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Paper Curl and (those dreaded) Print Head Strikes

Written by Les Picker
Photography by Robert Boyer
 

Fine art printing today is far easier than even a decade ago. Still, newbies have a slew of things to think about as they climb the learning curve and gain experience. Color management, paper selection, printer dialogues, you name it and it's another item on the way to fine art printing mastery.

But how many of us think about the importance of flat paper? What does one do when fine art cut-sheet paper curls? Here I'm talking about curls that happen in boxes of sheet paper, not the curling that happens at the end of a roll of fine art roll paper (that's a separate discussion… stay tuned). This may sound like a trivial matter if you are new to printing, but when your print heads start striking those curled sheet edges, you'll be seeing dollar signs - big ones - popping up.

As a Moab Master, I thought I'd do a quick scan of some of my fellow Moab Masters to see how they handle keeping cut sheet paper flat. I also wanted to hear from the folks at Moab on how they take paper curl into consideration at the paper design and manufacturing stages.

Some Background

“What some people may not realize is that all paper is initially produced on a roll,” explains Marc Schotland, VP, Marketing for Legion Paper. “The curl is caused by the natural formation of the fibers pressed against the core of the roll.”

Once these jumbo rolls are produced, they are sent off to be coated. When the paper is coated, an anti-curl back-coat is applied to counteract the coated/printed side. These now-coated jumbo rolls are then sent off to be converted into sheets and mini-rolls (those 17”, 24” 44”, etc…).

“Obviously, the paper closest to the core will exhibit the most persistent curl memory,” Schotland continues. “But those sheets from the roll flatten over time as they are laid out on a flat surface so that the fibers will 'relax’ and modify their formation to match the flat surface”.

The problem arises when paper is kept unsealed in extreme humid conditions or fluctuating temperatures. The fibers will change formation again, sometimes even buckling if enough moisture gets into the paper.

Notes From the Real World

As a working pro myself, our studio sometimes experiences cut-sheet paper curl. We tend to go through our paper stock fairly quickly, between prints for clients and our fine art printing workshops, which minimizes the chance of curl.

Although we try to follow preventive measures to reduce curl, we're not always perfect. My assistant or I will leave a box opened overnight, or we will take out 10 sheets, only print five and then find the rest, slightly curled, two weeks later!

"In my experience, curl seems to happen with glossy and luster papers more than matte finished papers," says Jim Graham (www.jimgrahamphotography.com), a Moab Master and well-known East coast master photographer. I would agree with Jim. I have yet to have an issue with curl in matte papers even though they, too, are coated. But whatever the paper type, sheet curl can be frustrating, especially when you are under pressure to get a print done."

An Ounce of Prevention…

Based on this foray into paper curling in the box, here are some suggestions from my fellow Moab Masters, and from Moab itself, for how to keep paper flat.

“Always store paper horizontally, not vertically,” suggests Evan Parker, Moab Support Specialist.

Keep paper in the original plastic bag, in the original box. In our studio we also tape the plastic bag to seal it from the elements when not in use.

If you cannot remove the curl, use the platen gap settings on your printer to widen the gap between print heads and paper.

“Store your paper in a humidity-stable environment, out of direct sunlight, and away from heat or a/c registers,” Parker also suggests.

On some of our larger cut sheet papers, 13“x 19” and above, I also add a handy desiccator tin to the box or bag that the paper is stored in (available online). When the desiccator captures all the humidity it can, just pop it in a 300-degree oven for 3 hours (a toaster oven works great!).

… And a Pound of Cure

Even the best preventive program sometimes fails. What do the pros do when that happens?

“If it's just minor curl, I simply will invert the paper in the box and let its own weight flatten it,” Jim Graham tells us. “If it's a major curling issue I'll sandwich the paper, wrapped in archival paper, between books. And let the pressure of the books and their weight flatten out the curl.”

Moab's Evan Parker suggests we let the sheet sit out in our printing environment for 30–60 minutes to see if an environmental adjustment resolves the curl.

In our studio we'll try gently reversing the curl with cotton-gloved hands, so as to prevent oils from our hands from contaminating the paper. On occasion I use a tissue-paper covered empty paper tube to get the job done. Gentle is the operative word here.

“I load each sheet individually into the printer with the flattest edge going down into the printer first,” explains Harold Davis (www.digitalfieldguide.com), a Moab Master from the West coast. “If the printhead seems to be striking one of the side edges of the paper, I'm not beyond opening up the printer door, which stops the printhead in its tracks, and gently smoothing the paper down. Then I'll close the print door, and printing will resume automatically.”

Still, no matter the printing challenge, we all know the value, and classic beauty, of the printed image. Moab Master Harold Davis summed it up best: “Sure, paper curl is a fact of life. But there's nothing like making hand-crafted, artisanal prints for satisfaction with one's work. Even though it is a digital world, you still make prints one-by-one, with one-off attention to sheet curl and many other issues.”

Les Picker is a Moab Master from Maryland. You can follow Les' blogs from his website: www.lesterpickerphoto.com