Proven advice for industrial applications and other situations where delivering less-than-flawless prints isn’t an option.
It’s true for just about every printing operation: Whatever they are printing today is much harder and more demanding than what they did five years ago. And what they printed back then was more challenging than five years earlier, and so on – all the while expecting superior results from printing equipment and processes that may have long passed their peak!
There are two predominate reasons why screen printing technology has handled this challenge relatively well. First, these higher degrees of difficulty and more stringent demands have slowly evolved over the course of time, not overnight. Parents, for example, do not notice their children growing each day, but they sure do. The changes only become apparent when looking back over the years.
The second factor in the apparently smooth transition toward more dynamic work with more controllable results is that screen making products have also advanced, in some cases significantly. This fact nicely dovetails into the theme of this article, because, like it or not, manufacturers have done their share – but have we, as printers, done ours by taking full advantage of these substantial developments? Are we taking these more technically advanced consumables and applying them in the manner prescribed? Or do we simply turn a blind eye to innovative materials, training, and astute instructions, thinking we can cruise along using techniques from the past because they still seem to work?
Often, the reality is closer to the latter, and it’s the barrier that prevents many printing operations from advancing their processing abilities. Ever wonder why screens that come from trade screen makers or other suppliers look absolutely magnificent? The truth is they really don’t — they were just painstakingly made following the instructions. Anyone can make “magnificent” looking screens, but only if they meticulously follow processing directives without cutting corners.
The problem I find myself wrestling with is that it doesn’t have to be this way, especially when an abundance of resources are available. Don’t get me wrong: Troubleshooting issues with high-performance printing applications keeps a nice roof over my head. My point is that many superb technical articles have been written on screen making, perhaps more than any subject, so what happens to them? I believe the truth of the matter is either apathy or WHADITW (we have always done it this way), or a bit of both. It’s wishful thinking for any printing operation to expect to profitably handle more challenging work without first preparing. Screen making goes hand in hand with the degree of print performance required – it’s impossible to deliver more than what was given!
From Ordinary to Extraordinary Results
Almost every challenging application requires some sort of critical result from the printing process. Usually, either the deposition uniformity is crucial or producing a sharp, crisp-looking image is imperative – or both. Whereas high-end graphic printing is primarily concerned with the two-dimensional aspect of a print from an aesthetic viewpoint, many functional applications necessitate the three-dimensional accuracy of the ink deposit in order for the product itself to work.
This is why elevating the printing process has never been as important as it is today. New product innovation has accelerated at an alarming pace and so have performance requirements. This imposes more stringent controls than ever before on what is essentially an artistic process. If suitable improvements are not made to enhance the quality level, then gaining this lucrative work will be tough.
These five secrets for producing screens will elevate your results from ordinary to extraordinary, and then some. They are presented, except for the last item, in the sequence in which screens are made.
Secret #1: Frame Size Matters
A department supervisor concluded a hands-on training session in screen making with a smile and, in a raised voice, told her team: “It’s not the frame size – it’s the image-to-frame ratio, stupid!” Abruptly put, perhaps, but that’s what it comes down to: Is there sufficient mesh clearance between the image and frame to lessen troublesome image distortion and related issues? As squeegee pressure is applied, the mesh stretches outward due to off-contact distance and, if used, peel-off. More importantly, the closer the image and/or squeegee is to the frame’s inside edge, the worse the distortion will be due to the mesh’s severe angle of deflection. (See Figure 1.)
Other than guessing, the three most commonly used methods to establish the maximum image size for a given frame are by measurement, ratio, or proportion. The first approach uses a minimum dimension from the frame’s inside edge for placement of the image (such as 6 x 8 inches) regardless of the frame’s size; the second involves an image-to-frame ratio (IFR) that meets each job’s specific requirements; while the proportional method requires the frames to be physically twice the squeegee stroke length and triple its width, for example. The proportional method places a greater limitation on image size than going by the IFR, which I personally prefer for more stringent applications. Whatever system is used, the frame must be large enough to adequately support the whole image within the tolerance required by the application. Critical jobs are more likely to be doomed from the start – or at least made exceedingly more difficult – if frames are undersized.
The advantage of the IFR method is that it doesn’t assume all jobs are the same. Figure 2 shows different types of printing specialties loosely grouped together and at different general image sizes, providing a reasonable IFR that could be adopted as a benchmark or starting point. Each job may have different challenges to overcome. For example, the customer’s specs for one particular job required an IFR of 30 percent, while a similar job, size, and ink for another customer demanded the IFR be reduced to 22 percent – simply because the second job had tighter electrical specs.
One could reasonably argue that the latter job was over-engineered based on the client’s specs, a subject we’ll revisit. But the example demonstrates why frame size does not always influence the acceptable maximum image size, as additional tolerances (print or otherwise) must be met according to the job specifications.