| Tools for teaching - A visual aids workshop, and instruction manual for health educators |
|Session 7. Project $3: Design/project #4: Planning 7.0|
|Handout 7.7.1 - A silkscreen manual (Supplementary learning materials)|
Silkscreen printing and clean-up can be very messy procedures. Be sure that you wear old clothes or a large apron, smock, or lab coat that completely covers your garments.
Plan to print the black stencil first. This will make registration of the rest of the colors much easier.
The first color run:
1) Cover work table with brown paper or old newspaper.
2) Place silkscreen bearing black stencil on table with hinged end facing away from you.
3) Assemble your materials - ink, masking tape, squeegee, rags, and one or two small pieces of stiff cardboard (these can be cut from an old carton) or a couple of tongue depressors.
4) Stir the ink well with a stick and thin, if necessary, with a small amount of water (water-base ink) or turpentine (oil-base ink). The consistency of the ink should approximate that of a smooth champarado, i.e. a thickness halfway between heavy cream and pudding.
5) Stack the paper on which you are going to print convenient to your work area but not so close to the screen and ink that it will get soiled.
6) Lift the silkscreen frame and position the first piece of paper on the screen baseboard.
7) Lower the frame, checking to make sure that the image is centered on the paper and that margins are equal. Adjust paper as necessary.
8) When paper is in position, raise screen and, without shifting the paper at all, place a cross of masking tape, 2 layers thick, flush with each of the two bottom corners of the paper.
These masking tape guides-will help you to position subsequent pieces of paper so that the image will be uniformly printed on all copies of your poster.
9) Now lower the frame once again and pool about ½ cup of ink across the end of the screen furthest from you.
10) Hold the squeegee firmly with both hands and set it perpendicular to the screen between the edge of the frame and the pooled ink. In one firm, even motion, pull the squeegee toward you, spreading the ink across the screen and forcing it through the open areas of the stencil onto the paper below.
11) Carefully set the squeegee aside. Lift the frame and remove the printed paper. Lay the print flat in an out-of-the-way spot where it can dry.
12) Place a clean sheet of paper on the screen baseboard, positioning it flush against the masking tape crosses. Lower the screen.
13) Walk around to the other side of the table and use the squeegee to pull the ink back across the screen. Set the squeegee aside, lift the frame and remove the second print as you did the first.
14) Continue in this manner, adding more ink as needed, until you have printed the desired number of copies.
NOTE: Plan on printing 8 to 10 more copies than you actually need. These extra copies will serve as "proofs" when you are trying to register the second and subsequent color runs. You are also bound to have one or two mishaps - a few extra copies are insurance that there will be sufficient "good" prints to fill your needs.
15) When you have finished printing the first color, use a small piece of cardboard or a tongue depressor to scrape the excess ink off the squeegee back into the ink container. Scrape up and save the excess ink left on the screen. Cover the ink container tightly and store for future use.
16) Clean screen and squeegee thoroughly (see SILKSCREEN CLEAN-UP).
• The second and subsequent color runs:
1) To print the second and subsequent color runs, set up your work space and materials as you did for the first color.
2) Be sure that prints are thoroughly dry before printing subsequent colors. Generally speaking, this should only take about thirty minutes for water-base inks.
3) Place the screen bearing the stencil for the next color you are going to print on the work table.
4) Lift frame and position one copy of the partially printed poster on the baseboard. Lower screen and adjust paper so that the area to be printed is in the proper relation to the previously printed color. This is called color registration. Use the tight comp (from SILKSCREEN ART PREPARATION, step 1) as your reference.
5) When the paper is in position, lift frame carefully without moving the print.
6) Tape registration crosses to the baseboard flush against both bottom corners of the print as you did for the first color run (see above, step 8). As before, this will make it easier to register the remaining copies. Do not, however, rely entirely on these registration guides. Visually check each print and make whatever adjustments are necessary to align the images before pulling the ink across the screen.
7) Follow the printing technique described in The First Color Run.