Silk screening is very easy if you know what you're doing. However, without some instruction by an experienced silk screener, it can be an incredibly frustrating process to learn - a characteristic that I've found out the hard way. Although the instruction booklets that come with silk screening kits are helpful, they often leave out some important practical information, and frankly aren't that good. Because I know all of you E2 noders are chomping at the bit to silk screen your very own Marquee Moon t-shirts, some instructions are just the ticket to get you on your way. This is not a replacement for the comes-with-kit booklet, but a much-needed addition. My one bit of advice to you is do not use the recommended light bulb height and exposure time -- I did, and I burned a hole through my screen!
I will be detailing the photo emulsion process of silk screening in this write up, because it is the most complicated, the most hazardous to your equipment, and the most commonly used method of screen printing. Other methods include cutting stencils and painting on drawing fluid, which you can easily figure out by yourself.
----- First, you'll need... -----
- A kit. Speedball makes a good one, and they sell it at just about any art/craft store. It comes in two flavors, the basic ($40) and the deluxe ($70). The basic kit comes with a couple colors of fabric ink, a screen, squeegee, and photo emulsion. The deluxe kit comes with all that, and more - some other colors of ink, some acrylic inks (good for doing posters, records, etc; bad for doing fabric), and a couple other little goodies. All you really need is the basic, but if you can afford it, you might as well go for the gusto. The deluxe comes with this little instructional video that's totally rokken (as in Dokken).
- A clamp-on shop lamp. You can pick these up at Home Depot, Job Lot, or wherever. They look like an aluminum bowl with a giant nipple clamp attached to the back, if you can picture that. The bowl on my shop lamp is roughly 8.5" in diameter.
- A BBA #1 light bulb. These things are fucking bright, screw into a regular light socket, and are used mainly for stage lights. Although you can use a regular 150 watt light bulb to expose screens, it will take you about an hour; these BBA #1 babies can expose a screen in 10 minutes. Although they're slightly expensive, they're definitely worth the price tag - your screens will expose faster and the result will be better. You can get them at a good photography store. Whatever you do, don't touch the bulb with your bare hands, ever! According to the nice lady at the photography store, oil from your fingers can cause the glass bulb to superheat and explode!
- A piece of roughly 2" thick foam rubber, cut to fit inside your silk screen frame. You can probably pick this up at the craft store when you go buy your screening kit.
- A piece of glass about the size of your screen. During the exposure, the glass and foam sandwich the silk screen and positive image to increase the likelihood of good, crisp edges. The booklet that comes with the silk screening kit will detail this. I would suggest going to Wal-mart, picking up a cheap 9x11" picture frame for $5, and using the glass from that. I would not advise using plexi-glass because it melts at a much lower temperature than glass (trust me, I've melted some before, and destroyed my screen in the process).
- Decent, medium-adhesion masking tape. Pick this up at the craft store where you bought your silk screening kit.
- Overhead projector transparencies for photocopiers and/or laser printers. Transparencies for laser printers will work in printers and in photocopiers (and vice-versa). Whatever you do, don't get ones for ink-jet printers, else you might end up fucking up some equipment. Unfortunately, Staples only sell these in like 100 packs, which you're never going to need. (In my years of screening I think I've probably only used like 30 at the most). You might want try stealing them, if you're up for that sort of mischief.
- Bleach, and an ammonia-free cleaner (I think Greased Lightening works the best) for cleaning up afterwards.
- A nylon bristle brush, as used in dishwashing.
----- Design -----
Okay, so you picked up all that shwag, now it's time to make the design! Make your drawing in two colors, black and white. You are going to make a positive, so everywhere that's black, ink will be printed. For instance, if you draw a smiley face on with black marker onto white paper and follow the remaining steps, you will be left with a silk screen that will print out a smiley face in whatever color you choose. This is hard to explain in words, just check out the booklet that comes with your kit.
