Screen Print Color Separation

Spot Color Assignment: Convert full-color artwork to Pantone swatches with automatic color reduction.

Underbase Layer Generation: Calculate white underbase coverage for dark garments automatically.

Registration Mark Placement: Add crop marks and color bars to every separation for accurate screen alignment.

1. Color Mode: Spot colors (Pantone), not CMYK process. Each color = one screen.
2. Resolution: 300 PPI for halftones, vector preferred for solid areas.
3. Underbase: White ink printed first on dark garments, blocks fabric color from showing through.
4. Registration Marks: Crosshairs outside print area, printed on every screen for alignment.

1. Analyze Artwork: Count distinct colors. Gradients require halftones.
2. Reduce Colors: Merge similar shades to minimize screen count (4-color max for manual presses, 6-8 for automatics).
3. Assign Pantone: Match each color to a Pantone swatch for ink mixing.
4. Create Underbase: Generate white layer that covers all colored areas on dark garments. Choke it 0.5-1mm to prevent halo.
5. Set Halftone Angles: Use 22.5°, 45°, 67.5°, 0° to avoid moiré patterns between overlapping screens.
6. Add Registration: Place crosshair marks 10mm outside print boundary, same position on every separation.

Light Garments: No underbase needed if fabric is white or pastel.

Dark Garments: Full white underbase under all colors. Print underbase first, flash cure, then print colors on top.

Choke the Underbase: Make it 0.5-1mm smaller than the color layers so white doesn't peek out at edges.

Selective Underbase: For designs with large solid areas, only underbase the colored regions to save ink and prevent stiffness.

Line Screen: 45-55 LPI for manual presses, 65-85 LPI for automatics. Higher LPI = finer detail but harder to print.

Dot Shape: Round dots for general use, elliptical for smooth gradients.

Angle Assignment: Each color needs a unique angle to prevent moiré. Standard angles: C=22.5°, M=75°, Y=0°, K=45°.

Minimum Dot: 5% for manual presses, 3% for automatics. Smaller dots wash out during exposure.

Each screen adds setup time and cost. Reduce colors without sacrificing quality

• Merge similar shades (navy + royal blue → single blue).
• Use overprinting: print cyan over yellow to create green instead of a separate green screen.
• Consolidate small details into the darkest color.
• Eliminate outlier colors that appear in <5% of the design.

Crosshairs: Two perpendicular lines forming a + symbol, 3-5mm long.

Placement: Minimum 10mm outside the print boundary, same position on every color.

Color Bars: Small squares of each spot color printed outside the image area for ink density verification.

Film Positives: One black film per color, printed at 1200-3000 DPI. Black areas block UV light during screen exposure.

Film Orientation: Emulsion side down (ink side touches the screen during exposure).

Screen Mesh: 110-160 mesh for general printing, 200-230 for fine halftones, 60-86 for opaque white underbase.

Moiré Patterns: Overlapping halftones at the same angle create visible interference. Use proper angle separation (15-30° between each color).

Registration Drift: Screens misalign during printing. Add trap (0.25-0.5mm overlap) between adjacent colors to hide gaps.

White Halo: Underbase extends beyond color layers. Choke the underbase by 0.5-1mm.

Lost Detail: Halftone dots too small for the mesh count. Use coarser LPI or higher mesh count.