Basic Guide to Digital Printing-Part Two

In Part One of the Basic Guide to Digital Printing, we talked about ink options. If you’re shopping for a new printer, the first consideration should be what kind of ink is best for your applications. Once you’ve made this decision and purchased your printer, you need to be wary of the most common mistakes made by sign and graphics professionals new to digital printing. These involve color space, file size, finishing, and maintenance. Understanding these topics will greatly reduce your learning curve and make your first printer much more productive and profitable.

Color Space

After picking your ink and printer, you may be confronted with some basic limitations, especially if you’re coming from a screen print or vinyl graphics background. In screen printing or vinyl graphics, you pick the colors by selecting an ink or vinyl, then apply them one at a time. What you see is what you get. With digital printing, it’s more of a Porgie & Bess situation; it ain’t necessarily so. The colors you see on your monitor when designing a graphic aren’t generated the same way as those that come from your printer. The monitor and printer operate in two different color spaces. Fortunately, they’re not completely different types with no common ground,  like cat-lovers and dog-lovers. Mostly, they overlap. But there are important differences that can cause unexpected shifts in your digital output. Reds and blues don’t look right and the new printer usually gets the blame.   Click here to get the full story on why this happens and how to manage it.

Garbage In, Garbage Out

FIG 1: Enlarging a web graphic can result in poor large format image quality.

FIG 1: Enlarging a web graphic can result in poor large format image quality. Not enough data to support the larger size.

The other common mistake beginning printers make is to download an image from the internet and try to print it on a 3’x 8′ banner. Images that look good on your browser in a little 8″ x 12″ space will most likely look pixelated–aka crummy– when enlarged to a 24″ x 36″ image. The problem is data or rather the lack thereof. In order to produce images as quickly as we want our web browsers to work, the browser generally reduces the image to 72dpi and uses random compression to reduce the file size. The standard print resolution that sign industry customers find acceptable is 720 x 720 dpi. That’s ten times the amount of raw data as that found in a web graphic. Enlarging a compressed 72 dpi file to a large format 720×720 dpi print requires your RIP software to do a lot of guessing to fill in the gaps left by the missing data. The results are images that look fuzzy and distorted, as if the image isn’t quite in focus (FIG 1).

There are some applications that try to enlarge or ‘upres’ image files, like the SuperSize bitmap feature in our JetPRO software, but these digital tricks can’t always rescue a job doomed by a low quality image. Remember the old axiom; “garbage in, garbage out”. If you want good quality large format prints, you have to start with high quality image files. This will require educating your customers so they won’t expect you to produce a stunning vehicle wrap from a web graphic.  They may insist on the low quality image file, but if you warn them of the probable outcome, they’re less likely to hold you responsible for their bad decisions.

Lamination

Most professional sign or print shops have a laminator.  If you’re doing long-term outdoor signs, this may seem confusing because the solvent, eco-solvent, and Latex inks all make claims of three year outdoor durability without lamination.  So why add the equipment and material cost of laminating these prints? Simple. Those outdoor durability ratings, while generally valid, only apply to UV resistance, in vertical applications. They say nothing about what may happen to the print if it’s applied to a vehicle and subjected to detergents during washing. What happens to your floor graphics when it’s time to sweep and mop? Abrasion is the enemy of print durability. Lamination protects these UV-resistant prints from damage due to abrasion, detergents, and grimy fingers.

So if your prints will be outdoors, but not subject to detergents and handling, say a banner hung on the front of a building, or a backlit poster in a display case, lamination isn’t necessary. But for vehicle graphics, floor graphics, of anything else where the ink will be exposed to hands or cleaning agents, the extra protection is recommended.

Depending on your printer and ink combination, you may have to allow time for the ink to completely dry or out-gas before laminating. Rushing a solvent or eco-solvent print from the printer to the laminator can cause problems. Click here for more details on the out-gassing recommendations for these inks. For more on the types of lamination, including aqueous and solvent based clear coats, please click here.

Recommended Maintenance

FIG 2: Regular maintenance, like cleaning the print head, is key to keeping your printer running smoothly.

FIG 2: Regular maintenance, like cleaning the print head, is key to keeping your printer running smoothly.

Before you purchase a printer, make sure you know what the required maintenance will be. Different kinds and brands of inkjet printers require different amounts of maintenance to keep them clean and running smoothly. Generally speaking, the cleaner they are and the more frequently they’re used, the better your printer will work. Conversely, the people who use don’t clean or maintain their printers or who let them sit idle for weeks at a time are the ones most likely to need expensive repairs. Aside from the cost of having your equipment revived, the time required to get a clogged or dirty printer running again is often much more than it would have taken to keep it clean and running smoothly.

Having said that, there are some kinds of printers that require more or less maintenance. Printers with solvent based inks or white ink generally require more maintenance that aqueous or UV-curable inkjets or those with traditional CMYK color gamut. Solvent based inks need to be flowing in order to avoid settling and clogging. White ink is even more prone to clogging because of the Titantium Dioxide used to  provide the opacity. TiO2 is one of the heaviest pigments used in inkjet printing and, if the ink delivery system is left idle, it will fall out of solution and cause problems with clogged ink lines and print heads.

Most entry-level white ink-enabled printers require regular maintenance designed to prevent this. Sometimes it’s as simple as shaking the ink cartridges. Most advanced white ink-enabled printers  like the MUTOH ValueJet 1617H or Direct Color System 1024UVMVP have internal recirculation systems which keep the ink flowing even when the printer is idle. Metallic inks in inkjet printers have similar drawbacks. Some early adopters of these devices have been disappointed with the amount of maintenance required to keep the ink flowing. There are benefits to metallic ink, but if those are important to your product line, make sure you have the time and resources to service it properly.

Latex, UV and aqueous inks require less daily maintenance, but any inkjet printer left idle or neglected will malfunction. For our PrismJET VJ48 Plus, we recommend that, if the printer is idle, users should at least print a test pattern every three to five days to keep the system flowing. Please click here for a complete list of suggested maintenance for your PrismJET VJ48 or MUOTH ValueJet 1204. For PrismJET DTx maintenance, please refer to section 27 of your DTX User Manual.

Whatever type of ink you choose, or whatever brand of printer you own, do yourself a favor and make a commitment to learning and following the manufacturer’s recommended maintenance regimen. It will ensure years of productive and profitable use.  This is an especially important consideration if you lease the equipment. Stretching the cost of the equipment purchase out over several years is a common strategy that works for most businesses. But, if poor maintenance leads to equipment failure, you may find that your payments last longer than your printer.

So if you have yet to take the plunge, do your homework and choose the type of printer and ink type that best fits your intended applications. And once you’ve setup your new printer, make sure you know the limits of its color gamut and how to adapt it to your customer’s needs. Consider what kind of abrasion or UV protection be required. And most importantly, make the commitment up front to maintain your equipment so that your investment produces prints and profit for years to come.