SCREEN PRINTING PREPRESS & INK DYNAMICS
Screen Printing Mesh Tension & Off-Contact Prepress Guide
In screen printing, image clarity, dot gain control, and color registration are dictated by mechanical mesh tension (measured in Newtons/cm) and off-contact distance. When a screen is properly tensioned, the mesh releases instantly behind the squeegee, leaving a razor-sharp ink deposit without dragging or smearing.
Screen printing is a peeling process. As the squeegee pushes ink through the mesh openings onto the substrate, the mesh fabric stretches down to make contact. Immediately after the squeegee blade passes, the tensioned mesh must "snap off" vertically away from the wet ink film.
Off-contact is the resting gap between the underside of the screen stencil and the garment platen:
Target Off-Contact:
- High Tension Mesh (25-30 N/cm): 1.5 mm - 2.0 mm (1/16 inch)
- Medium Tension Mesh (18-22 N/cm): 2.5 mm - 3.5 mm (1/8 inch)
- Loose / Static Frames (< 15 N/cm): Requires excessive 4.5 mm+ gap, causing severe image elongation and distortion.
A vector line cannot be printed finer than the spacing of the threads supporting it. The empirical rule for vector film prepress is:
Minimum_Vector_Stroke = (1 / Threads_Per_Cm) * 2.2
- 110 Mesh (43 T/cm): Min Stroke = 0.60 pt (0.21 mm) | Max Halftone = 30 LPI
- 156 Mesh (61 T/cm): Min Stroke = 0.35 pt (0.12 mm) | Max Halftone = 45 LPI
- 230 Mesh (90 T/cm): Min Stroke = 0.25 pt (0.09 mm) | Max Halftone = 60 LPI
- 305 Mesh (120 T/cm): Min Stroke = 0.18 pt (0.06 mm) | Max Halftone = 75 LPI