Wednesday, October 08, 2008

Push versus Pull

After I posted the video on Printing White Ink on Black T-shirts which can be viewed in the post immediately before this post, I begin to get a number of emails about achieving results on printing white ink on black T-shirts successfully. There were hits from across the United States, Puerto Rico, Philippines, Romania, Canada, United Kingdom, Belgium, Thailand, Mexico and Germany.

All of the emails were quite positive. It seems that I had struck a chord with a great many people and they altered the way in which they were thinking to become more successful at printing white on black.

However, I received one email from a printer in the United States, who stated that he had tried printing with a push stroke and had great difficulty. I wanted to share our exchange of emails with my readers. I have changed the printer’s name in the article as I do not want to embarrass him. I will call him “Bob,” which is not his real name.

Bob: Yes, I got it. I must say I see your point, but I'm pretty sure I'll never, ever push a squeegee, it's just too uncomfortable for me. I've been printing since 1972.

Bill: Strange that you say that, Bob. Half of the printers around the world are pushers and find it quite easy. And more are changing every day. Those who I train at the School of Screenprinting or at one of the many trade show seminars, always say it is much easier and more comfortable than pulling.

You see, when you pull a squeegee, you use the smallest muscles in your body, the fingers to hold the squeegee. They grow tired quite rapidly and by day's end they are exhausted. When you push, you place the squeegee against the palm of your hand and use the large upper shoulder muscles to push the squeegee. The larger muscles don't grow as tired and thus you are still in good shape at the end of the day.

Bob: Well we did give it a shot, but as I said, we all found it too uncomfortable. For me in particular, it really aggravated my thumbs. We had a guy stop in once, and mentioned that where he was from, Tennessee, if I remember correctly, it was far more common to push than pull. In fact, they had wooden handles attached to their squeegees, which we found even more awkward than without the handle. As you said, half of the printers around the world; I'm in the other half. Technique aside, laying the ink film on top of the shirt instead into it, or worse yet, through it, is indeed the desired result. Remember the time before we had flash units? Printing 4 colors on a black shirt before flashing really developed your touch, but that's the caveman days for guys our age. Stapled mesh too...

Bill: You lost me there, Bob. What did you mean when you stated that "they had wooden handles attached to their squeegees, which we found even more awkward than without the handle." Don't your squeegees have handles on them? I am very confused as to how you would use a squeegee without a handle.

Also, if your thumbs are aggravated by pushing a squeegee, you are not doing it properly. Your thumbs are not used when pushing a squeegee, other than resting at the rear of the squeegee. Neither are your fingers. The squeegee rests against the middle of your palm, with the thumbs on the rear and fingers on the top. No pressure is exerted on the thumbs or the fingers, but only on the center of the palm.

As you stated, things have changed over the years - no more stapled mesh, no more degrading the mesh, no more Rubylith, no more stat cameras, no more pulling a squeegee! Yes, my friend, things change and we must move forward in our thinking rather than being stagnant. We must grow our thinking so we can grow our businesses.

Bob: I definitely didn't describe the handle correctly. It was a handle for the handle. It was mounted in the middle of the squeegee handle, and rose vertically. Picture a paint brush with a squeegee where the bristles would be. An operator would grasp it with one hand, and push it toward the center of the press, or away from oneself, using the opposite angle of what it would be with pulling the squeegee. Also, yes, we were bending the blade in the opposite angle from that which you displayed in the video, with the thumbs bearing the brunt of the force. Anyway, we do keep changing. My darkroom has been a file room for films for many years now, and the films are now ink jet, after 6 years with the Xante Screenwriter. Next, changing to the new generation of plastisol inks. Onward and upward...

Bill: Now the truth comes out. It seems that you are using a squeegee handle that is circa 1945 or earlier. This squeegee was developed after the old “one man squeegee” press. These presses are still being sold for printing medium and large format work by hand.

Here are some photos taken from books from the mid-1940s that explain the process then in use.

The thought process was that since this concept worked on the “one-man squeegee” press that it would work on other manual work. It really didn’t work well. I remember when I was working for Graham Outdoor Advertising in the early sixties, we ceased using these types of squeegees when we found it was much easier to print using a standard squeegee.

Also, your printing technique of pushing isn’t really pushing. You wrote of bending the squeegee the other way. What you were in effect doing was to simply “pull” the squeegee to the rear of the screen – done by reversing the angle of the squeegee. This really doesn’t change the mechanics of ink transfer, only the ergonomics of holding the squeegee.

What we want to do is achieve a better result of ink transfer. Altering the ink deposit and detail. While it is true that there are many other variables to control in the ink transfer mechanism such as the screen tensions, off-contact distance, ink rheology, squeegee durometer and type, print speeds, substrate variations, and esthetic goals, we must begin with the simple process of having the squeegee attack the ink transfer at the point where the squeegee edge meets the stencil. And the angle of attack that I use in the video is an important and approved method of doing so.

Let me show you using another illustration. Below you can see the how the traditional pull stroke (right) simply spread the ink, while the push stroke (left) does a much better job of ink transfer down into the mesh openings and onto the garment surface. Keep in mind that the angle of the attack, the length of the squeegee blade, the flexibility of the squeegee blade and other factors greatly affect the ink transfer when pulling a squeegee.

Now, here is the rub. There are a great number of individuals using outdated information, tools, and techniques that have been replaced by more current technology. We see that in your choice of squeegee and reverse ergonomics. Many people get stuck in “that’s the way we have always done it, and we are not going to change”. This stagnation keeps one from growing as fully as they might. As my good friend, Don Newman, founder of Stretch Devices and the inventor of the Newman Roller Frame in 1981 has so often stated:

“Remember, new technology is rarely a quick fix. Improvements in print quality and speed usually comes at the price of hard work, testing, and an open mind to new possibilities. The presspersons that get better and faster each year are constantly testing, working harder, applying constant creativity, and are more persistent than their peers might think.”

I believe that if you learn to think with an open mind, that you too will learn to be more passionate, creative and indeed more understanding of the screenprinting process.

This is not a “What works for one does not work for all!” This process does work for anyone who cares to duplicate the effort to receive the same or better results. I have taught thousands of printers to use a better ink transfer mechanism through sharing my knowledge and understanding of the screenprinting process.

Bottom line it is never the work that counts, but the results that one is able to achieve.