June 8, 2019
By Bob Honn
According to a report by InfoTrends, more than 50 per cent of large-format commercial print providers are unable to produce the applications requested by their customers, either due to a lack of time or the inability to print the application using their existing equipment.
As a result, they have to turn away business or outsource customer requests to a third party. These options represent massive margin hits to a print provider, as well as run the risk of damaging customer relationships—or losing business to competitors.
As commercial print providers look to expand their customer base and establish a competitive differentiation, it is imperative to have the right large-format printing solutions and technologies in place to meet customers’ requirements quickly and economically.
As the world of large-format printing continues to evolve and experience rapid growth and change as new technologies come to market, demands for these solutions are also increasing.
Understanding which of these new technologies are most appropriate for one’s current and future business needs can be a time-consuming and complex process. Therefore, understanding the differences of each technology is critical. This article will take a closer look at the pros and cons of different large-format printing technologies, including aqueous, solvent, and latex inkjets, ultraviolet (UV), and water-fast, proprietary direct-dry prints.
Aqueous refers to the liquid that carries the colourant—in this case, water. Water-based inks come in two varieties—dye and pigment. Dye inks are suitable for dry environments, short-term use in UV light, or indoor lighting only. Therefore, they are primarily used for short-run promotional work and portable indoor displays such as pop-up stands where image quality and striking colour are critical. With certain coated media, a degree of water resistance can be realized with dye-based inks.
Pigment inks are best thought of as chalk dust suspended in water. The colourant particles are bigger than those of dye inks, but not by a great deal. They remain small enough to give a small dot size, and a good high-resolution image. However, when light hits this rough surface, it is scattered, which leads to a slightly muted colour response. So why use pigment inks over dye? Once dry, if water is poured over pigment inks, the particles will largely remain behind on the surface—meaning the print is considered short term water-resistant. However, neither dye- nor pigment-based aqueous inks can be considered waterproof due to their inherent nature of being water-based.
Aqueous printers use a water-based ink that is environmentally friendly (i.e. they do not emit harmful fumes). These printers plug into a regular electrical outlet and require no special ventilation. Aqueous printing still produces the finest resolution with superb quality due to smaller droplet size. Pigment inks boast the largest colour gamut available in all of the printing technologies. Additionally, these printers are relatively inexpensive to purchase.
Aqueous printers require a special coating on the media for ink to adhere properly for graphics applications, and paper and ink can be slightly more expensive.
There are also long dry times associated with this technology, especially on higher coverage prints, making stacking and finishing cumbersome. It can also lead to users damaging the prints if the inks are not completely dry.
Solvent inks are generally pigment inks. They contain pigments rather than dyes, but unlike the aqueous version where the carrier is water, in solvent inks, the carrier is volatile organic compounds (VOCs).
The main advantage of solvent inks is they are comparatively inexpensive and enable printing on flexible, uncoated vinyl substrates. Unlike aqueous inks, prints made using solvent-based inks are generally waterproof and UV safe (for outdoor use) without special over-coatings. Solvent can offer excellent vibrant colours, albeit often not as strong as aqueous dye or pigment inks.
A key benefit is the durability of the print, which offers excellent outdoor life. Hard solvent ink offers the greatest durability without specialized over-coatings, but requires appropriate ventilation of the printing area to avoid exposure to hazardous fumes. Mild or eco-solvent inks, while still not as safe as aqueous inks, are intended for use in enclosed spaces without specialized ventilation of the printing area. Mild solvent inks have rapidly gained popularity in recent years as their colour quality and durability has increased while ink cost has dropped significantly.
Solvent printers produce a very durable, scratch-resistant product that is typically used for outdoor applications. They print on uncoated materials and essentially “etch” the surface of the material to bond securely to the substrate.
As a result of VOCs and fumes, solvent machines require excellent ventilation. Complete drying can be an issue for media that needs to be finished, specifically lamination.
Solvent inks also need to allow for outgassing. This is the time it takes for the carrier elements in the ink to leave the surface of the material. The recommended time for this process before lamination is anywhere from several hours to a day; this leads to a very labour-intensive process for each print when considering finishing times needed for laminating, storing, packing, and shipping.
