30 November 2008

screen printing (and miscellany)

screenprinting was once called silkscreening, but nowadays it is often a synthetic rather than silk used on the screens. the basic concept is that you create a stencil, but it should be more durable than if you made a stencil from paper or cardboard and is used for multiple copies or printing on fabrics. and with access to technology, it should be a simple process. i know i know--access sometimes is hand in hand with privilege, but please remember who i am.
screen printing can be used for all sorts of projects for which you may need to make multiple copies: fliers, cards, posters or anything your imagination lets you do. plus, it can be a relatively cheap way to have color printing and once you are a bit used to it, you will know how to produce dandy fx onto your project.
here, i will be doing the cover to a tiny book.

your screen...screen frames can be made from wood, picture frames, etc. i'm sure you are inventive enough if you are going to do it yourself. for the screen part silk will work; there is also mesh that gets sold. or aquired. the higher the mesh count, the finer the holes to pass the ink through. a standard mesh count is around 110-120 for screenprinting. or, you can buy a screen where the material is already attached to a frame.

i was a bad doobie and didn't clean my screen. ideally, i would have screens with images fixed upon them or i would clean them right away. i remembered i didn't even use this screen last time as it's in bad condition from early use. so i cleaned it and opted not to use it. i chose an extra screen that is currently available for my use.

i put masking tape on both sides of the screen. it makes for easier clean-up.
next, i put some photo emulsion into a scoop designed to spread it across a flat area and cover the screen with a thin smooth layer of emulsion.

the emulsion is light sensitive, so don't leave the bottle sitting around with the cap off and put the screen in a dark place to dry.
since this takes time, i use the time in between trying to accomplish other tasks for this book.
i will do the foolish task of printing on black. so i take my cardstock(i put a couple extra in to allow for mess-ups) to the industrial paper cutter and with one fell swoop my stack is done. this paper cutter has a blade that drops down when two buttons are simultaneously pressed (hey, just like working in a factory!) and the other scraps of paper buffer the bottom so all my sheets will have a clean cut(that's just how i have learned to work with this cutter). i would otherwise use a smaller paper cutter, scissors, or most likely, a knife & ruler.

now, back in the day, i did things to size for a photocopier. nowadays i can have multiple pages on a file on my little memory stick for the computer.

in this production lab, i happen to have access to a copier machine. otherwise, you can take your thumbdrive to a printer. i imagine this could be a headache as i thought my file was correct, but test prints showed something was off just a little with computer settings, and i'd have to find the discrepancies in some step of creating the file. so, i fix whatever settings i need to and start printing!

i then take that stack to the paper cutter of the future...

now my screen has had time to dry and i prepare my transparencies. if i was a little more anal about this, i'd have it on file so if i ever lost it, i could print out a new transparency. in defense, thumbdrives can go missing too. basically i took my bottle of black and inked right on the transparency. tracing vellum can also do the trick, but i like the clear sheet because if i don't like a line, i can wipe it away with a tissue and spit. since the images are small, they can all fit on this one screen. i also put some tape along the edges and in corners that is sticky-side up so the transparencies will stay in place. this would probably be more crucial with more complex images. it also lends to making sure the images are that much closer to the screen.

(the tracing paper, you can use this instead)

(tape in the corner)

think of this next step as a sort of picture developing. there is a layer of the photo emulsion on the screen. any areas that are "blacked out" will block light exposure in that area. a light table is great for this, but if you don't have one in your living room, you can build one. i think you'll need a non-standard lightbulb, which could ordered on this here interweb(and other materials, if you cannot find them locally).
exposure times can take some getting used to. over- or under-exposing your screen by just a couple minutes can make a difference. the time for the table i'd been using had been around 18 minutes, but now there's this sign:

so i set the screen on the table, cover the other side with black paper (so the light doesn't reflect around to where i do not want light exposure) and set weight upon it all. i also set a timer and then start the exposure.

in the meantime i run up to get some newsprint for my cheap liner paper(i do enjoy a bit of fanciness) and cut that to size while waiting.

when the exposure is over, wash out the unexposed places in the screen. it should come out clearly, only the mesh should be in those areas you wish to print through. if there are fine lines you can check it by holding your screen in front of a light to see if the light comes through clearly.
a basin sink or hose comes in handy. here there is one of the sprayers used by dishwashers in restaurants. i've covered up the other portion of the screen so i can just print some of the images.

next comes registration. it is good if you've got a beater table that you can affix hardware to, or a flat board. for years i'd keep random hinges i'd come across in order to build up a cache of supplies for attaching frames to boards.
anyway, here there are some nifty screw clamp hinges attached to the table top. put the screen in your hinges and see where the image falls and figure out where on the paper it will be printed.
some folks like to create tabs to slip their sheets into. i've never found it to be accurate enough. so i merely line tape where i want my edges and that is usually precise enough for me. do what works for you. the first round of registration has more wiggle room than subsequent rounds, which need a bit more tweaking around the alignment.

it's good to do a test copies. plain/scrap paper is cheaper than the cardstock. so put some ink on the screen

and spread a layer of it over the image area with a squeegee. be careful not to apply much pressure here. this is just to cover the area, not to push the ink through.

now pull the swkeejee over the area, with pressure, so the ink goes through the open areas. look at your print!

and honestly, the screen did not come out as good as i would like. so i take some photo emulsion remover and clean off the screen.

i will have to start over, but next time i will have the other parts of the book ready already and will get to do other things during the wait times.
hopefully this is helpful if you have some sort of interest in print process. if you have questions, ask! i may have missed the inclusion of something.
i am also not the #1 expert on all things screen printing, but i want the information to be accessible, especially the visual of it. i've seen silkscreening steps in zines, but mostly in print with a couple diagrams, which can be overwhelming, depending upon how one processes information.
if i am able to have this camera again, i will show some more when i really do my printing.
stay tuned!

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