish. For some projects, it would look weird to use a rich black that has a blue hue if the other colors are warmer, for example. And for some projects, it would look weird to have a tinted black of any color, that's when you'll use equal values in all your color, preferably a little bit more blue to make the dark gray-black and not brown-black. It can be a 5% difference only.
There's also very nice special effects that can be created with rich blacks, especially when using gradients or different tones of this black.
Adding other colors in your black in certain proprotions, will also cancel each others or appear more like a metal black, with no tint. The best way to see how it will look like is to use it on a gradient.
If a picture on your design already has a high value in black, it might be a good idea to use the same value so they don't look like 2 different colors. Of course if this value has a higher density than 300% (which is often the case), the picture should also be adjusted using the levels or curves in Photoshop.
Example of a warm rich black used with a green tinted rich black:
Sometimes it's really hard to choose the right tone of black. You can always ask your printer, he has a "favorite" recipe usually that prints perfectly well on his machines. I like to use 40-30-30-100.
It's important. This way your screen won't trick you on the real appearance of black. Everything should be set to be shown accurately in every publishing software you use.
Details are always "amplified" when printing on offset, and it's better to control as many details as possible to avoid issues. It's very disappointing to realize a details was forgotten once you hold the printed brochure or catalog in your hands!
Source images: Offset print cylinder - xperienceyoursite.com, Minolta logo - danielsprint.com, Misregistration on black - prepressure.com, Trapping - graphicdesign.spokanefalls.edu, Dot gain close up: netdna-ssl.com, Dot Gain printed picture - underwaterphotography.com
Ask your printer what to use. Your printer may recommend Rich Black, which is actually a combination of layered CMYK inks.
If you're printing CMYK, add some CMY to your K and you get a rich black. It's darker and comes across are a more 'true' black when printed. It also helps with trapping and as you're less likely to see white gaps if your registration is slightly offset. As for how much of each to add, that can depend on a number of things, but Lauren is pretty much correct: ask your printer. Then it's their problem if something goes wrong. ;)
In pre-press, we usually add a BOOSTER to black. The best way is to use:
100 BLACK 40 CYAN This combination will result in a rich black required by the press.
Every Tom, Dick and Harry working in the press running your files will love you if you make your heavy coverage black in your document. That 4o% of Cyan is what we call a "booster".
However, if you want black in your text, just use 100% black. Always remember also that Black "always" overprint. It's like the "grass" in that poem: "I am the grass".
"Cover the bodies high in Ypre and Verdun Cover them under and let me work I am the grass, I cover all."
I'm sure you get my drift :)
I have often used 40/30/30/100 which produces great results.
There are two more cases where black will be used when printing 4-C that might be handy to know about.
GCR, Grey Component Replacement, and UCR, Under Colour Removal, are two additional uses of black in 4C printing.
Grey component replacement substitutes a portion of the black where there are equal amounts of the cyan, magenta, and yellow which equals neutral grey anyway. This is done to keep the ink coverage in a layer thin enough to dry well. This is usually 250% of the ink coverage or less.
Take the colour:
C =34%, M =47%, Y =12%, B =18%
Subtract 10% of the colours, say, and add the equivalent to the black and we get
C =24%, M =37%, Y =02%, B =28%
which gives the same printed colour using less ink because the grey created by using 10% each of c, m, & y is equal to 10% black and can be removed by substituting the cheaper black ink. The shadow blacks will be rich and full with more detail evident in the shadows than with heavy ink layers even with good registration.
Beautiful B&W images made with 4C printing are also richer than you can get with black ink alone. This is due to the use of rich black in the print.
Under Colour Removal is a similar technique but it removes all of a redundant colour where there is an overlap of ink.
Using the same example colour as before:
C =34%, M =47%, Y =12%, B =18%
We'll now remove all of the least-used colour (Y) and add the equivalent of black
C =26%, M =39%, Y =0%, B =30%
gives the same printed colour using less ink because the grey created by using 12% each of c, m, & y is equal to 12% black and can be removed by substituting the cheaper black ink.
Here is my answer about some other way to consider rich black.
On specific cases use whatever combination of inks your color profile gives you.
Imagine you have a black photo of a night sky. This photo was obviously taken in RGB, well, when converting it to CMYK will give you some CMYK values. Use those, period.
A modern print machine and inks combination can handle this "high ink values", that is what a printer profile is for.
This TAC (Total Area Coverage) or maximum amount of ink will vary from profile to profile, especially will depend on the type of paper used: Coated, uncoated, newspaper, toilet paper.
On a coated paper some profiles will go as high as 350! Of course, only in Japan. A popular profile is Fogra 39 which has a TAC of 330% ish, but for normal use, you want your TAC on the 300% max limit.
Fogra 39 c91m79y62k97 = 329% Fogra 29 (uncoated) = c96m70y46k86 = 298% (Still, on uncoated paper 300 is too much for me) On the oldy SWOP 2 profile, this will give you c75m68y67k90 = 300%
The usage of these values, in practice, could change inclusive depending on the weather. On not so optimal conditions ink could take a bit more to dry.
Note one thing about these maximum values. None has black at 100%. It is for a reason. In the old days, when the screening was done by hand there was a rule that you should not go beyond 95% ink and less than 5%.
When you have a gradient, there will be an abrupt change in it when the droplets of ink touch and the ink of them could mix (dot gain) if you stay below 95% max ink of any color, you can have smoother gradients and more uniform color. (go-junta mentioned it)
This is one of the reasons I do not recommend old-style recipes like 100k 50% cyan or stuff like that. They were prior to digital profiles took over.
When you have a duotone where black is one of the inks, you could send your darkest color as 95% black and 95% the other ink. Well, you could do that with whatever colors you are using...
This is not strictly overprinting, but let me explain.
If you have a drop shadow on a background, let's say a lime one (c50%y100%) the darkest color could be c50% y100% k95%. Try to stay below the 300% line and the 95% max black if you have a gradient.
The idea is that you add black ink on top of your existing color.
There are some other strange cases where you could pass twice the black plate.
On small text keep only the black channel.
In addition to everything else mentioned with regard to settings, theory, good advice, and best practices…
When you submit your job for printing, ask for a "contract proof" which will show you what your job will look like when printed, in hand, before the presses roll (jump, flip, zoom, or whatever they do now). By providing you with a contract proof your printer is guaranteeing that the job will look like the proof.
Armed with this print, your printer is legally bound to produce a job that looks exactly like your contract proof print when delivered, or better.
A contract proof is a legal document that when dated and signed is your insurance of an acceptable result. You can take it to your client for approval. When they sign it, you are covered and not responsible if there is a mismatch. You can keep it for reference to compare with the press proof before you give the okay for a precise or tricky press run.
When pulling press proofs, pull and number at least a half-dozen to compare the print continuity and colour coverage, ghosting, slurs, etc. Ask your important questions and then give the approval when you are sure it looks acceptable.
I don't usually use an Absolute Black unless it is background. Usually I use a 60-80% black (charcoal color) for type. Not only does a charcoal look great and polished, it also saves printer ink by not using the toner too much (?)
It will print black. Both of the leading DTP packages I have specify "black" and "registration" as 0;0;0;100. As to why your software is showing it as gray: you have a monitor profile which is being used to adjust the displayed color to simulate the desired color.
Note that CMYK is a reflective or subtractive color model and your monitor has to simulate this using an additive color model. There are always colors which cannot be simulated.
Rich black is black often with a hint of yellow added. It looks less flat on the page, but Lauren Ipsum is right: ask the printer. There are technical reasons why you might not want to flood large amounts of all the colors on the page.
