Screen Printing

From RISDpedia

AKA Silk Screening

Materials for Making a Screen:

1. Silkscreen or Fine Mesh
2. Frame (holds the screen)
3. Screen Filler (this blocks the ink from going through the screen)
4. Tape (plastic packing tape, must be water-proof, duct tape can get messy)
5. Ink
6. Squeegee
7. Photo Emulsion

Variations on #3 the screen filler or whatever it is that is blocking the ink can be many things.

-Some people like using paper cut outs to block the screen.

-Others use actual screen filler to block where ink is not wanted. This is usually a liquid that air hardens, and can later be removed with Mr. Clean or other detergents that loosen the filler and then it can be pressure washed off.

-To do photo-silkscreen, you would need light-sensitive emulsion that hardens when light strikes it, allowing any areas that are not exposed to be rinsed off, revealing your image or line drawing. This emulsion would be applied directly to the mesh using a tray or other means. Companies like Speedball sell basic kits for photo silkscreen. Using this method you would need some sort of transparent material to hold the image. Remember that silkscreens do not allow for gradients unless you create the effect of a gradient with lines or dots or whatever you choose. The ink either goes through the screen or it doesn't. You'll also need a dark room to allow the emulsion to air-dry without getting exposed and then a light source and a flat surface to expose the screen with your image/transparency. I'd get a book or have someone demonstrate this process to you. There's lots of little things involved in photo-silkscreen.

When it comes time to actually print, you're going to need some sort of way to keep track of where your image is going to land in relationship to the paper/wall/t-shirt/whatever. This is your "registration" system. I like using clamps to hold the screen. These clamps have a hinge and two flat surfaces that grab onto the screen's frame on one side, they are often called "hinge clamps".

Then the inking and squeegeeing is all about practice. You load your squeegee evenly with ink, then with the finesse of a steady hand and stiff wrist, you run the inked squeegee along the screen where the image is present. You want to have a squeegee that is about the same size as your image to prevent unintentional heavy ink lines on the final image. Then you bring your screen down onto the surface you intend to print, run the squeegee again with ink along the surface, and voila! You've probably made a mess, but don't worry, you'll get the hang of it!

[edit] Reduction Screen Printing

Reduction Screen Printing is done in layers of color or shades of same color. It can be done with different methods but I find this method to be the best. The problem that most people have with Reduction is that you have to think in reverse. Whatever you draw on the silkscreen will block out the ink. This article names photo emulsion as the means to block out ink, but screen filler can also be used.

Note: Extremely Messy Clean up Procedure

1. You have to make sure that you know what layers of the photograph or drawing that you want to screen. I have used acetate to trace on and a thick black pen (Sharpie or Paint Markers) to trace the image so that when you put the acetate on the other side of the screen (not where you put the ink) you can see it. It makes it easier to do the next step. Tip: If you number the shades or color on the original it makes it so much easier to figure out what order of the layers you have to do.
2. Using photo emulsion, you can paint on the silkscreen. You draw with the photo emulsion where you would ink the screen. Make sure that whatever you draw with the photo emulsion is what you plan on blocking out. For example, if you inked a blank silkscreen white, and drew with the photo emulsion, some clouds and let it dry, then printed with a slightly darker color, the clouds would become the color you did before. If you wished to put a tree in and block it out, the tree would become the last color you inked. So on and so forth...
3. Make sure when doing layers that you start with the lightest color first because it will then be easier to block it out later (once you begin to use darker shades or colors). You can do the reverse it just makes it harder. You just have to make sure you think in reverse, wherever you put photo emulsion, it will not print with the next color you use.
4. IMPORTANT : As cited above, to "register" your print you have to make sure that on the board underneath the silk screen that you make marks where you put the original or else it will alter your print and the layers will not come out the way you want them to. To make sure you do not alter follow these steps. ***Note:Make sure you always do about 6 or 7 prints, you will always have a few that are okay, some that are bad and usually a couple that are fantastic.
   1. When finished with inking, make sure you grab any access ink and put it into the right container.
   2. Make sure that you have an old windex bottle filled with water, sponges and a bucket of water right next to the screen. WASH SCREEN ON TOP OF BOARD UNDERNEATH SCREEN. DO NOT REMOVE SCREEN FROM BOARD UNTIL COMPLETELY FINISHED WITH PRINT. Also Note: Leaving ink on Screen will ruin process and you will have to start all over. CLEAN RIGHT AFTER INKING ALL 6 OR 7 PRINTS (Depending).
   3. As you are washing, make sure that underneath the screen there is newspaper because it will soak up all the excess ink. Make sure to scrub and really get the ink off.
   4. Once you are done with that, let the screen dry on top of the board... A hair dryer works but make sure it isn't on high heat because it will melt the screen... (I know from experience)
5. After you are all done washing, the original photo emulsion should be on the screen still. Then you are ready to block out whatever layer you want now and start the process all over again.

Note: If photo emulsion begins to tear up, let it dry and use photo emulsion to go over the parts that tore up.