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 technologies such as LED-based UV curing technology, those hazards have been significantly reduced, to 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 1,000 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 sustainably printed products as a result.

Large corporations in particular demanded more sustainable products from their printers. With the printing processes like the one 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.”

We 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. Our owner, Jim Brush, came across an article where LED curing was being used in offset and digital printing and wondered if LED lights could be an effective curing method for screen printing.

I, along with our team, 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, Empire Screen Printing installed its first UV-LED screen-printing line. This is just one technology that’s been developed in the industry to further sustainability efforts — there are others.

Safer for Employees and Environment

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, UV-LED ink curing has become a big player in sustainable screen-printing technology, whereas mercury vapor lights could cost up to $35,000 in energy usage each year. For a large apparel decorating company, the lower energy draw of LED lights reduces that cost to around $650 per year (depending on a variety of factors). 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 employees, UV-LED 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 nine-second print cycle, the lights are on for 1 – 1 1/2 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 leaner production methods. The curing process uses light, instead of heat, allowing for printing on thinner substrates without material distortion.

Now that this LED curing technology has been developed, we feel that there is simply no downside to sustainable printing and production. 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.

Making the UV-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% UV-LED ink curing over time.

Although not all ink series are compatible with LED technology currently, we are working with suppliers to reach this goal. The benefits of reaching that goal will be shared across the screen-printing industry.

We’ve made our UV-LED technology publicly available. We want this clean technology to be available for the common good.

We’re hopeful that sustainable UV-LED ink curing, and the related manufacturing process improvements that are continuing to develop, will catch on across the entire screen-printing industry. 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.

Advancements in screen-printing technology that replaces solvent-based inks with fully solid UV inks and mercury vapor lights with LED bulbs are at the forefront of sustainable production.