Screen prep is often a thankless job. This month, Roberts addresses the importance of the screenmaking department and sets the stage for a series of columns in which he'll discuss ways to improve quality and efficiency in this critical area.
OK, let’s have a few minutes of respectful reflection for our comrades who have gone before us—the brave souls we have buried in the dark, dank, and yellow-lit bone yard in the back of our shops—the area we often refer to as the screen-prep area. You know who I’m talking about. They are the people who you summon to the press to yell at when the emulsion breaks down. You curse them as you climb up under the screen to fix some missed touchup, and you want to strangle them when they expose your last screen of the day backwards.
You don’t like the way they tape your screens, and they never seem to get all the ink off the frame when they reclaim. You swear that the mesh counts they are giving you are wrong. Every once in a while you borrow a tension meter, put it on a screen, and let out a triumphant “Aha!” to prove to your boss that it’s not your fault that the job won’t print. “The screen isn’t tensioned correctly. The film is not placed correctly. The screen ripped because it’s not blocked out correctly. It had better be fixed by the time I get back from break.... What’s that? You can’t quit now! Who’s going to expose screens!?” Sounds familiar, doesn’t it?
I would like to state something for the record, and I’m willing to pound my fist onto the desk of anyone in this business who dares to disagree with me. I believe that there is no more skilled and difficult job in the print shop than screen preparation, and the people that do it deserve a lot more respect than I ever see them getting. I would hope that at least a few of them might see this article and gain some spiritual sustenance from it, but I doubt it. They don’t have time to spend relaxing between the pages of this learned magazine while they sip coffee in the break room. Most likely, they are outside grabbing a cigarette to calm their nerves and trying to figure out how they will solve the logistical problems that they consistently deal with every day.
Let’s take a quick look at what the screen-prep folks do. They badger the art department to get the film in time. Once they have the film, they use their loupes and thoroughly inspect the film, often returning it to the graphics professional to repair something that was overlooked, causing them to begin to get behind schedule. Then they select the screen that will be used for the job. Bear in mind that the screen had to be stretched, hardened off, and brought up to tension, and then roughed up, degreased, coated, dried, and thoroughly inspected again to ensure that it’s as close to perfect as they can possibly make it. Remember, a lot of this is happening in lighting conditions that would make the average person see double.
Next, they select the correct exposure, which they have previously calculated, taking into account the age of the exposure light source and the lack of accuracy that the UV counter on the exposure frame almost invariably has. They carefully clean the glass, knowing that the effort will greatly reduce dust pinholes, but it won’t eradicate them. Next, they lift the screen onto the glass, making sure that they don’t scratch it. They engage the vacuum frame and cross their fingers, hoping that the repairs they had to make to the rubber blanket will hold and the vacuum will draw down correctly. If it does, they have a few moments of peace while the exposure unit does its work.
This is usually the time when the screen-prep people are dragged out to the press to hear about their shoddy work and how it has caused the loss of valuable production time. They know exactly why these things happen, and often they know that there is little that they could have done to prevent the problems. They also have learned that it takes a lot more time out of their day to explain the reasons for the problems, so they apologize and go back to making screens. They wash out the screen thoroughly, vacuum off the excess water, and place the screen in a drying cabinet.
Typically, this is when the production manager arrives and asks where the screen is because it’s due to be on the press next and the job has to ship today. The question is always the same: Can’t you speed it up a little? The screenmaker knows very well that the most dangerous thing that he can do is to hurry up the process. The screen-prep person also knows that the best made screens are the ones that have sat all night in the drying cabinet before they were exposed. However, as usual, there is no time for that, so the screenprep folks have learned to live on a knife’s edge, always pushing the envelope and using their skill and judgment to get the job done on time with as few problems as possible.
Next, the screen prepper blocks out the screen and fills in pinholes. How hard is it to dab a little filler into a hole? You often ask this question when you summon your prep person out to the press to point out the holes he or she missed. Mean- while, they are thinking that they might not miss so many holes if they weren’t interrupted every few minutes. But once again, they know that it’s better, and often less stressful, to smile and apologize, and then get back to work.
With this attitude, the screen-prep people know that there is a possibility that they might even make it home at night to see their loved ones before they are all tucked in bed. Then it happens, as it always does, at the worst moment. You forget to check the squeegee pressure on the first stroke, and the screen rips. Now it’s time for the prep person to start grumbling at you, but it makes no difference because the meticulously planned screen-prep day, which was looking like it might actually work out, has just gone out the window and everything has to stop while your screen is remade. Meanwhile, the screens from your previous job have found their way to the reclaim area. They are the screens that you didn’t have time to clean last night before you left, so they are a little on the sticky side, and the ghost image has hardened up nicely in the mesh. Don’t worry, the nice man from the chemical company stopped by a few weeks ago and demonstrated a wonderful product that will removed the ghost image in a moment.
Let’s pause here for a second for another small dose of reality. Whatever the guys from the chemical company do when they visit and demo their products is a mystery because the remarkable results they achieve with their magical potion bottles full of cleaner, degreaser, and most importantly, dehazer, never reproduce those results when they are brought to bear on screen mesh. Of course, we realize this only after the 55-gal drums of magical potion have been ordered and dragged into position. Nevertheless, the poor screen-prep person in charge of reclaiming is expected to get rid of the haze in the same manner, and more often than not, has to resort to using a fiery-colored sludge that eats through his gloves and pops more screens than it saves. The screenprep person then places the screen in another drying chamber, where it will rip, apparently for no reason. And of course, the screen-prep person will be blamed.
This brings us back to the beginning of this never-ending roundabout of screens. Easy enough to fix, you might say. Now take all of the above scenarios and multiply by the number of screens your shop prints every day. Then multiply that by at least two so that you can always be at least a day ahead, and you will start to see how things work. All I’ve done here is skim the surface. Each one of these procedures takes a lot of time and experience to master, and most of these processes need to be thoroughly learned before they can be practiced. Think of all the possible permutations and the possibilities for things to go wrong, and you’ll soon realize that it takes a very special person to take on the responsibilities described in this column.
In my next few installments, I’ll help you figure out ways to make life a little more bearable in the screen room. But for now, why don’t you walk back to the screen department in your shop and tell your staff that you appreciate what they do. You might even initiate a group hug or something. Well, maybe you should skip the hug. Your staff probably can’t spare the time for that.
Gordon Roberts has a history in screen-printing production management that spans more than 25 years. He has held supervisory positions in shops that represent a broad spectrum of application areas and markets, including printed electronics, apparel, signage, and retail graphics. Roberts has presented training courses on the basics of screen-printing production and on shop management for the Screentech Institute and is presently a consultant for the screen industry. He can be reached at email@example.com.