UV gel technology combines a radically new UV-curable ink that instantly gels on contact with the media, an advanced “self-aware” piezoelectric print head technology, an LED-based UV system that cures without adding any damaging heat to the media, and continuous, on-the-fly, print head nozzle monitoring and performance compensation.
UV gel ink does not contain water, which also significantly helps to reduce media swelling, improving dimensional consistency. This gives excellent results for applications requiring multiple tiled panels, such as wallcoverings. Prints are durable, lightfast, and abrasion-resistant, which makes them suitable for demanding outdoor applications.
This ink has been developed to be nearly odourless and ultralow in VOCs, so prints are ideal for sensitive indoor environments. The flat profile of the UV-gel dot produces smooth prints that are easy to laminate straight off the printer for heavy-duty applications. Inherently, these prints are highly resistant to environmental stresses, which minimizes the need to laminate for all but the most demanding applications.
This ink instantly gels on contact with media, resulting in precise dot gain and positional control, perfectly repeatable images, and instantly cured, durable prints. The state-of-the-art, low-temperature light-emitting diode (LED)-UV curing system moves independently from the printing carriage to enable uniform, post-print UV curing, which contributes to print speed and quality. Confident unattended printing and roll change, and automated quality assurance help to reduce print waste and significantly contribute to overall productivity.
UV gel systems bridge the gap between 1625-mm (64-in.) eco-solvent and latex systems with 3.04-m (10-ft) UV and latex production machines. As such, they are ideal for helping to increase the productivity and cost of operation for users of the former and flexibility for shorter runs and media versatility of the latter. That said, these printers may not be ideal for providers who have limited large-format print volume.
Latex and resin-based inks have increased in popularity over the last several years. These ink systems use water as the main ingredient, but the carrier for the pigments is either latex or resin-based.
Printers using these types of inks also need built-in heaters so the media becomes receptive to the ink for adhesion and enables the ink to dry properly. Latex is said to offer equal or improved performance compared to solvent ink for printing on vinyl (polyvinyl chloride [PVC]), as well as printing onto paper, fabrics, polyester, and polyethylene—substrates which solvent technology is known to struggle with.
The latex ink, which is water-based with a polymer that is bonded to the substrate by heat, does not need air purification or solvent extraction. It is also odourless, making it suitable for a range of indoor applications where solvent machines are not. The output is promised to have an unlaminated exterior life of three years. Another advantage claimed over solvent is the print is dry and can be finished and mounted straight from the printer without requiring the outgassing period. However, as the printer uses a built-in, heat-based curing and drying system to ensure the output exits the equipment completely dry, it increases the print time.
Since the inks are water-based, there is no need for extra ventilation to remove any harmful substances emanating from the printer. The water-based formulations of latex inks reduce the impact of printing on the environment. They produce durable printing for outdoor and indoor applications. Additionally, prints also look excellent for signage applications.
Latex printers require preprint and post print heaters to cure the media, resulting in higher energy consumption compared to other inkjet technologies. Some substrates may buckle under the higher temperatures needed to cure the ink onto the substrate.
Slow speed may also become a bottleneck for certain applications as adequate heating/curing must occur in-line, variable with media type and coverage.
UV-curable printers, unlike aqueous or solvent printers, use ink where the carrier is not evaporated and the ink does not dry—it is cured using ultraviolet light after printing.
UV-curable inks “dry” as soon as they are cured, can be applied to a wide range of uncoated substrates, and produce a very robust image. That said, these materials are considered expensive and require costly curing modules in the printer. Though improvements are being made in the technology, UV-curable inks (because of their capacity and heaviness) are somewhat susceptible to cracking if applied to a flexible substrate. As such, they are often used in large “flatbed” printers, which print directly to rigid substrates such as plastic, wood, or aluminum where flexibility is not a concern. However, these inks are being used more often in “hybrid” printers to print onto vinyl and other flexible media traditionally associated with solvent printing.
