Man is Meant to Act and Not be Acted Upon

Most people who purchase their first wide-format printer have absolutely no idea which ink process is best for their purposes.  Wide format printers use aqueous, UV-cured, latex, resin, full-solvent, mild-solvent, eco-solvent, or dye sublimation inks; and each has its pros and cons.  More than this, the prices can range from $5,000 to $500,000.  So, like the Octomom, I’m going to try to explain which one’s which.

First off, there is no right answer.  A professional sign shop may have multiple instances of each of these types of processes, for different purposes.  If you only want one, you’ll have to decide what type of printing you’re hoping to do with it – where the demand is that you can fill.  Do you want to go after art reproductions, retail stores, schools, color blueprints, portraits, wallpaper, billboards, packaging, magnets, CAD renderings, aerial photographs, car dealerships, malls, trade show graphics?  Our guy does motorcycle wraps for the races at Infineon Raceway, while I personally love to ram through as many substrates as I can get away with—I ended up building a strange little niche printing fine art onto chit-board.

Since it’s not about ink, we won’t even mention the hugely important workflow compatibility factors: Mac vs. PC, Postscript vs PCL, Pantone certifications, etc.

Aqueous / Water-based Inks: This is by far the most popular type of machine—basically a desk inkjet, but 24”-104” wide.  They are cheap, can normally print up to 2400 dpi, and print gorgeous posters and signs.  These machines can print on a very wide variety of materials, including uncoated and textured papers.  Inkjet on canvas is what is called “giclée.”  Because the machines are so common, the inks are cheap per square foot and generics are readily available.  Aqueous inks do not smell as pungently as the rest of the inks, which we’ll discuss later.

The primary negative about this type of ink is that it’s not very durable.  Like an desk inkjet, the ink is laid on top of the substrate and dries through evaporation, without external heat.  The ink may permeate enough to blur the image or warp a light paper, but not enough to be entirely scratch resistant or water-resistant.  I’ve printed banners on these machines and sprayed them with hoses and never seen one smear without physical friction.  In my experience a banner can sit out in the rain for months and not smear, as long as nothing touches it—not a branch, not a thumb, not the corner of the banner flapping against itself in the wind.

The gamut of these inks is wide, especially on coated papers.  Colors will be less vivid on vinyl.  Resolution is always a misleading number.  Every type of ink is capable of printing at a far higher resolution than the human eye can perceive, but the higher stated resolutions will yield larger color gamuts, deeper blacks, etc.

Aqueous inks are perfect for short run architectural and CAD renderings, artistic paintings or portraits/giclées, various fabrics, menus, board games, book covers, jigsaw puzzles, custom seat upholsteries, family portraits, theater scenery and backdrops, proofs and imposition proofs.  Even custom wrapping paper can be a viable part of your shop’s menu with an aqueous printer.

Most of all, aqueous printers carry a high profit margin.  On most of my prints I’m running at $1.50-$2.00/sq. ft. and charging $5.00-10.00 per square foot.  That means a typical 3’x8’ banner will run me $40 to print and can be casually sold for $160.  So on a $6000 aqueous printer, you’ve paid off the machine in less than 100 jobs.

Solvent-based Inks:  This is normally the second machine a shop purchases.  It has most of the benefits of an aqueous printer, without the main drawback of being susceptible to weather or abrasion.  Solvent inks produce waterproof banners, posters that can be cleaned, billboards, building wraps, backlit signs, awnings, and most of the other products that an aqueous ink can produce; albeit with a slightly lower gamut, a lower resolution, and with a much more expensive machine.

