The Custom Screen Printing Process at Data Graphics

Creating Custom Screen Printing Stencils

Warning and Hazard Label Screen Printer

Custom screen printing has existed in some form since China’s Song Dynasty, but really came of age around 1910, when photo-reactive chemicals were used to bind emulsions to the silk screens. The compounds and chemicals we use at Data Graphics are much more environmentally-friendly, but the process is little changed since then. We stretch our own screens, cutting down on costs and never leaving us waiting for a third party provider. We even recycle when we can. While the term “silk screening” is still very common, in truth, screens have been made almost exclusively of polyester for the last few decades. The thread count of the mesh screens we use is wide ranging, from 80 to 390. Thread count is important to a screen printer. Let’s use a 200 thread count screen as an example. That means that each square inch of the screen has 200 vertical threads and 200 horizontal threads, essentially creating 40,000 tiny “windows” between the threads which allow the ink pass through. A lower thread count has fewer, larger “windows” per square inch, thus allowing more ink to pass through each. Having a wide range in thread counts allows our team to pick the appropriate thread count for the ink, material, and project at hand. In a dedicated part of the facility, free from debris and much foot traffic, we prepare and burn our screens. An emulsion, a gelatinous, glue-like substance, is applied evenly over the screen. A stencil is formed by blocking off parts of the screen in the negative image of the design to be printed; that is, the open spaces are where the ink will appear on the final screen print. This is “burned” onto the screen, using a ultra-violet light. The remaining emulsion is washed off the screen mesh. The screen has effectively now become a screen print stencil for one color of the print job. Each color must have its own screen “burned.” We have a small team who can stretch and burn screens, with decades of experience between them.

Color is Key

Next the color are mixed and tested on the materials. This would seem to be a relatively straightforward process, since we, like most screen printers, utilize the Index of Federal Standard Colors, as well as the Pantone and REL color charts. The same color ink, however, can look quite different on various materials and with different finishes. We can use any inks, from flat to high gloss. Color computers simply cannot compensate for material, finish, and lighting. Instead, Data Graphics relies on Tim and his team of color experts. Tim has more than three decades of experience in printing and has been the color guru for as long as anyone can remember. Tim is universally respected within the company because he is simply unrivaled at his job. No project gets run through the presses until Tim and his team are comfortable that the colors on the sample run are perfect.

Custom Screen Printing

As we mentioned earlier the actual process of custom screen printing is little changed over the years. Essentially ink is spread evenly across one end of the screen mesh. The mesh is lowered to just above the substrate (the material we are printing). Using even pressure, a squeegee draws the ink across the stencil, pushing the screen onto the substrate and forcing small amounts of ink through the mesh and onto the substrate. A screen printer can either underprint on the bottom of the label using clear or translucent materials, or overprint on the top of the label, using opaque materials. Different types of inks are used depending on the purpose and the material used. Some inks are dried using heated, blown air, and others are through UV exposure. Screen printers repeat this process for each color. Often times, a clear protectant coat is applied over the top, much like a protective clear coat on a vehicle. Data Graphics has four automated screen presses and three manual presses, two blown air dryers and two UV dryers. Each is capable of handling thousands of screen print jobs per day. This redundancy helps ensure that projects never get held up too long in production.

The Common Mishaps a Screen Printer Encounters

Top Custom Screen Printers

The most common error screen printers encounter are “pin holes,” tiny points where the ink did not cover the substrate. This can be caused by a defect in the screen, most commonly a tiny piece of debris that got into the screen mesh somewhere along the way. It is also possible the debris or grease found its way to the substrate. This is why cleanliness is so important to the screen print process. Our screen printers meticulously clean their machine and work places after every run. In fact, many of our vendors remark that ours is the cleanest print shop they have ever encountered. Another cause of “pin holes” is ink thickening. Some inks air dry quickly. Some print jobs are time consuming. Either way, as the consistency changes, the ink may not press through the “windows” of the mesh properly. An experienced screen printer can identify this and easily fix it. Our screen print crew is headed up by people with decades of experience and familiarity with every type of ink imaginable. This is something our team is adept at avoiding. To check for “pin holes” and other imperfections, our crew examine the labels using backlit exam tables and jewelers loops. Yes, they really are perfectionists. The other common problem screen printers encounter is a breakdown of automated presses. For many a screen printer, this would grind screen print operations to a halt, and delay projects. In response to these challenges, Data Graphics has Earle. He is the mechanical guru devoted to the routine maintenance and repair of all of our machines. Between our redundancy of machines and Earl, you will never be left waiting on a custom screen printing job.