Exploring CMYK, Spot Color, and Process Printing

Ben Buzzard
August 16, 2023
Spot color print on press, using red and yellow ink.

Screen printing allows for the creation of vibrant and detailed designs. However, not all screen printing methods are equal when it comes to reproducing colors or design details accurately. Here we will take a look at the three major screen printing styles CMYK, Spot Color, and Simulated Process screen printing.

First we will take a look at CMYK printing, which relies on combining Cyan, Magenta, Yellow, and Black (also called Key). We will see how this method achieves a range of colors, as well as its advantages and limitations.

Then we will take a look at Spot Color screen printing, the most common screen printing method used around the world. It’s a technique that focuses on reproducing colors with precision. Usually used alongside the Pantone Matching System (PMS) to ensure color accuracy. We will look at the benefits and limitations of Spot Color Printing, and why it is such a big part of screen printing today.

Lastly, we will go over Simulated Process screen printing, a technique that combines halftones and spot colors to achieve a detailed, and photo-realistic print. We will work to understand the unique advantages it offers, as well as the pains that come along with it.

By the end of this post, the goal is that you will have a clear understanding of the differences between CMYK, Spot Color, and Simulated Process screen printing methods. This knowledge will empower you to make informed decisions when choosing the right technique for your next print. You’ll be able to take into account factors such as color accuracy, complexity, and cost-effectiveness.

CMYK Screen Printing

CMYK Screen Printing of a Car.

Definition:

CMYK printing, also called four-color process printing, is a popular screen printing technique. The name CMYK is an abbreviation of the four ink colors that are used in the process, Cyan, Magenta, Yellow, and Key (Black). The CMYK model is based on what is called subtractive color, wherein each color absorbs or “subtracts” wavelengths of light, helping to reproduce accurate hues and shades. Cyan absorbs red light, Magenta absorbs green light, Yellow absorbs blue light, and Black is used to enhance contrast and details. This allows for reproducing a wide range of colors accurately. An example of how CMYK printing works, below is a scaled up version of a few colors and how they would be produced using this method.

CMYK Halftone

Process:

To get ready to print CMYK we must first separate the artwork into the appropriate channels. In Photoshop we must convert the file we want to separate into the correct CMYK color space for your inks. At Extreme we use Avient Process colors for our plastisol four-color process printing. The file for the download can be found here.

After converting the file to the CMYK color profile we will want to compare it to the source file, and using the “Selective Color” adjustment modify each color channel until the colors match closer to the source file. We do this because CMYK doesn’t have the same color gamut as RGB. See the diagram below that represents the difference between Adobe RGB and CMYK color spaces.

aRGB vs CMYK

For more information on preparing artwork for four color process printing, Ryonet has a great article that goes into depth about all the steps needed. That article can be found here.

Advantages:

Printing with CMYK has the distinct advantage of utilizing only four printed colors to reproduce the design to a high degree of color accuracy for most clients' needs even when aiming for heightened realism such as in photographs. The separation process is relatively quick to do with not needing to do any manual separations and only have four channels to adjust and work with. The CMYK process ink colors are also relatively inexpensive when compared to mixing colors, and you do not have to custom mix colors for each job.

Limitations:

As is visible in the diagram above, CMYK printing does have a limited color palette that falls short of the full spectrum of colors that might be utilized in photographs and other artwork. Colors that are not possible to reproduce using CMYK are vibrant and saturated blue, green, orange, red, violet, and purple shades. Fine detail in darker shades may be hard to reproduce accurately as well. This method also requires a white or light colored background to print on, if printing on a dark colored garment a white underbase must be used.

Spot Color Screen Printing

A spot color print of Coleman Young in the POP ART style.

Definition:

Spot color, also called solid color, or Pantone printing is by far the most common screen printing method used today, and has been around the longest. Unlike CMYK printing which combines four colors to create a spectrum of colors, spot color printing uses individual inks, each color matched to the predefined color. Spot color printing is particularly great for logos, brand colors, and whenever an exact color match is required to be printed across all print mediums.

Process:

Spot color screen printing requires designs featuring solid colors without gradients or blends. Setting up a design for spot process printing involves separating the design, assigning a unique PMS color to each distinct color within the artwork. It's important to note that each of these color channels will correspond to a separate screen, so we need to make sure that the job is compatible with the available heads on your screen printing press. This approach will get you optimal results and consistent color reproduction in spot color printing projects.

Pantone Matching System (PMS):

The Pantone Matching System (PMS), developed by Pantone LLC, is a globally recognized color matching system used across a wide range of industries. This system is important for consistent branding, while also ensuring color uniformity across various projects. Being one of the most widely used standardization systems, Pantone color library has over 2,000 distinct spot colors. By referencing these PMS colors alongside the physical color guide, this system allows for clients and printers to guarantee the colors printed are the same as the ones the client envisioned.