Solvent inks come in a few flavors: full-solvent, mild-solvent, and eco-solvent.  The main and almost only difference between the three is the pungency.  If you’re planning on installing a wide-format printer in a specific location, the size and ventilation level of that location may be a major factor in choosing which type of machine to purchase.  Full-solvent ink yields the best colors and the most durable prints of the solvent inks.  The solvent process first involves a heating phase to “open the pores” of the substrate.  Then the solvent-based ink is laid down.  In a sense this is the opposite of a commercial for a stain-busting laundry detergent.  After the solvent/ink penetrates the medium, a second heat cycle evaporates the solvent, leaving the permeated pigment.  This, however, is where the VOCs manifest.  VOCs means carcinogenic and gene-mutating vapors, and that’s what you’ll be smelling.  (They’re no different than the solvents already in your pressroom, but if you’re like me, you already get a lot of complaints about those.)  Eco-solvents aren’t necessarily more environmentally friendly per se, but have less VOCs.  They work basically the same, but smell less.  However, having less solvent means the ink won’t permeate as deeply nor as tenaciously—therefore the colors won’t be as vivid, and the end product won’t be as durable.  To solve that problem the market came up with a third and currently most popular solvent-based option, mild-solvent ink.  Mild-solvent ink is exactly what it sounds like—it simply has a wider gamut and yields more durable prints than eco-solvent ink, but smells less than full-solvent inks.

Relative to the amount of solvent used, banners produced in a solvent process will “outgas” for days or weeks.  So it’s not just whether your building has sufficient ventilation for your employees and the customers in the sales room.  It’s also whether your customers are the sort who will notice banners that potentially smell.  Because of the nature of solvents, you can only use strong, coated substrates.  As such solvent inks are not ideal for photos, maps, blueprints, etc., which may be an important part of your business.  This is especially true with eco-solvent inks, which normally require specialized coated papers.  The ink itself is cheaper per bottle than the other options, but more expensive per square foot than UV-cured inks.  Many analysts expect mild-solvent and eco-solvent inks to be gone within five years, replaced by latex inks or UV-cured inks.

While solvent-ink systems are becoming less prohibitive to purchase, they won’t generally be able to charge any more per square foot than an aqueous process.  They will, however, cost less per square foot to print.  Still, you’ll be trying to recoup $60,000 in sunk costs in exchange for smear-resistance.

UV-cured Inks:  UV-cured inks are one of the competitors to eventually replace solvent inks, but in the meantime, has some weaknesses that make it prohibitive except for specialized uses.  The primary use is in a flatbed printer on solid materials.  UV-curing printers are used to print directly onto any perfectly flat surface, a synthetic door, a laminate, an acrylic sign.  This method is even more durable, and therefore requires even more heat (and therefore even more electricity.)  This will decrease quickly as LED processes become mainstream.  LED allows for heat sensitive materials, but is still having problems with adhesion (not having the heat.)  Otherwise, with full-heat the adhesion is strong enough that UV-cured inks rarely need laminating.

First and foremost, UV-curing cannot print on anything that is not perfectly flat—meaning no cloths, no textures.  It can print on uncoated papers, but may be prone to wrinkling.  The bulk of museum art uses aqueous inks, but an increasing proportion is being printed using UV-cured inks, because the paintings can be reproduced with a very high resolution and directly onto a firm, textured substrate (if such is preferable.)  UV-cured ink prints are more scratch-resistant than solvent-based inks (which, as you may recall, are significantly more scratch-resistant than aqueous inks.)  Despite their scratch resistance, multiple users have reported UV inks as chipping when cut.

Resolution with UV inks can be high; however colors are less consistent than with solvent inks (and better still on aqueous inks.)  UV inks tend to push your reds into magenta territory, your yellows into green.  UV absolutely wins with those hard-to-hit metallic colors, and with white.  If you need a white channel, UV inks are the only ones opaque enough to make you happy.

UV inks still smell, just not as bad as solvent.  UV ink is not only more expensive, but you need to clean the machine when refilling the ink—rather than just dumping more in the top as with solvent printers.  UV processes will also requires significant cleaning time, with dramatically lower tolerances for dust and fingerprints.  For this reason, this process is untenable for short runs.

UV-cured inks produce durable prints.  Whereas water-based inks are susceptible to water; UV ink should only fade when exposed to UV light—which means in real world conditions, it is extremely durable.  All things being equal, UV inks don’t cure as long, and therefore are popular for vehicle wraps.

