Let us continue to take awareness of the screen printing. Take the flatbed prints for example, screen printing is also suitable for the flatbed printing. Although the digital flatbed printer has been widely used, it also managed. To actually cure the ink, you need a heat source to reach 320 degrees for your ink. If you can reach 320 degrees in 1 second, it’s cured. If it’s 10 seconds, it’s cured. As long as it reaches 320 degrees, you are good. A flash unit is a unit that you place over your platen (the arm that you place the shirt on). This flash unit is meant to flash the ink just long enough where it is not cured and it is not wet. This will allow you to print colors on top of colors if needed, and you will need it! If you have a flash unit over a platen, it has to reach 320 degrees to cure the ink.
This heat may eventually warp your platens, it will also heat your platen up enough that when you put another shirt on it and print, it might semi cure the ink in your screens, causing a clogging and poor printing so allow cool down time on long runs. The reason for this is, you would print white on a shirt, flash it, and then when the shirt comes back around to you, and it needs a second print. This gives you a good vibrant white.
If you are printing a color on a dark shirt, you would also print a white under base, flash it, then print an exact image with a different screen over top of it with the color you need. To increase your output a conveyer dryer is needed to increase your production. When you finish printing a shirt, you pull it off of your platen and place it on the conveyer dryer. Basically, it’s a dryer that has a belt on it that goes through a tunnel of heat. When it comes out the other side, it is cured. Again, use a heat gun when the shirt is about to come out, you point the laser beam at the ink and it will give you a temperature reading. Remember, 320 is the magic number!
There are so many manufacturers and types of inks, it’s good to find one and stick with them. Consistency is the key to success
You will also need squeegees. A squeegee is basically a handle with a rubber blade on the end. This blade is what you use to push or pull the ink through the screen and onto the shirt. Your scoop coater cannot reach all areas of the screen, so you want to tape out the areas that did not have emulsion, there are special tapes made to do this.
If you have a one color design, placing the screen on your press is quite simple. If you have more than one color, this is where the registration marks are needed. After placing your first screen on the press, you would do a test print. Place some ink on the screen and rest a squeegee on the frame close to the head. Pull the ink across the screen and onto the shirt then flash it. Next, take your second screen and place on the next head.
Align the registration marks on the screen to the marks on the print you made. Once in place, you can lock them in and adjust the joystick or micro registrations if necessary. Once locked in, do a test print. If everything is registered, you can tape up the registration marks on your screen and you are ready to print.
You will be working upside down when you print t-shirts. The collar will be closest to you. After placing the shirt on the platen, pull your screen down, look between the shirt and the platen, you should have a gap. This is called your off-contact. You need about 1/8” between the screen and the platen. This will give you just enough room to make a print and allow for the screen to snap away from the shirt which gives you a clean print. Some people will push their squeegee and others will pull, whatever is comfortable to you is best for you.
Most printers pull the squeegee, which means that when you pull down the screen, grasp the squeegee and pull the ink towards you. You want to have the squeegee at an angle, if you go too much of an angle, you will get a heavy print The good thing is, if the first print does not work out for you, you can print it again, right over top of it. The registration of the machine will be the same so even if you rotated the press and came back to it, it would still print good. Rule of thumb; Angle and slow speed for light inks, less angle and a faster print for dark inks, especially printing on an under base.