Advantages:

Spot color printing has some distinct advantages when compared to Simulated Process and CMYK. The largest benefit is its unmatched color vibrancy and saturation. By using only solid colors, spot color printing ensures that each color has maximum intensity, resulting in an impactful design. As well, the use of special effect inks is available when using spot color printing, allowing for the use of glow-in-the-dark, metallics, and fluorescent/neon colors. These special effects would be unattainable through CMYK printing alone, thereby enhancing the uniqueness of the final output.

As well, spot color printing can be more cost effective in cases where we have larger print runs or projects with a limited color palette. The process of preparing individual screens for each color simplifies production logistics, making spot color printing the economical choice for both large runs and small color count orders. By leveraging these advantages, spot color screen printing emerges as a compelling option for achieving vivid, dynamic, and cost-efficient prints.

Limitations:

Spot color printing is accompanied by several noteworthy limitations. As previously mentioned, one notable constraint is the between the number of colors and available print heads on a screen printing press. Each unique color requires a separate screen, which could result in challenges for designs with a large color palette. As well, due to the nature of spot color printing, recreating photo-realistic images or color gradients may not always be possible, restricting its suitability for certain projects.

The artwork separations also require some extra attention, with a few manual adjustments to ensure optimal color registration. Underbases, used when printing on dark substrates, require choking the outside edges to prevent the underbase ink from peaking.

Simulated Process Screen Printing

A simulated process print of the 40th St Guitar's mascot.

Definition:

The purpose of simulated process screen printing, sometimes called spot process printing,  is close to that of CMYK printing: to achieve photorealistic results, and to be able to print designs with gradients, tones, or complex color blends. However the way of achieving these results varies drastically between the two. Unlike the transparent CMYK inks, this process uses opaque spot color inks to emulate a wider and more diverse array of colors. The final prints are richer and more accurate than traditional CMYK printing. 

Process:

With simulated process, like CMYK we are going to be using halftoning to blend ink colors together to achieve a winder array of colors than we are actually printing with. When it comes time to separate a simulated process design we are going to be looking for the most prominent colors in the design, and pulling those out to use as a few of the main inks. This can be done manually, or we can use software to help with this, a few of the most popular are UltraSeps, QuikSeps, or Separation Studio. These softwares will help with automating picking out the colors to use, and even rip the designs into halftone printable one bit .tiff files.

Advantages:

Simulated process printing offers quite a few distinct advantages over spot color, or CMYK printing. First is the ability to pick the colors to use in the separations. This allows for a more accurate print. In the design above, if we tried printing in CMYK, the reds and yellow/oranges would be a lot less saturated, and would not match the brand colors for this company. We are also able to incorporate specialty inks into simulated process printing giving us the ability to include metallic, glow-in-the-dark, puff, etc. into the design.

Additionally because the spot color inks that are being used are not transparent, it makes for a much easier time printing on a darker substrate. We will also find it easier to print simulated process designs on a multitude of different substrates without having to modify the separations.

Challenges:

Simulated process jobs can be a lot harder to get the separations correct when compared to CMYK or Spot color printing. Even with using the paid softwares to assist in separation of the designs, you will most likely need to do quite a bit of manual adjustments of the channels to get an accurate print. Even after adjusting the channels to get the best results you can, it’s likely that we will only be able to have 70% color accuracy. As well as sometimes needing to use a lot more screens than CMYK, the cost of printing a simulated process job can be considerably higher.

Though the biggest hurdle when it comes to simulated process is the separation of the artwork itself. It takes a lot of skill, and time to do a manual separation of a design. If it is your first time working with simulated process printing, expect to have to tweak the separation multiple times. Even when using the assistance of separation softwares like those that we listed above, there will still be some manual adjustments that need to be made to get as perfect of a print as possible.

Comparison and Conclusion

Comparison:

In general, CMYK printing is optimal for full-color reproductions, spot color printing excels in color accuracy and branding, while simulated process printing is specialized for achieving photorealistic prints with a curated color palette. Each technique has its strengths and considerations, offering distinct solutions for various printing needs.

Choosing the Right Method:

When looking at what method you would like to use for your next print, there are a few things to consider. If your design only has solid colors then luckily Spot Color printing is the way to go. It gets harder when deciding to print between CMYK and Simulated Process. If your print has more muted tones, like reproducing a photograph, CMYK will most likely work the best. If we are looking for recreating designs that have bold colors, gradients or color tones then Simulated Process is probably the way you would want to go. If you ever have any doubts on what kind of printing would be the best for your design, our customer service team is always more than happy to help make an informed decision.

If you have an order that is a Spot Color design and are ready to get started on it, we recommend checking out our Product Catalog here. If your design leans more towards CMYK or Simulated Process, you can get a hold of our sales team by either using the Contact Us form, or send us an email to support@extreme.ink and one of our account specialists will get back to you with a more accurate quote.

Ben Buzzard
Updated:
August 16, 2023