You can draw your positive on the computer, or draw it on paper, scratch board it, whatever you feel comfortable with. I usually draw my positives in Macromedia Freehand. Whatever method you choose, the key is getting it onto an overhead projector transparency. If you draw it on the computer and have access to a laser printer, then you're golden, just print out the design on the transparency and make sure the design comes out OPAQUE (hold it up to a bright light to check); if the design is not opaque, run it through there a second time. If you don't have a laser printer, a photocopier will do just fine. Again, make sure the design comes out opaque. Do not attempt to use an ink-jet printer with ink-jet transparencies, because you will have to run the transparency through the printer about 10 times to get the design to come out opaque (trust me, I've tried!). Save yourself the hassle, just use a photocopier!
----- Setting up everything -----
I've found the best place to do this is in the basement laundry room, because it's dark and there's running water in there. A bathroom would work just as well, and a large closet would work too. Just make sure the room you select is light-proof. If you do use a bathroom, make sure you, uh, relieve yourself before starting...
Place the foam on the ground and put the glass somewhere nearby. Next, you're going to want to set up your shop light so that the bottom of the bulb is about 24 inches away from the top of the foam (this is where your silk screen is going to rest). I clamp the shop light onto a cheap $10 easel, which allows me to adjust the height of the lamp with easel (sorry, I couldn't resist). Whatever you use, just make sure the light bulb is 24" above the foam. This is pretty important.
----- Almost exposure time -----
All this is detailed in the booklet, so I'll just briefly skim it
Every time you silk screen, you want to tape up the edges of the screen so no photo emulsion or ink can work its way in-between the screen and the frame. The included booklet has some handy pictures to help you accomplish this feat. I've heard of some people using varnish to permanently attach the masking tape to the frame, but to me, this sounds like a bad idea.
This next part should be done in dim light:
If this is the first time using the emulsion, you're going to want to mix the sensitizer with the emulsion. Next, pour a bead of emulsion across the edge of the screen, and spread the emulsion across the screen with the squeegee. You want the emulsion to completely cover the screen, smoothly and without drips, but not too thinly else you'll end up with little pinholes in your finished product (which, depending on your design, can look rad, or wreck it). After a few tries, you'll figure out the right amount of emulsion to put on there. The thickness (or thinness) of the emulsion can also play a part in this.
Now you're going to want to let that emulsion dry in complete darkness. You'll want it to dry horizontally to decrease drips, and having a fan blowing across the screen really expedites the process. I take two books of the same thickness, and put them under opposite ends of the frame to allow for better airflow over both sides of the screen. The screen should dry in about 20 minutes or so, although the speed of your fan and the size of your darkroom will play a role.
----- Exposure -----
After the emulsion has dried, it's pretty sensitive to light so just keep that in mind.
Once the emulsion is dry (be sure it's completely dry!), bring in your transparency, place the screen face-down on the foam, place the transparency upside-down on the back of the screen, and place the glass over that. Flip on the light (don't look, it's fucking bright) and let everything roast for about 12 minutes. I would suggest leaving the room during this portion of the process, unless you want to be seeing little blue dots every time you blink, but whatever floats your boat...
Again, the bottom of the BBA #1 lightbulb should be 24" from the screen surface, and you should expose the screen for 12 minutes. After wrecking a lot of screens experimenting with different times and heights, this combination works great for me.
Warning: Advanced Maneuver. Skip this paragraph unless you're a fairly confident silk screener. The above time, 12 minutes, works well with my equipment and my style of drawings. Chances are, it will work well for you too. But, if you are doing something very complex, like a halftoned photograph, you've got some experience under your belt, and you have a lot of time to kill, you might want to try experimenting with the time. Remember in photography class when you'd slide a piece of paper off the test strip at a certain interval to determine the proper exposure time? You can do the same thing with the silk screen and a piece of cardstock, then look at the results to determine the best time for your graphic. If the above paragraph made no sense to you, just forget about it; chances are, you don't need to do this.
----- Washing -----
The way photo emulsion works is that everything that light hits gets really hard, while things that light doesn't hit stay soft and water-soluble. So after those 12 minutes of light-exposure, everything around your design is rock hard, while the areas of the screen blocked off by the printer/copier toner are still soft. The soft areas will wash out with water, thus allowing ink to squirt through.
