Large Format Printing by Derek Cooper

With the introduction of large format printers, many photo enthusiasts and semi-pros are looking at the feasibility of creating their own gallery images. PHOTONews asked Derek Cooper, of Reproducing Art, Kingston, Ontario, to explain some of the mysteries of printing large images in the home or studio environment.

Calibrating the creative process

With so many different cameras and monitors, the calibration of camera, computer, monitor, and printer is essential to creating a gallery quality print. How do you calibrate your system to achieve the best results?

I think the biggest misconception when it comes to printing is the concept of calibration, yet it plays the most crucial role. Calibration is the process of understanding the physical properties of the paper – how thick is it, how will it track through the printer, does the paper like a lot of ink, or is it a paper that really does not want a lot of ink? When most people think of calibration in my experience, they are really thinking of profiling, and jump to that step.

Let me explain.

Think of a paper you have just bought as a sponge. Some sponges have an amazing ability to absorb water, while others have a tough time soaking up the simplest of spills. But while we are not printing on sponges, paper is just a really thin sponge – you are trying to get the paper to absorb a liquid, in this case ink from the printer.

When we are looking at a new paper, the first step we will go through is to determine how much ink our paper is able to absorb. If the paper is able to absorb a lot of ink, then we know we have to supply a lot of ink to achieve the colours we want. However, if the paper does not like ink, then we have to reduce how much ink we try and put on the paper.

Think back to the sponge – once it is full of water, it can’t take anymore. But if you keep pouring more water on it, the water just starts to pool on the surface of the sponge. Paper is the same – too much ink will pool and even though you’re trying to get shades of black, you just end up getting pooling the ink on the surface of your paper, and your ability to generate shadows will forever elude you.

Just in case you think you’ve got the sponge figured out, how much absorption you will get is also impacted by environmental conditions, specifically relative humidity. In the middle of winter, the air is very dry, so your paper will also be very dry. In the middle of summer, it is very humid, so your paper will be “wet,” as a result. I guarantee your paper in the middle of summer will not be able to absorb as much ink as your paper in the middle of the winter – because it is already holding a lot of water that is floating around in the air.

At Reproducing Art, we maintain a year-round humidity level so we always know how much ink our papers are able to absorb. The next step in the process is to determine how thick the paper is and how it tracks through the printer.

If the paper is thick, then the print head could be closer to the paper than it should be. You’ll have to determine what platen gap setting is ideal for your new paper. Not sure if your paper is thick or thin – no worries. Your printer will have a nice paper thickness tool. Put in a sheet of your paper and run the printer’s paper thickness routine. It will typically print a series of lines, each one a little different from the line before it. Your job is to determine, typically with a loupe, which line is closest to being a line, and which ones are not quite aligned.

Now for tracking. Each paper will move through your printer at different rates. If too much paper feeds through, you’ll get white lines horizontally across your prints. If not enough paper feeds through, you’ll get overlapping, which is visible by dark horizontal lines.

Once we adjust the platen gap, we feed one metre of paper through the printer. The printer will print one long line for what it “thinks,” is one metre. We then measure the length of the line and find that not surprisingly, it isn’t one metre in length. It’s either a little longer or a little shorter. We then adjust the tracking based on our findings.

Of the photo enthusiasts I have met who print at home, 95% have never considered the above calibration steps – they skip ahead to profiling, my next topic.

What you see is not always what you get!

Profiling is the process of determining what colour the printer thinks it is printing versus what colour is actually printed. Similar to the process of profiling your monitor, you print a series of colour boxes and then scan those boxes using a colour meter. Each colour box is read, and then the software that runs the meter calculates the difference between the colour that was sent to the printer and the actual colour, and then makes a mathematical adjustment. You then print using the profile and the colours should be more accurate after a few iterations.

Your monitor is your key link between what you see on-screen and what you see in print. Computer monitors all interpret colours differently. By profiling your monitor, you have a better chance of ensuring the colour of the grass you are seeing is actually the colour of the grass that is being sent to the monitor.

But of course, there is more – brightness. Too many monitors that are sold today are much too bright for printing. The result – your prints look dark and the colours are dull. The solution – reduce the brightness of the monitor. From my experience, most monitors are roughly 50% too bright by default.

