Here’s a simple statement: digitally imaged signage is becoming ubiquitous in our society. Just ten years ago, much of the signage used for retail uses and other applications existed in a two-color world. For many signage applications, full color was just too expensive. Thanks to the rise of digital imaging technology, full color is now the norm. As inkjet ink systems have delivered color signage for indoor and outdoor applications on a wide variety of substrates, the range of possibility for signage application has continued to grow.
Stepping into digitally imaged signage markets may, for your company, be a step in a new direction. The purpose of this article is to give you some of the basic information and strategies you need to get started.
Equipment & Inks
The digital equipment used in businesses that produce signage varies, dependent upon the range of products manufactured. Let’s discuss inkjet-based solutions for digital sign production.
By far, the largest pool of inkjet printing devices in use today is aqueous based. These are water-based dye or pigment ink systems. They are best suited for indoor applications where the duration of use is not long term. Unprotected, these ink systems can be used to generate prints for indoor or limited outdoor use. For outdoor uses, or to increase durability of the print, the print must be laminated. Due to issues of cost and technology, most entry-level wide format printers use either dye or pigment inks. These printing devices can be found as roll to roll or in a flatbed configuration.
What is the technology difference between dyes and pigments? Dyes are molecules of colorant dissolved in a fluid, much like instant lemonade crystals dissolving into water. Dye-based inks fade more quickly than pigmented inks. Pigmented inks are particulate in their design. A pigmented particle has less surface area exposed to electromagnetic radiation than does a dye molecule, making it less prone to fading in sunlight. Lamination will increase the longevity of a pigmented inkjet print in an outdoor environment. Depending upon the equipment and ink manufacturer, pigmented inks are either oil, solvent or water-based.
The next step up in the technology food chain (ink wise) is printers that use a pigmented solvent-based ink technology. Solvent-based inkjet printers offer higher durability than aqueous based inkjet products. They are particularly suited to print onto vinyl for outdoor applications ranging from banners to vehicle graphics applications. A solvent is a liquid that has the ability to dissolve, suspend, or extract other materials without causing a chemical change to the material or solvent. Solvent-based inkjet printers come in two types currently. One contains inks that are more aggressive solvents and tend to have a wider range of substrate compatibility. The other type uses Eco-solvent ink, which contains less aggressive solvents, but requires a compatible media. Along with solvent ink’s high durability, it is important to consider that the use of solvents can lead to significant air emissions, triggering the need to comply with air quality regulations. These devices come in roll-to-roll or flatbed versions too.
Inkjet printers using certain types of solvent-based inks can print on uncoated vinyl and other substrates. Because the solvent bites directly into the surface of the substrate, a coating is generally not necessary in order for ink to adhere to media.
On average, solvent-based inks are designed to last 2 to 5 years in outdoor conditions without additional protection from over-laminates or coatings. However, it’s dependent upon where and how the digital prints are being displayed. Sun exposure, humidity and other factors can significantly affect longevity.
Currently at the top of the evolutionary ladder for inkjet technology is the UV (ultra-violet) curable inkjet printer. UV flatbed printers excel at printing onto rigid substrates, whether they are comprised of wood, plastic, glass or metal. This device uses inks that are generally composed of synthetic resin, into which colored pigments are mixed. Curing is a chemical reaction that includes polymerization (formation of molecular chains), and subsequent fusion with the substrate. This ink, in conjunction with a flatbed printer that can accept thick materials is positioned for new or existing markets. The ink is very resistant to UV fading and has good long-term outdoor longevity.
For the purposes of this article, let’s paint with a broad brush, widening our common perception of signage as a small, rigid print stuck on a wall or attached to a stick. The markets and applications of digitally printed signage are much too broad for such limited thinking. In fact, signage is often better defined by the products created and the markets served. Here are some of the most common:
On Sale. Meeting in Room 214. Small signs say all kinds of things, and digital imagers produce many of them. The sizes vary, as do the substrates, inks used, and methods of presentation. Digital imaging helps your client get its message across.
Whether they’re hung across the façade of a fast-food restaurant, or strung between two trees in front of a country church, banners are everywhere. Today’s banners are most commonly printed on vinyl and are printed using solvent-based ink systems.
The term “outdoor signage” is as broad as the outdoors themselves. Whether the signage is printed on flexible fabric or vinyl, or on rigid substrates, one similarity exists in all of them – the ability to face the harsh elements of the outdoors. Therefore solvent or UV inks are preferred.
Once printed in multiple sheets or even hand painted (imagine that!), most billboards today are printed onto a single piece of vinyl, and then installed using tension mounting. Obviously printing a billboard as a single piece requires a big printer. This is the realm of the grand format inkjet printer.