Warning: what you're going to do next is by far the most frustrating part of silk screening. Take your freshly-exposed screen out into the kitchen (dim light helps), get that little sprayer thing on the kitchen sink, and just start blasting the soft, light-colored part of the screen with cold water to get that emulsion out. Scrubbing at the soft emulsion with a nylon scrub brush will also help the screen to open up, but be careful around the edges, else they won't come out crisp. It will probably take you about 5 minutes of blasting and scrubbing to get your design out. And I really do mean 5 minutes. Don't get frustrated if your design isn't opening up immediately. A steady stream of withering profanity also helps.
----- Printing! -----
So you finally got that emulsion out of the screen, now comes the fun part, printing! Put the screen on the shirt (or other printing medium), pour a bead of ink across the screen, above where your design is. Having someone else hold the screen in place (once you get the hang of it, you can do it all yourself) pull the squeegee towards you, dragging the blob-o-ink across the design. Then go to the other side of the screen, pull the squeegee towards you dragging ink back across the design. You don't need to push down very hard on the squeegee, just a little bit of even pressure as you pull; pushing the squeegee down too hard will force the ink through the fabric, and your ink's color will be muted (although if you're going for that American Eagle already-been-worn look, pressing down hard with the squeegee is the way to do it).
Warning: Advanced Maneuver. Skip this section if you are a novice.The amount of pressure on the squeegee is determined by the thread count of the silk screen fabric. If you go out and purchase tightly woven, high thread count screen fabric (16xx), you will have to press harder than if you use a lower thread count fabric (8xx). High thread count yields a nicer result if you're printing on paper, but sucks for printing onto textiles. If you are mostly printing shirts, I would recommend 8xx. Its bigger holes allow the thick textile ink through easier, and you don't have to press so hard, which makes white ink on black fabric much easier to do.
----- Cleaning up -----
Immediately after you're done printing, run some water through the screen to get most of the ink off. You definitely don't want ink drying in there! (If ink does dry in there, I've heard that acetone can get it out, but I've never tried this.) Next, spray on some Greased Lightening and let it simmer for about 10 minutes, scrub all the ink away with a nylon scrubby brush, and rinse with water. Next, you're going to want to soak the screen in bleach for roughly 30 minutes to remove all the emulsion. Scrub hard with the nylon brush and make sure you get all the emulsion out. It might take a second bleach-soak (see below).
Be aware that the sooner you clean the screen, the easier it will be to get the emulsion out. If you expose the screen, print, and clean all in one night, cleanup will be very easy. If you expose, print, and clean over the span of a week, it will be a bitch to clean. If you leave the emulsion on there for a month or more, you'll never get it out and will need to purchase a new screen. (http://www.dickblick.com/zz434/04/products.asp?param=0&ig_id=1717)
Depending on the type of ink you use, you may end up with a very subtle ghost image left on the screen after you're done cleaning. Don't worry, it's just where the fabric ink has stained the silk screen (it's fabric, after all). After a few years of printing, you'll want to replace the fabric; when it comes time, I would suggest replacing it with 12xx (124 threads/inch) multi-filament fabric, which is a good general-purpose fabric for silk screening on a variety of surfaces with a variety of inks. If you are printing exclusively on fabric, you might try 8xx (109 threads/inch) silk screen fabric, which works better with thick fabric inks, but is not as good for printing onto paper.
----- Heat setting -----
If you printed with fabric ink onto fabric, you need to heat-set the ink to prevent it from washing out the next time you do your laundry. To do this, first make sure that the ink is dry to the touch, then toss it into the dryer on its highest heat setting for a while (30 minutes or so). If you don't have access to a dryer, put your iron on the hottest setting (without steam!), and iron away at your design for a few minutes.
----- That's all, folks -----
Be prepared to mess up a few times before you get everything right. For your first design, you want to avoid thin lines, and stick with big patches of color, otherwise you'll get really frustrated really fast. But with a little practice, you'll be churning out "I choked Linda Lovelace" shirts faster than you can say Johann Gutenberg
If you've got some questions, don't hesitate to send a /msg my way.