How long does it take to establish a baseline for accurate prints?
At Reproducing Art, our system calibration and profiling is very refined, almost to the point of bypass the proofing stage when printing for clients. But we control everything – ambient lighting when viewing images on-screen, humidity in the printing area, and tight calibration and profiling of our papers and canvases.

When we calibrate and profile a new paper, a number of the papers do not pass our initial tests. For those that do, we typically spend 10 hours fully calibrating and profiling each paper.

For the hobbyist, is it feasible to make large prints in the home studio?

It comes down to expectations. If close is good enough, then it is possible. But if you are more discerning, it can be a very frustrating and expensive venture. Few people would be willing to climate control their printing environment. Fewer would be willing to invest in the hardware and software required to properly linearize and profile one or more papers. And then there are the costs of using the paper and ink to calibrate and build paper profiles. Expect to consume a significant volume of ink and many feet of paper in the process.

If you purchase a lower quality paper, you are dealing with quality control issues from the manufacturer – paper from the same manufacturer can vary from batch to batch. So the green grass on one print may not look like the same green grass on the same paper from the next batch.

How often does the printer have to be cleaned? Is there a recommended maintenance procedure?

Two answers – as little as possible and carefully.
It is important to avoid the temptation to continually run the printer’s self-cleaning. It consumes ink and often creates more problems than solving the one you’re experiencing. Only run the self-cleaning when it’s clear you have one of the printer jets clogged, and if possible, only clean the one jet – some printers will allow you to select the colour you’d like to clean.

When it comes to physically cleaning the printer, do it carefully. Do not use compressed air to blow the dirt off surfaces. Chances are you’ll just force the dirt into recessed areas around the print head. Use a vacuum and suck the dirt out. To reduce the dirt in the first place, try and avoid using the printer’s built-in cutter, depending on the printer model. The cutter ejects tiny paper fibers into the printer. If you are printing on a paper roll, keep a set of scissors handy near the printer and cut the paper that way. You can trim the roll on a large rotary cutter after.

Paper and Ink

With so many choices in paper, how do you select the appropriate medium for a series of images?

Work with vendors who have been in the industry a long time and have a record of producing the same paper for a period of time. Making paper is non-trivial, and if you go through the process of calibrating and profiling paper for your own use, you want to know that batch to batch the paper is consistent and that the vendor will continue to sell the paper for a long time.

At Reproducing Art, we do not believe in having a huge selection of paper, but rather the best in each category. We then work with the artist to understand their intended style and match that to the inventory of papers and canvases we work with on a daily basis.

We have had excellent results with a range of Hahnemühle papers. The company has been producing fine papers since 1584 – that is more than 425 years of experience!

How long does it take for a print to “dry” before it can be framed?
Drying can have many meanings. When building paper profiles, you want to be consistent in the amount of time you allow the colour blocks to dry, so you’re always measuring at the same interval. We recommend 20 minutes from printing to profiling. However, we have some papers that take a much longer time to “setup,” some as long as 1 hour. So it varies – like most things in printing. For framing, we typically wait at least 12 hours, especially for canvas jobs. We want to make sure the ink has fully dried before we apply a varnish top-coat.

Archival printing

Colour shifts and fading are factors that will eventually affect any image. How do you select the inks that will deliver the best long-term performance?

We choose to work with companies that provide proven expertise and access to their technical teams when choosing inks. We run into scenarios with some clients who want to use a different mounting or framing technique, and we need access to the vendor’s technical staff to discuss the implications of what is being proposed.

Framing and display

In the days of darkroom printing, we used to coat the prints with UV protectants and in some cases, texture and special effect finishes. Are these types of products available for the ink jet prints?

Absolutely. For canvas jobs, we always apply a varnish top-coat using a high volume low pressure spray system in a walk-in booth. For paper prints, the only time we use a coating is when we are preparing high-end portfolio books that use double-sided papers.

How critical is the placement of a gallery print relative to light sources?

Very critical. All inks will react to artificial light differently than they do to natural sunlight. The most common ink, pigment, will react differently in fluorescent light than incadescent light or natural light coming in through the window. At Reproducing Art, we assume all our work is being viewed at 5,000 Kelvin, or daylight. It would be impossible to profile our papers for the great variety of viewing conditions available in the natural world.

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