The colourants in UV-cured inks can be dye or pigment-based. The latter is more common; however, because of its greater light fastness and durability. Pigments used in outdoor advertising and display applications have similar requirements to those used in automotive paints.
UV printing does not require coated media, resulting in cost savings on many materials. UV-curable ink dries (cures) almost immediately and is very durable outdoors. These inks can print onto just about any substrate, including foam board, wood, cardboard, glass, vinyl, and many others.
UV inks are less conformable to media that stretches such as vinyl for vehicle wraps. As it does not dry flat on the media, a perfectly dried printed image will have a matte look. While UV printers have made great strides in the past several years, they are still not comparable to solvent, or, in some cases, latex printers in this respect. High quality UV printers can also be more expensive than roll-to-roll systems.
Some proprietary technologies bridge several advantages of both traditional inkjet and LED printing and are ideal for a wide range of applications including graphics, computer-aided design (CAD) plots and GIS documents.
This proprietary process converts (melts) solid toner into a gel via the printer’s imaging devices. This toner gel is then jetted and crystallized onto the media roll, producing crisp, water fast, high-quality images with extremely accurate dot placement. This allows users to print high-quality images on inexpensive and recycled bond as well as presentation media such as semi-gloss, polypropylene, fabrics, wallpaper, and even vinyl.
Typically, because the fibres in this type of media are very coarse, other inks used in conventional inkjet technologies land on coarse fibres and either feather or run. When the toner gel is jetted, it lands on the media, but will not run because it is crystalized. This is referred to as “solid in, solid out printing.” Also, since the gel is crystalized as soon as it hits the media, it dries instantly, which means the print comes out dry, cut, and ready to be used, without post-printing preparation time for complex finishing needs. This toner is not UV-cured; therefore, its lifetime durability outdoors is limited. As a result, the toner will fade over time when in direct sunlight, which is why the technology is suggested for short-term indoor and outdoor signage.
This proprietary technology produces highly accurate fine details and sharp lines with no toner feathering. The solid toner also produces a shine when placed onto the media, which boosts the image quality on plain papers, unlike inkjet technologies where the image would be viewed as dull or flat or even over saturate the media.
Prints can be handled immediately, which save the cost of long preparation and finishing requirements that are common when using solvent and latex technologies. Print engines using this technology also offer multiple rolls, which allow operators to print uninterrupted as well as have multiple types and sizes of media loaded and ready to use, which further increases productivity.
Colour prints can be produced at the speed of a black and white printer, giving the user the ability to print a wide range of applications—from graphics to CAD work—on one print engine quickly and cost effectively. Due to the water fastness of the toner, the prints can be placed outdoors, specifically on media such as vinyl and high-density polyethylene. The technology is also clean, so there is no odour, toner dust, or ozone.
As the print engine needs to be heated to 130 C (266 F), it may take a few minutes to warm up when it is initially started. The solid toner is also sensitive to UV light and may fade in the sunlight over time. The suggested outdoor durability length due to fading is estimated at approximately 30 days, dependent on the specific environment.
Even with an understanding of the trade-offs of each of these large-format printing technologies, the question may still remain, “Which one is the best investment for my business?” In many instances, there is no single ‘perfect fit.’ In reality, commercial print providers need a combination of the above-listed technologies to stay competitive and print the widest variety of customer requested applications in-house, with the ability to meet deadlines, while also saving costs and being profitable.
A large-format hardware vendor can help companies determine which technologies make sense for its current and future business needs. For print service providers who are ready to update or expand their large-format solutions footprint, it is critical to select a vendor that offers the widest selection of technologies and has industry-specific knowledge to help guide them through the selection process to ensure they not only remain competitive, but also grow their customer base and profits.
As senior director, marketing services, Bob Honn is responsible for all marketing support programs within the large-format solutions division of Canon Solutions America. With more than 30 years of comprehensive experience in the printing and digital imaging industry, he provides the company with customer-centric solutions and programs. In his current role, Honn is responsible for all outbound and inbound marketing activities, managing both the technical document and display graphics reseller programs, as well as special projects.
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