I got the idea for this post while looking at the search terms that people used to get to vacord.com. If you’re a printer with a website for your services, see if you can get statistics for your domain if you don’t already. It’s great to have them, as it can help you tweak your Search Engine Optimization by seeing what people search for that makes them end up at your site. Screen printing is a printing technology which is widely used. So does the screen printer. You can choose the screen print if you like.
Anyway, I want to go over the processes of screen printing, step by step.
1. Prepare artwork. You need high quality artwork in a digital format. Read my post about the various file types adequate for screen printing. Art needs to be made into pure dark black, and if it is a multiple color design, every color needs to be split into its own layer, and then made ebon black. Label those layers so that you don’t get confused as to what is what.
2. Print a film. A film is like a high quality transparency. I use 8.5×14″ legal size and 13″x19″ oversize films that I get from PosJet out west and print them with an Epson 3000 large format printer. Make sure that your design on the film is as dark as possible. Hold it up to the light and make sure that it blocks the light extremely well. If you’re using a laser printer to make films, get some tone enhancer, which you can spray on a printed film and when it dries the design will be darker. When I used to do this, I used Casey’s Ultra Black, “Blacker blacks in a can.”
3. Burn the screen. Tape the film to the bottom of the screen, reversed, so that the design will be burned to create a stencil correctly. I use a little tape measure to make sure that the design is taped on level, and also if I’m doing multiple screens for a multi-color design, I make sure not only that they are level, but that they are in the same place. I even write down the distance so that they are all equal. Tape the film on, then expose the screen for a proper amount of time, then remove the film and go wash it out to create the stencil. After drying the screen, you may want to put it back in your exposure unit for 20 to 30% of the original time to harden it. This is what I do now, since I use Mirakami Aquasol HV emulsion which needs hardening when doing more than a few dozen prints at a time. There are also liquids you can spray onto a screen to harden it instead of doing a post-exposure.
4. Tape the screen. Different screen printers use different sorts of tape for this purpose. There are tapes designed specifically for applying to a screen, but I and many other printers just use packing tape, which I get in contractor packs in the paint section of Home Depot. It comes out to $3 or so a roll this way, and I can probably tape 20 to 30 screens with one roll. There will be open areas around your emulsion, so tape the inside edges. If you have more than one design on the screen, tape off the one that you won’t be printing yet. If it’s a very large print, then I tape the bottom of the screen, as a squeegee can tear the tape if it is dragged against it, and without tape on the bottom, ink can come through and ruin a shirt. Also tape any little pinholes that may have been created during washout. You could also use a “blockout pen” to do this.
5. Load and register the screens. If you’re doing just a one-color design and have only one screen, make sure it’s taped and load it into your clamps, leveling it to have even off contact from the platen, and making sure it’s not crooked or anything by comparing it to the grid that you should be drawing on a platen. If it’s a multi-color design, what I do is to take one of the screens and tape its film to it with small amounts of tape at the corners, then make sure my grid platen is sticky enough, load the screen with the film first, level it on the grid, press down the screen well so that the film stays there when I pull the screen back up. Pull off the tape then register all your other screens to it. I get frustrated when the platen isn’t quite sticky enough and the film shifts, and when the platen is so sticky that it is hard to remove the film, sometimes even messing up the platen paper. That burns me up.
6. Do the prints. Load the shirts onto your press and print them. I have a HIX 6/6 press, so it has six platens, and I normally load them all. If you’ve got an oven, do the printing then pull off the shirts and twist and put on the conveyor belt (you’re oven is close enough to your press that you don’t have to move much to put them on the belt, right? It should be). If you’re just using a flash cure to do your final cure, flash the shirts so that they are dry to the touch, stack them and cure them one by one later. If you’re curing with an iron, I feel your pain, you poor thing, you can use your heat gun to dry the prints to the touch and stack for ironing later.
7. Clean up. Scrape up all the ink that you can to put back into the ink jars, unless it’s been a long enough print run that inks have started to stiffen, like if you were printing with opaque inks and they’ve started to get stiff, as you don’t want to use that again. Take your squeegees and goop scoops over to your sink and wash off all the ink. Take your screens to your trash can and remove the tape. Move the screens to your sink and use your spray hose and scrub sponge to remove excess ink, then apply some ink degradient (I use something by Greeneway), and scrub more. You will hopefully have removed pretty much all the ink. Be sure to scrub the stencil after applying degradient too, as this will clean out the ink that can remain as fine lines in the screen. If you don’t clean the stencil well, then the fine lines of ink that stay around the edges of the stencil will harden and persist after reclaiming and coating, so that when you burn that screen the next time, you may have little hair lines in your screen.
8. Sort, box, notify. This is at least what I do: Take all the shirts or whatever you printed and sort them into stacks by size, then box them by folding a half dozen at a time. This seems to really help maximize how many garments can fit in a box, and folding batches of six takes much less time than folding one by one. After they are boxed up, put some of your business cards, some promotional stickers and a thank you note into one of the boxes and notify your customer that all printing is done and that it went well, and they may come to pick up their order. TIP: The oldest trick in the book is to put any bad or just non-perfect prints at the bottom of the box. I pick out a perfect print and leave it folded by itself on the top of the box, as the customer will always pick up a shirt and hold it up to check it out, and it should be a perfect one.
9. Reclaim the screen. After you get the ink and tape off the screen, you’re free to reclaim the screen. My method is to use hot water and spray both sides, then spray chemical reclaimer onto the inside, then the outside, then scrub the outside of the screen (the bottom side, what touches the shirt) really well, then the inside really well. At this point the emulsion will really start breaking down. If it’s not, scrub the outside again vigorously and then the inside again. Then use your spray hose or powersprayer to get the weakened emulsion off, et voila, you have a reclaimed screen, ready for a new application of emulsion after it dries. Store the coated screen in darkness until you are ready to burn it. I keep them in a drying cabinet until they dry, then transfer them to boxes that hold them. I plan to do some modifications to my drying cabinet, mainly adding a dehumidifier, and also build a storage cabinet that could hold 36 screens or so. I still need to design it.
So those are the steps of screen printing. I don’t think I missed anything major. After reclaiming and before applying new emulsion you may want to degrease the screen. I never degrease but most people say its necessary. Flatbed printing is a fashionable and advanced technology today. Flatbed printer is a brand new digital product on the market. We always called it digital flatbed printer.I just don’t do it because it seems to be an unnecessary step, as I haven’t had any problems caused by not degreasing.