Glossary of Terms : Screen Printing

The angle of the dot is the angle at which the dots chain together. The problem with most computer graphics programs is that the angles of the half tones are set for offset printing but not good for screen printing. A lot of computer programs use 45 degrees as the default angle. Actually, 20 - 25 degrees is good for basic halftone work.

Generally used to describe printer resolution, but often used to describe scanner resolution. Obviously the higher the number the better the resolution of the image. By doubling the number the resolution actually becomes four times larger. 300 dpi used to be standard but unfortunately at 300 the edges of an image can still be a little ragged. 600 dpi is now the standard. Most scanners default to 300 dpi when they should really be set much higher when scanning line art.

Most screen printing on garments is done with wet ink going onto wet ink. Certain jobs and most dark garment prints need to have key colors (such as white) dried or cured before another color can print on top of it. On an automatic press, a flash-curing heater replaces one of the print heads. Some jobs also need a short cool-down period before the next color is printed. Therefore, what appears to be a simple six color design with one flash-cure would need a minimum of eight printing stations: six for the colors, one for the flash heater, and one for the cool down. Flash-curing will often slow the production cycle of the job.

A series of large and small dots that represent image areas of a continuous tone image. Continuous tone artwork can be converted into printable halftone dots using a process camera or by scanning into a computer and outputting onto film or paper as a series of dots. Even the photos in magazines are printed as a series of halftone dots. They are just smaller than the ones we use in garment printing.

Commonly used in offset printing, Process Printing uses the four pigment colors of Cyan, Magenta, Yellow, and Black, called CMYK. On garments, many "simple" process jobs are actually more than four colors. Designs with lots of specific color matches and heavy text need separate "spot colors." If the shirt is a light or pastel color, white is also needed. Good process color is much more difficult to do than normal spot colors.