Printing signage on vinyl can allow your message to come through even with the worst that Mother Nature will throw at it.
In fact, printing on vinyl media can make it last for a while but requires special materials and expertise to do it right. Be warned: Working with vinyl is a lot more involved than wide-format printing on paper or fabric, so be patient.
One word: plastics
Vinyl (or more correctly, polyvinyl chloride) is a plastic that has been around for decades and is used for everything from shoes to raincoats. The key is that the material has excellent flexibility, impermeability and ruggedness that add up to making it the perfect media for printed outdoor applications.
It's a double-edged sword, though, because conventional inks don't readily stick to its surface, making a long-lasting image as much art as science. There are two approaches to coaxing the ink to adhere to the vinyl media: solvent-based or aqueous latex inks. Each has its pros and cons.
- Solvent formulations work by slightly melting the vinyl surface to allow the ink to seep in but can be dangerous.
- Latex ink forms a tight bond with the surface, although it doesn't weather as well as solvent inks.
Using a solvent-based ink is a time-honored technique. The ink's solvent carrier allows the colored inks to seep into the vinyl media's surface and stay there. This not only makes for a good image but great weather resistance with output often lasting for years without significant color shifts, fading or peeling. The top choice for items that must live outdoors, this printing technique is used for everything from parking lot signage to vehicle wrap ads to window graphics.
On the other hand, the solvent-based inks give off copious amounts of volatile organic compounds that can be flammable and are dangerous for technicians to breathe. As a result, solvent-based printers often have elaborate ventilation systems that can add thousands of dollars to an already expensive printer and require maintenance costs over its lifetime.
Kinder and gentler ink
Enter the latest eco-solvent formulations, which use a mixture of several less-severe solvents. Together, they have the same effect on the vinyl substrate, penetrating its surface to allow the ink to soak in and set up.
Take Roland's VersaUV LEC-540, a 54-inch wide printer, which uses the company's ECO-UV family of ink formulations based on acrylate solvents instead of harsh glycol ethers. The printer can work with five inks at once, including black, cyan, magenta, yellow and white. There's also a clear coating for resistance to the sun's ultraviolet (UV) rays.
Its nozzles spray at up to 1,440-dpi per inch resolution, but the printer's work isn't done. The wet image needs to be cured using a bank of ultraviolet LED lamps, hardening the ink so it won't smudge or run.
Because of this two-step process, the VersaUV LEC-540 is a slowpoke. Roland rates the LEC-540 at 113 square foot per hour, roughly the equivalent of about 19 D-size (24 x 36-inch) prints an hour. The 54-inch wide printer sells for $55,000 but can easily pay for itself with a wide variety of output, such as outdoor banners and posters and prototype packaging printed on foil.
The more recent alternative is to use water-based latex inks that are much more benign. They owe a lot to indoor latex paint formulations, are available in a great variety of colors and form a strong bond to the vinyl surface. Because they are based on water, they are safer to use with no danger of fire or explosion, aren't dangerous to the printing personnel and don't require curing.
In contrast to solvent inks, they don't weather nearly as well. While solvent banners and posters might have a usable lifetime of years, latex-printed items are measured in weeks or months. The usable life can be extended by adding a protective top coat.
A prime example of this genre is HP's Latex 365, which can use media of up 64 inches wide. Able to lay down images of up to 1,200-dpi resolution, its print engine's 2,112 nozzles create dots that can be as small as 6 picoliters of ink.
Able to work with seven ink cartridges that spray black, cyan, light cyan, magenta, light magenta and yellow, the Latex 365 also has a special latex optimizer coating that can sharpen the output and make it more weather resistant.
Because there's no curing step to slow it down, the Latex 365 can pump out banners, posters and other items at the rate of 250 square feet per hour, according to HP. That's more than 40, 24 x 36-inch, D-size prints. The device costs $17,000 and doesn't need special ventilation or drying apparatus.
Which is best to use? It depends on how long your company wants the printed items to be out in the open. Basically, a factory banner or window sign that's meant to remain in place for years should be made using the solvent-based ink approach, or you might find yourself reprinting and replacing it several times.
On the other hand, if it's for a short-lived film festival, sporting event or theatrical opening, it's probably easier, quicker and less expensive to make the items with latex-based ink, because the items only have to last a short time.