I am paper bag manufacturer, on daily basis we are dealing with graphic designers and printing operators.

Often I am receiving orders for 2-color or 3-color printing. I conveyed the same message to designer. But sometimes the print operator analysed the design report me hat the design contain more than two or three colors.

This issue mostly arose when using modern color variants. I got somebasic understanding about RGB vs CMYK.

The reality is, I am more interested to use modern design and colors to get the best result, meantime i can't use extra colors as it is chargeable.

So, my expectation is,

  1. Does anyone have any practical solution to handle the situation better way.
  2. How do I check numbers of colors used in the Design? In terms of CMYK basic and combinations.
  3. Any resource available to get more knowledge about color combination. For example, by using two basic CMYK color (ex: cyan and yellow), how many combinations can be produced.
  4. What are the information i need to gather/convey to print operator, Ink producers and Designers and so on.
  • 3
    Hi. Welcome to GDSE. Perphaps do some research on the difference between spot colour printing versus CMYK (4 colour process printing). There's a brief explanation here. When a printer says "2 colour" it usually means 2 spot colours. Your designer should know this. If not, hire one who does.
    – Billy Kerr
    Commented Jul 26, 2019 at 9:07
  • After separation/colour breaks, there should only be one plate for each colour. Two plates for a two-colour, three for three, etc. 4C / process colour uses 4 plates, etc. That's one (basic) way to explain the difference. Black & process yellow would be a 2 colour job.
    – Stan
    Commented Jul 26, 2019 at 15:43

4 Answers 4


Construct a Custom Process Colour Tint Book for reference

You can purchase Colour Tint Books printed on uncoated white paper stock.


This is okay if you are always printing on white stock. If you have coated stock, the colours will be off compared with the dominant tint of the paper stock. Inks are transparent and screen angles must be consistent.

It might be worthwhile to invest time and money to make a print run of Colour Tints on your paper stocks if they are not normal white stock.

If you use Kraft, then it would be valuable to have as a contrast and comparison with brighter stocks. The dominant colour of the background stock would be invaluable to designers when evaluating the effect of the colours and colour combinations used.

Ideally, you would create a separate Colour Tint Book for every different kind or colour of paper stock.

What is it

A Colour Tint Book is an exhaustive example of what a press check would look like with every colour printed with a press in an orderly and documented manner.

It is divided into sections. Yours would have a section for each colour combination — 1 Colour, 2 Colours, 3 Colours.

Fortunately, A digital file is available for download as a PDF and Illustrator file from


The files online have one colour grids in 5% increments for each of the process colours Add black and you have an example of 1 colour variations.

Scrolling down to the next page presents a 2-colour grid with Magenta steps across the top and Yellow steps vertically, each in 5% increments. This is the first of a 2-colour set of grids. You can use the supplied as examples to make to complete your set.

Unfortunately, files you might find useful are not complete. Missing is an example of Magenta and Cyan, Cyan and Yellow, and each one with Black which should show all of the 2 colour job variations.

Going further shows all of the 3-colour variations. Section 2 (three colour) would be composed as above but each successive page would have percentage changes in an orderly stepped manner. Page 1 would have a 0% tint added to each of the cells in the grid. Page 2, 5% tint, and so on.

I hope I've interpreted your question correctly and this is of some help to you and your colleagues.

Good luck.


RGB and CMYK are both methods used to represent FULL color art. What you are talking about is spot color printing. The letters in "RGB" (red, green, blue) and "CMYK" (cyan, magenta, yellow, blacK) describe the color channels used to build a full color image. RGB is used for monitors and CMYK is used for print. Even when you print an RGB image, the printer seamlessly converts the RGB to use its CMYK ink cartridge or toner.

Most digital printers, like ink-jets and laser printers, do not support spot printing. Spot printing (on paper) is mostly done on offset presses. While a growing number of digital printers have additional ink or toner stations that can add spot colors, these are still relatively rare.

If you want to print a company logo that is blue and green, you will need to have your designer assign the blue to a dedicated blue channel, and the green to a dedicated green channel in the software. Photoshop and Illustrator are both capable of doing this, but Illustrator usually makes it a lot easier, especially if the logo is in a vector format like .EPS or .AI. In Illustrator, you can easily convert any existing color swatch to a spot swatch that will then behave like a color channel (separation) when printed.

You mentioned that you have InDesign. It does support spot printing very well, and can show you any spot colors that are used in your file, but it is not the optimal software to create the separations. My recommended "best practice" is to create your spot images in Illustrator and then place them into an InDesign layout for separation printing or PDF export.

This should get you started. There are tons of tutorials that will show you the specifics of how to set these features up in the software you have.


I hope you are not changing the printing operators too often. They are a valuable asset to your company. I will only address the designer's part.

The design contains more than two or three colors. I got some basic understanding of RGB vs CMYK.

O here is the bad news. A 2 or 3 ink project is not either of those. It is a Spot or direct ink project. This is using a direct ink catalog, The most commonly used one is Pantone.

As you can see on this image when I measure the color of the "wine" color, it is marked as the one and only ink should be used to print that part.

enter image description here

But when the file is not prepared correctly, to make that "wine" color, you should use 4 inks to be mixed on the print and generate the color.

enter image description here

Normally you use the 4 inks color CMYK process when printing what it is called a full-color print, where you have photos or "colorful designs".

But you still can print photos with only spot inks.

Here is one example on how to play with two inks on a photo. Preparing design for duotone printing? But that is just for a photo. On a LOGO the file just needs to be sent with the correct spot color on each element.

In terms of CMYK basic and combinations.

I already stated that you do not use a CMYK file. That is the wrong approach.

But if you wish, you can print a color atlas it is a file that looks like this

Do not use this one, as this is an RGB file. I will try to upload a CMY one later.

enter image description here

But this is very tricky, especially because I m pretty sure your bags are not simply white coated paper, like the ones used in a magazine cover. So the colors react differently to different materials, and colors.

how many combinations can be produced. (on a C+Y combination)

The one person that needs to know the difference is the designer sending the file or you simply charge them the adaptation of the project and send it to a Designer that knows the process.


How do I check numbers of colors used in the Design? In terms of CMYK basic and combinations.

That depends on the file format that you are using. ?

Any resource available to get more knowledge about color combination. For example, by using two basic CMYK color (ex: cyan and yellow), how many combinations can be produced.

When you combine two colors (process colors) you need to raster. This is much more complicated than printing spot colors where each color is separate to the other. The number of combinations is in theory endless but depends practically on the number of shades that the output device can generate for each process color. And this in turn depends on the resolution of the output device. But if your printer usually only prints spot color it will probably be problematic to send him a design where colorants are "overprinting". There is technology around that allows you to convert a design with CMYK/RGB colors into spot colors so that the technology does automatically pick the "best" spot colors out of a number of available spot colors.

  • Are you confusing solids and halftones/raster and screening? I find this answer is confusing. Please verify terminology that you used.
    – Stan
    Commented Jul 26, 2019 at 15:35

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