For most printing I've found 18"x24" screens do well; with them I can usually fit two pieces on them, or one large. It never hurts to have a little extra space. You can buy screens with either a wood or metal edge, in truth it doesn't matter. What you do have to watch though is your mesh count. The mesh count is kind of like the dpi of your silk screen, the higher the mesh count the tighter the threads are woven together. But a higher screen mesh is not always better! A higher mesh count means the threads are tighter, thus you cannot push heavier inks through them (the viscosity of inks varies on type and color). So buy a small range of screens to suit a variety of jobs, I recommend 1bout 150 as a good medium. The tension of a screen is also important, if the silk shifts too much you can lose registration, but this won't happen for quite awhile if you take care of your screens.

The process of coating a screen with emulsion is hard to explain with text, but here goes nothing. First off an emulsion scoop does wonders, but you can manage to do it without, the basic thing you need to accomplish is to thinly and evenly coat both sides of the screen. Here is a diagram of the action of coating the screen. You want to coat both sides with a pass of the emulsion, then go back and scrape off any excess emulsion back into the scoop. After that you need to let the emulsion dry in a dark place, preferably over night, but you can put a fan on the screen and do it in an hour or so if rushed. Also dry them with the screen side down, this means either making a drying rack or putting tacks (or any other material to lift the screen) under it.

Making your film

You need to make a film positive of your artwork before you can expose your screen. You will need to make color separations of your work, and make each seperation black for printing. Here is the artwork I will be using for the remainder of this tutorial, and here are the separation printed on overhead acetate. You can output film on your own inkjet or laser printer, or if you have cash to throw at a particular project you can get film made; which is more costly (about $10) but yields much nicer quality. But if you are poor like me and an inkjet is the most economical thing available it is probably best you print two negatives and double them up (using tape) so the black is more opaque.

Exposing your screen

This step can easily cause you a lot of grief; I know it did to me, but here is my process of exposing my screens. First off I temporarily put my screen on the press, and then tape my artwork down. Then you put the screen and artwork down on top of a black background (black matte board works perfect), here is a diagram. I use a 300watt incandescent bulb with a shop light reflector to expose my screens for 12 minutes at 20" above the screen. There are no hard and fast rules to exposure times and distance, unless you buy a kit from an art store or buy a commercial exposing unit. After you have exposed your screen the next step is to wash out the negative. The best way to do is a pressure washer in a spray booth, but if you're not so lucky to have these things you can build a high pressure nozzle. To build on of these you basically just need to go to Home Depot and raid their plumbing section to find a hook up that will attach to you bathtub or sink, attach it to a dishwasher pressure hose and finally about the smallest opening you can find (essentially this focuses the force of your shower to about 1/8th of an inch). I really recommend making something that makes a great amount of pressure to spray out your screens, I've tried it in the past without and it was a real problem. So once you've built one of these you'll first want to just kind of get the screen wet and let the water soak in for about a minute, this will loosen the unexposed emulsion. After a few seconds of being wet your artwork should become slightly visible, then just let loose and blast any emulsion out that is not supposed to be there, like so. If you find you blow out too much emulsion then next time expose your screen longer, if it is a real bitch to get any of the emulsion out then shorten your exposure time. Once you are happy with how the negative of your artwork looks then set it out to dry, you can put on a fan on it to dry it faster.

Once dry you're not quite ready for the press, you should always check for pin holes. Pinholes are areas of the emulsion that accidentally washed out that should not have. You do not need to worry about every single pin hole, but find the ones within your artwork and with in about a one inch perimeter of the artwork. The reason you don't need to worry about the ones too far out from the artwork is because you will be taping off those areas.