Basics of Screen Printing
Table of Contents:
Basic Information Screen Fabrics Inks Printing Principle What to Print On Design Process Raster vs. Vector image Simple tips Printing to Film Making the Screen Taping film Exposing Washing Out Printing Process Taping Screen and Pinholes Lining up screens and shirts Flooding and printing Cleanup Process Screens Basic cleaning Reclaiming Squeegees, ink cups, and more.
Screen Printing Principle: Forcing ink through holes within a screen to create an image or design.
Different Types of Screens: Silk Polyester Nylon Metal Mesh Metalized Polyester
Types of Ink: Plastisol Water-based Alcohol-based
What to Print On: Substrate: The material you wish to print on. Some examples of substrates include garments and textiles such as tshirts, sweatshirts, or hats. You can also print on vinyl to create stickers or widow clings. You can print on practically everything, water bottles, bags, signs, flashlights, or posters. The only limit to what you can print on is the limit of your imagination.
Design Process Raster vs. Vector Image: Raster Image: An image made up of pixels Vector Image: An image constructed out of lines Benefits to using vector images: Because vector images are made up of lines that means that you can scale the image to any size and it can still be crystal clear. The only limitation to a vector image is the size of your canvas. If you tried to do the same to a raster image it would become blurry and the edges of the image would be undefined. This is why vector images are used in the screen printing process, images will always be clear and sharp no matter what you are printing on.
Designing in Illustrator: Adobe illustrator is one of the best programs to use while designing an image for screen printing. The program has a wide range of capabilities. Almost anyone at any level can learn to use illustrator to design a vector image. Basic Skills: Using the pen tool, click around your image at the corners or anywhere the edges changes dramatically. The pen tool creates anchor points that you can later convert. The less anchor points you use, the smoother your image will appear. After hitting all the points with the pen tool, click the convert tool in the sub panel under the pen tool. The convert tool lets you drag out two handles from your anchor point. When you click and move those handles around they will contort and bend. Using these handles on ever anchor point you can convert a simple straight line to match the edges of your design.
Separating Colors: When printing an image of two or more colors, you must use different screens to create that one image. Each screen must correspond with one color. For an example, take the dream catcher design. All parts dark blue must be on one screen, pink on another, and light blue on another screen. To make film of these you must turn all corresponding colors black, such as all the dark blue colors must be turned black, and the rest must be changed to white. After that you can print film of that color. Then change the color of the black to white and pick another color to print next. Do the same for each color within your design.
Printing to Film: Before you can go make a screen you have to print to film first. The reason why you must print to film compared to average paper is that when exposing your screen, light can still penetrate through the film, but not your image. Make sure the image you are printing to film is black. When you are ready to print, go to file print, select the plate maker printer, and tabloid size. Then go to the advanced setting and go to paper/quality to select manual feed and film. Once all of your setting are correct, press OK. Manual feed means you must put the film in manually. Take one sheet of film and feed it into the printer. After your film is printed you must run it through the dryer, sending the film through the dryer makes a more rich and darker black.
Screen Making Process After you have successfully sent your film through the dryer without setting anything on fire you can now begin to make screens!
Taping: First find a screen you would like to use, for almost all printing on garments you will use a 110 screen. Lay your screen on the table so that the pallet side, the side that lays on the pallet or shirt, is facing upwards. Then, lay your film image side downwards onto the screen. Try your best to center the your film on the screen, that will help you later when lining up your image. Exposing: After taping your film to your screen you can now put it in the exposer. Lay your screen pallet side down in the exposer, make sure each hose is on either side of your scree. Shut the top, latch it shut, and press start.
Cleaning out Screen: Take the tape off of your exposed screen and place it with the squeegee side facing outwards in the wash booth. Double check that both the water and the sprayer are on. Take the sprayer and wash out your screen top to bottom, once you can just make out your image, flip to the other side to finish washing out until you can see through the image. Be careful not to get too close to the screen or you make accidentally blow out part of your screen, although it is does happen you can always tape it up later.
Drying Screen: If you need your screen within the same day, after washing out your image dry it off with paper towel and place in the dryer beneath the exposer. From here screens should take about 5 minutes to dry total. If you donâ€&#x;t need to print within that same day, or are still waiting on your shirt to arrive, you can put it in a rack and let it dry over night.
