Screen making is vital to good apparel decorating, since the quality of a screen-print design will be very influenced by, if not dictated by the quality of the screen.FULL STORY
Screen Printing: Process + Techniques
Excerpt: Screen-Printing Odds and EndsIn the third of a series of three excerpts from his book, The Screen Printers Handbook and Survival Guide, veteran decorator Charlie Taublieb discusses the specifics of screens, frames and squeegees
The best screen-printing press in the world is only as good as the screens and squeegees you supply it with. Photo courtesy of Impressions Expo
As is the case with any craft, when it comes to screen-printing the devil is in the details. The best art, the best press in the world will inevitably come up short if you don’t take care of the little things as well.
When I got into the screen-printing industry, there were very few choices about what kind of screen frame to use, especially on the textile side of the industry. The choices you had were to purchase ready-made wooden frames or make your own, which is what we did. Screen tension was not considered very much of an issue, so these sufficed.
There were metal frames available, but they were quite costly compared to wooden ones, plus, you needed a stretcher. With the wooden screens, you only needed a staple gun and strong hands, though a stretcher helped. There were other ways of stretching a wooden screen as well. The cord-and-groove method was one that only required a simple tool, but was a bit uncontrollable as to the tension you would achieve and would split if you hit the cord in too far.
The fact that there are still companies using wooden screens today amazes me. It’s like driving a horse and buggy instead of a car. I don’t have anything negative to say about horses. But they don’t provide the fastest or most comfortable form of transportation. Going cross-country could take a while, though you don’t have to concern yourself about the cost of gas!
Wooden screens are immersed in water after being exposed in order to develop the image. Wood in water with some tension on it will warp, making it difficult to hold registration among other things. Definitely not the best option in today’s world.
Rigid metal screens are a better choice but have their downside as well. The cost of aluminum frames has come down considerably in the last few years, and it is easier for printers to buy them. However, there are a few issues that I have with them. For example, you have no idea what the tension is, since you’re not the one stretching them, and even if you have a tension meter, you still can’t adjust the tension. In order to have predictable results screen printing you have to be able to control the variables, with tension being one of the important ones.
The reasons screen printers purchase rigid metal screens are their cost and ease of use. This seems valid, until you have issues and have a difficult time resolving them. Ink not clearing the screen, registration issues, print clarity and the ability to repeat an image based on previous jobs are some of the issues. That being said, these are the most widely used screens in the industry.
Retensionable screens are definitely the ones with the most control. However, while they allow for the control of tension, they are also high maintenance. The most popular ones are the Newman Roller Frames made by Stretch Devices, although there are others that use a different method for stretching. These require stretching the mesh to a certain tension, letting the mesh relax, then retensioning several more times before finally being used. After being used, they require yet more retensioning until the mesh is “work hardened,” meaning the tension before printing and the tension once done are the same. Unfortunately, this could take 10 to 15 retensionings or more, depending on the mesh count. Therein lies the problem. Most screen printers do not want to go through the process of retensioning the mesh. Those printers using these screens definitely have the most control of their printing.
There is one more type of frame that I call a semi-retensionable screen. These are made by Shur-Loc and are called EZ Frames. There are two types: one that usually does not get retensioned, although it is possible, and another one that usually does get retensioned, but only once or twice. EZ Frames require using a mesh panel that is laser cut and has locking strips attached. The tension is dictated when the panels are cut, and a special stretcher is required. Many companies that were using Newman Roller Frames have switched over to the EZ Frame due to its ease of stretching and high tension.
When it comes to choosing a screen frame, go with the type that will suit you best.
I conduct a lot of textile screen-printing workshops and seminars, and I am always amazed at the responses I get to a few questions I ask about squeegees.
I would like to state that I prefer using squeegees that are sharp and straight no matter which garment color will be printed or the detail that will need to be held.
The first question I ask is, “Do you know which squeegee hardness or durometer to use based on the type of work you are going to print, and the ink type you will be using?” The next question is, “How many of you own automatics?” Based on the reply, the next question is, “Of those of you that own automatics, how many of you don’t own a squeegee sharpener?” It amazes me how many print shops don’t have them, and when I ask why not, the answer often is, “I’ll buy new squeegees once these wear out.” I cannot believe how many manual and automatic shops only have one set of squeegees per press. These are some of the least expensive production tools to own and choosing the right hardness of blade has a massive impact on the quality, detail and vibrancy of the finished print, especially when printing on dark garments.
So, let’s take a decent production shop and let’s say they average 1,500 prints per day. At the end of a month, they have printed about 30,000-35,000 units. Do you think the edge of the blade may have gotten worn down? Will you really purchase a new set of blades each month? Not very practical, is it? About 40 percent of the inks sold are white. That being the case, it would probably be a good idea to have one or two squeegees that are dedicated to being used only on white ink.
Here’s a brief rundown on the squeegee hardness I like to use for printing textiles based on garment color and detail to be held.
1. 75/90/75 Triple Durometer: Four-color processes with an automatic and for very fine detail on light colored garments.
2. 75 Durometer: Four-color processes with a manual and for very fine detail on light colored garments.
3. 65/90/65 Triple Durometer: Used on an automatic for printing the underlay and on top of an underlay; light colored garments where a stronger color is desired. Used for water base and many special-effect inks, such as high density. This is my favorite for most prints on an automatic.
4. 65 Durometer: Used on a manual for printing the underlay and on top of an underlay. Light-colored garments where a stronger color is desired. Used for water base and many special effect inks, such as high-density. This is my favorite for most prints on a manual.
5. 62/90/62 Triple Durometer: Very similar to the 65 Durometer squeegee, but a little softer than the 65/90/65 and a little harder than the 55/90/55. Use for getting a good ink deposit on top of an underlay. Use on an automatic or manual press.
6. 55/90/55 Triple Durometer: Great for underlays, water base, gels and any ink where a large deposit of ink is needed. Use this on manuals and automatics.
Beyond that, there are a number of “special squeegees” to be aware of.
Double Squeegee—This squeegee has two blades in the holder and is made for automatic presses. The front blade is a 55/90/55 and does the finish of the print. The back blade is a 62/90/62 and starts laying down the ink. One print stroke with this blade is equal to or possibly better than two strokes of a standard blade. Although this blade has to be set to 15 degrees to work properly and prints on the slow side, the production with this blade is 30 percent more than a double stroke.
Roller Squeegee—This squeegee is used in combination with a screen that has a hard Teflon sheet mounted to the bottom of it. This screen follows right after the flash. As the flash starts to cool down, the pallet moves, and the hot ink is sent under this screen. The Roller Squeegee then comes down on the screen and rolls over it, which flattens and smooths the print. This makes the print look brighter. The remaining colors, especially those with detail, will now be printing on a smooth substrate. There are also Roller Squeegees made for manual printing.
Choose the squeegee that will give you the best results. Not just the one that is clean!
Veteran decorator and screen-printing guru Charlie Taublieb is both the principal of Taublieb Consulting and a regular Impressions Expo conference program presenter. His new book, The Screen Printers Handbook & Survival Guide, is available either digitally or in the form of a spiral-bound book at taubliebconsulting.com. To see Part 1 of Impressions’ three-part series of excerpts, click here. To see Part 2 of Impressions’ three-part series of excerpts, click here.
Updated Feb. 2, 2023
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