Banner Making: From Envision to Completion
SILK SCREEN PRINTING:
Vinyl banners that are silk screen printed are banners that are usually printed in high quantity. There are two main types of silk screen printed banners: spot color printing and four color process printing.
Spot color silk screen printing:
Silk screen printing is done by stretching a thin nylon mesh over a wooden or aluminum screen. Each letter/graphic color usually requires a different screen. The mesh is coated with a film or emulsion that is light sensitive. The image is first produced as a film positive and is placed on top of the light sensitive mesh and is then exposed to ultra violet light. The ultra violet "burns the screen". The screen is then washed with a jet of water, which washes away the light sensitive film that has not been "hardened" by the ultra violet light. The remaining is the "stencil" of the lettering/graphic image that matches the letter/graphic that will be printed on the banner. Generally, this screen building stencil process is repeated for each color on the banner. For the first color, the aluminum or wooden frame is fitted on the press using a hinge allowing the screen to be raised and lowered. The screen is raised using this hinge allowing the banner to be positioned under the screen. Ink is placed on top of the front edge of the screen.
Next, a rubber "squeegee" the size of the screen drags the ink across the surface of the screen pushing the ink through the mesh "stencil" of the screen onto the surface of the banner. To repeat the process the squeegee floods the screen again with a return stroke. The banner is sent to dry and the next banner is positioned and printed. After all the banners of one color are printed, the screen is replaced with another screen containing the next stencil color to be printed. Each banner is again positioned under the screen and the new ink color is pressed through the mesh creating the second ink color on the banner. This process is continued until all of the ink colors are printed on the banner. The banners are then sent to the finishing department for stitched hem and grommets.
4 color process silk screen banner printing:
The process for 4 color silk screen printing is similar to spot color silk screen printing. The main difference is that there are typically only four ink colors that are printed (similar to your desktop printer) cyan, magenta, yellow and black. The entire banner will be printed using a combination of only these four colored dots. Each of the four colors of dots needs to be separated out from the artwork to provide one screen for each of the four ink colors. The process of screen making and printing, though it is similar to that of spot color silk screen printing, is more complex and costly because of the difference in how the film separations are prepared.