High-Speed Aqueous Inkjet: Excuse Me, But You’re Bleeding...

Oh, Mother Nature, how you have been upset with us this year. From the harsh winter to the rainy East Coast and Midwest, you have caused havoc for some inkjet printers.

This year, more than ever, I’ve heard about printers having issues with the water resistance of prints produced on their high-speed aqueous inkjet printers. Printing companies are hearing from their customers that the ink on the bills and statements, when received in the mail, are bleeding, wicking and offsetting to other mail, or are totally illegible.

Printed bills and transactional statements represent a very large percentage of the high-speed inkjet market. When there are complaints about the ink bleeding, smearing and becoming illegible, it causes great concerns for all. This is not a good thing for anyone.

But, before you start blaming Mother Nature for such issues, note that, while she may be the cause, it’s not the reason.

We must remember the inks typically used for transactional and billing inkjet printing are mostly aqueous dye inks. Note the word “aqueous.” This means water. Ninety to 95 percent of the ink is water, and the rest is dye and other chemistry, which allows the ink to jet correctly from the print head. Most often, since transactional printing costs must stay low, printers typically opt for a plain, inexpensive, uncoated sheet. These sheets have absolutely no chemistry to “fix” the dye to the fibers. Without a “fix,” the dye will “rewet,” run, bleed, wick and dive through the sheet—causing this messy situation.

Aqueous pigment inks are not often used for billing and statements because the ink is currently more costly than dye inks. Pigment inks tend to be more water-resistant than dye; they don’t apt to bleed and wick, but can rub off easily when areas become saturated.

To help combat such issues, suppliers will tell you to try a treated sheet. Treated sheets have a chemistry that help keep more of the dye colorant on the surface of the paper. But, very few treated sheets are truly water-resistant (some are better than others). It really has to do with the quantity, duration and prolonged exposure to moisture. We continually test various treated paper grades in our lab to see the extent of moisture that a printed sheet can handle. And one surprising feature we find on treated paper, which claims to be water-resistant, is that some ink colors tend to bind better to the treated paper surface chemistry than others. When a print rewets, what bleeds sometimes is caused by the combination of ink colors printed.