A More Sustainable Screen Printing Industry

Screen printing has long been an industry with significant health and safety hazards to employees and the environment, due to the use of solvent-based inks releasing VOCs into the air and mercury vapor UV lights that produce ozone and require special hazardous waste disposal. Through the development and roll-out of more sustainable printing technologies, those hazards have been significantly reduced, for the benefit of employees, customers, general consumers, and the environment.

A History of Polluting Processes

The screen printing industry was, for a long time, anchored in technologies that were hazardous to the environment and to employees working in print shops. Until the late 1990s, all screen printing was done with inks using 50% solid ink and 50% solvent; the solvents evaporated into the air during the ink drying process. Those solvents are known pollutants, and larger companies in the industry had to get permits for the levels of pollution they were releasing. Beyond local environmental impacts, these solvents are also known to be hazardous to humans. Companies employed HVAC technology to clear away the chemicals from the air, but no air handling system is 100% effective in removing evaporated solvents, and so screen printing workers were consistently exposed to health hazards at work.

In the late 1990s, ultraviolet (UV) light technology was developed that enabled companies to replace solvent-based inks with fully solid inks that, instead of drying through the evaporation of solids, cure under the UV lights. This technology was initially developed with mercury vapor lights, which, although better for the environment and employees than the solvent-based inks, are not without their challenges.

Mercury vapor lights create ozone and heat as they produce UV light, and so air handling units are still necessary. These units move air past the lights to cool them, and carry the ozone and warmer air away from the workspace. The lights have a significant energy draw to operate. The mercury vapor lights also need to be replaced after about 1000 hours of operation, and require special disposal.

Developing an Alternative

In the 1990s and early 2000s, as UV curing technology was being developed, consumer demand for sustainable products rose, and customers within the screen printing industry demanded more sustainable printed products as a result. Large corporations, in particular, demanded more sustainable products from their printers. With the printing processes described above in place, printers were asked to print onto recycled or otherwise sustainable materials, but the hazards in the actual printing processes themselves remained.

As a result, printers used non-sustainable and polluting technologies to print on sustainable materials, for a mixed resulting product. Some printers addressed this concern by taking the harmful inks and curing processing and adding in vegetable oil, labeling what was still effectively a hazardous process “sustainable.”

Empire Screen Printing, an industry leader, noticed the increasing demand for sustainable processes among customers, and at the same time wanted to invest in processes that carried less risk for their employees. Empire's owner, Jim Brush came across an article where LED curing was being used in offset and digital printing. He raised the question, can LED lights be an effective curing method for screen printing? John Freismuth, Empire's President took action and decided to collaborate with light and ink manufacturers to develop a UV ink curing process that included all the benefits of mercury vapor UV curing, but replaced the mercury vapor lights with LED lights that would eliminate the hazards and hassles associated with the earlier technology. In 2008, that question became a reality and Empire Screen Printing installed its first LED-UV screen printing line.

By replacing mercury vapor UV lights with LED ones, the screen printing process requires less energy, eliminates the need for air handling, and removes the difficulties around light disposal. As a result, LED-UV ink curing has become the leading edge in sustainable screen printing technology. Whereas mercury vapor lights could cost up to $35,000 in energy usage each year. For a large company like Empire, the reduced energy draw of LED lights reduces that cost to around $650 per year. With no ozone emissions and minimal heat generated, the lights can operate with only ambient air being recycled through the room without any hazards to employee health and safety.

In addition to benefits to the environment and to employees, LED-UV ink curing also brings process benefits to screen printing companies. Mercury vapor lights take time to heat up and cool down, so during the production day, mercury lights are always on. LED lights can switch instantly on and off. During the 9 second print cycle, the lights are on for 1 -1.5 seconds, giving the same level of curing consistency, while greatly reducing energy consumption. The reduced HVAC infrastructure means that more printing equipment can be fit into a smaller space, for more LEAN production methods. The curing process uses light, instead of heat, allowing for printing on thinner substrates without material distortion.

“Now that we’ve developed this LED curing technology, we’ve learned that there is simply no downside to sustainable printing and production,” Freismuth said. “The end product is of the same or greater quality than other methods, but at a fraction of the cost and without risk to our employees.”

Even though sustainable products usually cost more, the efficient process Empire developed means the company can offer more environmentally-friendly products to customers without any additional cost.

Making the LED Curing Process Available to All

Since 2008, Empire’s production lines have shifted to 80% LED and 20% mercury vapor. The company completely eliminated solvent-based inks from production as of 2018. The goal is to reach 100% LED UV ink curing over time; although not all ink series are compatible with LED technology currently, Freismuth said that the company is working with suppliers to reach this goal. The benefits of reaching that goal will be shared across the screen printing industry. Along with Empire’s own shift towards LED-UV ink curing, Freismuth and his team have been working to change the industry as a whole.

“We’ve made our LED-UV technology publicly available to our competitors because we believe it doesn’t serve anyone, ourselves, our customers, or the public, for us to keep this sustainable technology proprietary,” Freismuth said. “We want this clean technology to be available for the common good, which is why we open our doors to the public during our Partners in Printing Expo.”

Even so, the industry as a whole has a lot of catching up to do to reach the levels of sustainable production in place at Empire. Compared to Empire’s 80% LED curing, less than 5% of the industry as a whole is LED-based printing. What’s more, many production lines still utilize hazardous, polluting solvent-based inks.

“We’re hopeful that sustainable LED-UV ink curing, and the related manufacturing process improvements we’re continuing to develop, will catch on across the entire screen printing industry,” Freismuth said. “Besides being highly desirable among our customers and general consumers, sustainable production is far safer for employees and the environment, and the return on investment based on energy and disposal cost savings is incredibly rapid.”