What is Screen angle?
The rotation angle of a halftone dot grid. In multi-color printing, each color uses a different angle to prevent moiré interference patterns.
In detail
Screen angle is the rotation of the halftone dot pattern relative to horizontal. Standard CMYK angles (75°/15°/0°/45° for K/M/Y/C) are designed so dot grids don't align between channels. Misaligned angles produce dot-rosettes (small flower-like clusters) that the eye blends; aligned angles produce visible moiré (rippling interference patterns). Spot-color screen printing uses 22.5° as the dominant angle and offsets secondary colors by 30° (making 52.5°, 82.5°, 112.5°). Choosing screen angles is largely automated in production software but requires manual review for designs with strong directional elements (stripes, gradients) where standard angles can clash.
Example
A four-color screen print of a floral: navy at 22.5°, coral at 52.5°, sage green at 82.5°, gold at 112.5°. The four halftone dot grids interlock at offset angles, producing rosettes the eye blends into clean color rather than moiré stripes.