How Temperature and Humidity Affect Digital Printing

By | August 6, 2010

A few weeks ago I worked on an assignment with a paper supplier who starting offering digital printing on their custom papers. When I walked through the door of their production facility I felt as though I walked into a wall of heat and humidity. It was about 90 degrees and 90% humidity.

The great surprise was that they knew that temperature and humidity affected their paper so they kept them in temperature controlled rooms, but they must not have realized the issues that heat and humidity created in digital print production. This reminded me of the first time I learned the effects of temperature and humidity on paper. I was sitting in a classroom at GATF (Graphic Arts Technical Foundation) in the orientation class as a new staff person.

Working for GATF was a great experience because it was all about education. When I was hired I was the youngest consultant on staff compared to people who had 20 or 30 years of experience almost all in the pressroom. I was brought on as the “digital guy.” Most of the courses at GATF were team taught so I would talk about “digital stuff” and sit in during the other presentations. This is where I learned about the color, scanning, offset printing and paper.

It was during these presentations that I learned about the role that paper plays in both offset and digital printing. Like any newbie I had no idea that moisture in paper was important in print production. I was fascinated by the discussion of how paper absorbs moisture from the air like a sponge and it is called moisture content. I remember the questions we were asked in class. Why do we have wavy paper in the summer? Why do we have static in the winter? Why do we fight curl year-round?

Best Printing is at Comfortable Conditions

Of course now I know all about the issues of humidity and moisture content. The moisture content of a print shop is measured as relative humidity and it affects the amount of moisture in paper. Typical paper is produced to an absolute moisture content between 4.0 and 6.0%, meaning 4 to 6% of the paper’s total weight is made up of water. But once unpacked the paper can either absorb or dissipate moisture. In the best conditions the paper is designed to be stable in a 45-55% relative humidity (RH) at 72°F environment.

The key is making sure you purchase and use the right paper for the right use and maintain stable conditions which are close to those recommended. Different printing processes work best with certain amounts of moisture. In digital printing the moisture content can affect the toner adhesion, paper jams and the fuser roller temperature. In offset it can affect the interaction between the ink and the press, the paper and the press, and the ink and paper. Inkjet is affected by many of the same issues but is even more susceptible to dot gain or ink spreading, drying delays and ink show through.

On this assignment the focus was inkjet printing. There is a tremendous amount of new product development with inkjet papers because of the focus on inkjet presses. But in general inkjet paper is optimized for ink absorbency, color development, water resistance, light resistance, gas resistance, and run ability. The problem was that printing at 90 degrees and 90% humidity is troublesome for most digital printing processes.

Have you run into any issues when the temperature and humidity is too high in the summer or too low in the winter?

Howard Fenton is a Senior Consultant at NAPL. Howie advises commercial printers, in-plants, and manufacturers on workflow management, operations, digital services, and customer research.

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3 thoughts on “How Temperature and Humidity Affect Digital Printing

  1. Heidi Tolliver-Nigro

    Howie, were the owners of this facility printers? Or were they entrepreneurs? As the number of “marketing services providers” / digital print shops grows, I think we have to remember that many of these guys are NOT printers initially. They are business owners. This is great for marketing and business development, but as you say, they probably have no idea how environmental conditions affect their production. It’s great that we are shops so focused on business development, but even as digital print shops move toward marketing expertise, we do have to remember that digital printing is still a production process, too.

  2. Howie Fenton

    Thanks Heidi

    You are spot on. This company is not a traditional manufacturer, it is owned by a business person. Like most companies they are great at 2/3 of the most important functions. For them it is financial management and marketing but not production (this article in Print CEO talks more about this And this Friday I talk more about this subject in an article called “Paper, Production Issues and Solutions”.

  3. Eddy Hagen

    Relative humidity and temperature control might be one those issues in a printing company (both traditional and digital) that almost nobody knows about, but that can have a big influence on the production. I know very few printers that have control systems for both.

    A few examples of companies I know, I’ve visited:
    * one is working within extremely tight tolerances, less than a delta E of 1 (they are in very specific and demanding niche). But they had color issues, to get reprints exactly the same as previous orders (almost all of their orders are reprints). When I walked around in the print shop, I saw that all the doors were open… “Yes, we have to do that, otherwise it gets too hot in here.” It was summer, the outside air was also quite hot and very dry…
    * another one is also dealing with a lot of reprints (but not that tight tolerances as the previous example). They deal with many ‘professional print buyers’ who are very picky on color. So from time to time they get complaints that a new production run doesn’t resembly the old one close enough. Next to more obvious variables in the printing process: in winter time they print at 15°C (59°F), in summer time sometimes even over 30°C (86°F).

    There is an interesting anecdote about a public benchmark of different proofing solutions a few years ago (I forgot the name of the event). Multiple vendors had their systems installed in a conference room and had x time to set up their systems and print several test files. For one of the vendors it didn’t work… they could not get their system right. What happened? Their printer was standing too close to the window, and the sun was shining…

    Having a relative humidity control / temperature control (aka: airconditioning) in a press room, in a print room is expensive, I know. But it will definitely get your production more stable. Which eventually will pay for the system (less setup waste, less rejected jobs). I know a few printers who have invested in it and they all love it! And one extra advantage: it’s also more comfortable for the press operators…

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