Taping Screen and pinholes: After you have a nice dry screen you should then tape up the edges of your screen and any pinholes you find. Pinholes are the tiny holes in the emulsion that, if not covered, can potentially let ink through to your shirt. Taping the edges of the screen also protect the screen frame from getting covered in ink. Just a note, if your image is close to the top of the screen, you do not have to tape every single edge of the screen. Just tape up what you need.
Lining up colors and shirts: Once you have your screen on the press put the screen down and center it up in relation to the lines on the pallet. You may have to move the clamp head or the actual pallet in order to do so. If you are printing two or more colors the process does take a little more time. After you line up your first screen with the pallet, grab a test shirt and print that color on the shirt. After printing that first color, spin the pallet to your next screen. Put that screen down and move the screen around until it‟s lined up with that the printed color. The best way to make sure it‟s lined up is to check your registration marks and see if they line up with the ones printed. If they do then you are good to go.
When all of your colors are lined up with each other and with the pallet you are set to print on your final shirt. When you place your shirt on the pallet, if you need to straighten it up take the corners of the top or bottom and „steer‟ the shirt straight. If you try to move one section of your shirt by simply picking it up and moving it, there‟s a high chance that you might be putting your image on crooked, and you don‟t want to have to stand sideways in order for people to see what‟s on your shirt.
Flooding and printing: Once everything is all lined up you can now finally print! Place ink below your image, use only enough to print your image, don‟t take the whole container and plop it on there. When selecting your squeegee, first look to see if there is one with the same color of ink you are using, if there is one use it. If not, find a squeegee that is just wider than the widest part of your image. Before you print, make sure you tape over your registration marks! (Seriously, don‟t forget that.) The actual printing is quite simple, flood once, print twice. To flood the image, pull a good amount of ink over your whole image and stop after you clear the top of your image. From where you stopped your flood you will start your print there, to print you push the ink back over the entire image. You will print twice. Make sure you “print like you mean it.”
After printing your image, carefully take your shirt off the pallet and lay it flat on the dryer. Don‟t forget to also take your screens off and add them to the tower of screens to be cleaned. When your shirt has made its full trip through the dryer and of course after it has been critiqued and judged, you are now free to show off your wonderful printing skills and awesome new shirt!
Cleaning Process: Once you have finished printing your shirt there is still one more step left in the printing process, the clean up process.
Screens: Washing Screens: When washing screens you must first make sure you have everything you need to clean screens, paper to put screen on, gloves for both hands (it may take a bit of searching to find a right and left), cards, cloths, and the “apple juice”. Grab a screen a put it onto the paper so less ink gets onto the counter top. Take the cards and scrap off excess amounts of ink from the screen an put back in to the correct ink cup. Next, take the “apple juice” chemical and squirt onto the screen, with gloved hands rub the chemical over the entire screen. Take cloths an wipe down the screen to the cleanest it can possibly get. After washing your screen place it next to the dip tank and spray booth to be reclaimed.
Reclaiming Screens: Reclaiming screens is the process of removing the ink from the screen so it can later be recovered and used again. Take three screens together and place them all in the blue dip tank for 3-5 minutes, do not let the screens stay in longer. If in the dip tank for too long the frames will warp and it will ruin the screen itself too. After letting the screens sit in the dip tank, remove them and place them in the spray booth. Spray out the entire screen so there is no orange emulsion left on the screen. After that they need to be degreased. To degrease a screen they need to be scrubbed and sprayed with the degreaser. After degreasing the screens, they need to be sprayed out once more, after that they can be placed in the rack and wait to be coated with more emulsion and start the process all over again.
Squeegees, Ink Cups, and More: When cleaning squeegees, follow the similar process to washing screens. Scrap off ink and clean off with a cloth, using the “apple juice” chemical if necessary. When you are cleaning squeegees, to test to make sure they are fully cleaned, if you can tough the blade to your face without getting any ink on yourself, that‟s one clean squeegee. For ink cups and presses, all you have to do is tidy up and wipe off any ink that may have splattered on any of the equipment.
Remember: There is always something to clean!