Printing Ink: What does “Heavy Coverage” mean?

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What is Heavy Coverage?

In the context of commercial printing, Heavy Coverage refers to an application of ink that covers a significant portion of the paper substrate. It can also refer to a dense saturation of ink, whether applied as a flood coat or to specific areas. In either case, the substrate receives a substantial amount of ink, much more than what would be considered light or medium coverage.

Heavy coverage is often used to create solid backgrounds, whether it's a vivid color or an intense black. It is also used for full-page images and bold designs that need to attract and hold attention, such as the covers of books and magazines or promotional pieces like brochures or postcards.

A few words about Offset Printing Ink

Offset printing uses liquid inks that have a high viscosity. The ink is very thick because it needs to transfer through various rollers before it makes contact with the paper. The thicker, more viscous ink helps maintain precise control through the various transfer points and also maintains the pigment density needed to create vibrant impressions.

Though the offset process can print any of the Pantone ink colors, the vast majority of color printing performed on offset presses is created using the 4-color process technique (a.k.a. CMYK printing). The 4-color process method uses Cyan, Magenta, Yellow, and Black inks in various percentages to create full-color images. Each of these four inks is applied in a concentration from 0% to 100%. Also, the inks are laid down in successive layers, one after the other, as the paper travels through the press.

The intermingling of these 4 ink colors on the paper can create thousands of different colors. For example, a Dark Red ink color can be created from layering 0% Cyan, 100% Magenta, 100% Yellow, and 45% Black. Likewise, a Navy Blue ink color can be created from layering 100% Cyan, 100% Magenta, 0% Yellow, and 50% Black. These formulations add up to 245% and 250% respectfully, which are below the recommended maximum ink application of 300% for most offset printing presses.

On the other hand, Registration Black is a color made from 100% Cyan, 100% Magenta, 100% Yellow, and 100% Black. It is the darkest black color that can be made from mixing the four CMYK colors. However, it is only used for registration marks and trim marks. Why? Because its formulation totals 400%. This makes it an impractical color for printing because it would apply too much ink to the paper.

Being mindful of heavy ink coverage is important because the more ink applied to a paper sheet, the longer the printing will take to dry. This can lead to smudging or inked images being transferred to adjacent sheets as they exit the press into a stack. Also, depending on the absorbency of the paper being used, too heavy of an ink application can lead to images losing detail and the paper becoming wrinkled from over saturation.

A few words about Digital Printing Ink and Toner

Digital printing presses also use the 4-color process method (CMYK) to produce full color printing. Some digital presses even use liquid ink. As such, heavy ink coverage can pose some of the same challenges as it might for the liquid inks used in offset printing.

Having said that, the majority of digital printing presses use toner instead of liquid ink. Toner is applied to the paper through the use of electrostatic charges, heat, and pressure. The toner is a fine powder made of granulated plastic particles, pigments, and various other compounds.

The toner receives an electrostatic charge. A laser or LED light beams the images to print onto a rotating metal drum. These image areas receive the opposite charge that the toner was given, which attracts the toner and causes it to adhere to the drum. The paper substrate, which has also been given the opposite charge as the toner (and an even stronger charge than the drum) attracts the toner powder from the imaging drum as it passes across it.

Most digital printing presses use a negatively charged toner and a positively charged drum and paper. After the toner has been transferred to the paper, the paper goes through a fuser unit. The fuser uses high heat and pressure to melt the plastic components of the toner powder, thus firmly bonding it to the fibers of the paper substrate. As the paper cools, the toner hardens to form a permanent print on the paper.

Now, when it comes to digital printing presses that use toner, the issue with heavy coverage revolves around how thick of a toner layer the fuser unit can melt effectively. Whereas the maximum ink application is around 300% for offset printing, the recommended maximum for digital printing is around 260%.

A Summary of things to keep in mind about Heavy Coverage

• When used wisely, heavy ink coverage can provide deeper colors and a richer appearance.
  
  
• The more ink a print project will consume, the higher its potential production cost.
  
  
• The denser the ink coverage, the longer it will take for liquid inks to dry and the more challenging it will be for toner to fuse properly.
  
  
• Projects with heavy ink coverage, especially when one solid color is used, will make any scuffs or wear marks more noticeable than they would be on projects with light or medium ink coverage. For this reason, a clear top coat is often recommended to add a layer of protection to the ink.
  
  
• When printing digitally, a heavy layer of toner can be prone to cracking along a fold line. This is because the toner is fused to the surface of the paper instead of being absorbed into the paper like a liquid ink. Pre-scoring the fold line can often alleviate this issue somewhat but it is still important to be aware of the potential for cracking.
  
  

Understanding how heavy coverage affects the printing process helps you make better decisions about your print jobs.

So if you plan to use heavy ink coverage on an upcoming print project, be sure to talk things over with your chosen printer as early in the design process as possible. Their professional insight and recommendations will go a long way toward ensuring the success of your project.

Color Vision is always happy to answer your Printing Questions

Whether you are looking to produce books, catalogs, brochures, posters, or any other type of print project, heavy ink coverage can create visually impactful results.

That said, this article addressed some important factors about heavy coverage to help ensure your use of this technique is a success. So whether you are planning to use offset or digital production, give Color Vision a call at 800-543-6299 with any remaining questions you may have.

Or, if you already know your project's specifications and are looking for a price quote, complete our Quote Request form and we will be happy to prepare a custom a quote for you.

As always, we look forward to assisting with your printing, binding, and finishing needs!