Latex-based: Latex ink is only made by HP, and isn’t fully evolved yet.  However, there’s a lot of continuing hype about it, and latex ink or perhaps another resin-based ink is expected by many to eventually replace the light-solvents.  For one, Latex ink processes don’t stink!  Existing latex-ink printers use a wide enough swatch that the printing is dramatically faster.  It is very durable—it can also print on Tyvek!  Completely dry off the machine, it has become popular for vehicle wraps (solvent needs to cure for at least a few hours before mounting, and still smells for a week.)  It can also be immediately laminated, although the adhesion is so strong that lamination is rarely used.  Less VOCs should facilitate environmental certifications and marketing.

The biggest downside is that latex only adheres to premium coated papers at this point.  As always, that may be fine, and depends on your market research relevant to your customer base (but I couldn’t get away with it.)  It currently only exists in a roll-to-roll formation.  The gamut isn’t fully evolved yet, meaning the reds tend toward orange, the blues can be hyper-vibrant, and many reports say the blacks aren’t rich enough.  This may not be a problem if you’re serious enough to write your own ICC profiles, but for most people looking to upgrade from a aqueous or eco-solvent printer, that idea won’t excite you.

While HP understands that fostering generic inks and printers are an important part of pushing a new standard, none have entered the market significantly yet.  Having no generics, the absolute costs are high (but the variable costs of the ink are the same as solvent, and with generics should eventually be lower.)  And, memorably, melting the tiny drops of latex onto the paper requires the heating stage hover at close to 200 degrees (twice as high as the others.)  For many people, unless you have a good A/C, latex is simply off the table.

Overall, you should keep an eye on latex as it is a great next-gen technology.

Dye-sublimation Inks: Like UV-cured inks, dye-sublimation inks serve a very specific purpose which may or may not apply to you.  Dye-sublimation is the process of zapping the ink from solid to gas to solid without going through a liquid phase.  Science aside, it’s only used for specific high-adhesion purposes, especially those when a laminate is preferred (because there’s normally no black channel, instead replaced by a thin laminate.)  Dye-sublimation inks have a high enough adhesion that jobs printed on cloth can be put in the washing machine.  A lack of a black channel doesn’t mean the black won’t show up richly, but that all blacks have to be rich (made up of a combination of the remaining CMY).  That simply takes a lot of ink.

Ideal uses for dye-sublimation ink include wallpaper, murals, towel, kitchen tiles, table cloths, laminates for counter tops, ties, magnets, or those giant “coming soon” building wraps at the mall.  A lot of these jobs would have previously gone onto an inefficient and smelly screen printing machine.  And yes, a lot of these uses overlap with the UV-cured inks.  Remember, however, that UV-cured anything needs to be perfectly flat.  Another important distinction from UV-inks is that dye sublimation is the only process that can handle unprimed glass—UV prints on flat things, but flat does not necessarily mean slippery.  Dye-sublimation inks and their correlative equipment carry the most expensive absolute costs and often the cheapest variable costs.

“Primed” can mean a lot of things.  With each type of ink, it involves some form of heating the substrate to open its pores, or adding some layer of ink-receiving chemical in advance.  As mentioned earlier, the more durable your prints, the hotter your machine will generally be—which may be a huge factor depending on the size and traffic of your shop.  UV printers can actually handle glass, but glass that has been treated, so it’s up to you whether it’s worth adding to your menu.

Bottom line, your main factor in choosing a wide format ink type should be what you intend to use it for.  Aqueous printers are normally where shops start, and probably where they should, since they produce consistent, short run, high resolution prints on a variety of substrates and at a low cost.  They also have a huge profit margin!  Solvent printers are the next step up, and a good entry point if you’re willing to commit a bit more money up front, your customers have expressed an interest in water-resistant printing, and you have good ventilation in your production facility.  This allows you to get into the outdoor banner space.  UV-printers are neat, but normally only used for printing on solid substrates, at consistent volumes, and in clean facilities.  Latex is probably where you want to go when you outgrow solvent, but that’ll probably be a few years.  And dye sublimation is amazing for specialty products at high volumes.  If you don’t know where to start, start with Aqueous until you understand your market.

Tags: Business, Equipment and Supplies, Infineon Raceway, Light-emitting diode, Printing, Publishing and Printing, Ultraviolet, Volatile organic compound