Capillary Film Troubleshooting Pinholes Dust on exposure glass, film positive or capillary film Capillary film too thin for mesh count Fabric too dry during film application Emulsion incompatible with ink Degreased screen exposed to compressed air Aggressive solvents used on press Clean glass and film positive. Use lint free cloths. Be sure capillary film is free of dust before adhering. Use recommended film and mesh combinations. Rinse fabric just prior to adhering film. Select emulsion suitable for an ink system, i.e. water resistant stencil for water based inks. Avoid using compressed air to dry screens, it may contain water, dust or oil. Use a screen vacuum to speed drying. Replace aggressive solvents and minimize wash-ups. Retard inks to prevent drying in screen.
Poor definition (sawtooth/lack of edge sharpness) or extremely overexposed Contact between stencil and positive poor Film positive edge quality and/or density poor Mesh count too coarse for image detail White mesh scattering light Capillary film fogged (pre-exposed) Capillary film too thin or thick for mesh count Squeegee pressure excessive when mounting capillary film Excess water not removed quickly enough after film mounted Check lamp consistency and level of output Check vacuum. Check vacuum blanket or hoses for leaks. Check bleeder cord position. Check screen frames for warping. Use film with a sharp hard image edge. Ensure film positive has a solid density of 3.5 or higher. Switch to a higher mesh count or finer thread diameter. Switch to dyed mesh and test to determine new exposure. Handle capillary film in yellow safelight. Store in light tight container. Use recommended film and mesh combinations. Use lighter pressure when mounting capillary film. Squeegee excess water from screen immediately after mounting film to wet fabric.
Poor resolution or loss of detail Capillary polyester carrier not removed before exposure Poor contact between stencil and positive Mesh count too coarse for image detail Capillary film too thick for mesh count Film positive density poor Light undercutting from light source White mesh scattering light Stencil overexposed Emulsion on incorrect side of positive Coated screen stored too long Coated screen pre-exposed Film positive layered excessively Remove carrier sheet before exposure. Check vacuum or weights. Check for warped screen frames. Check for leaks in vacuum blanket or hoses. Check for proper bleeder cord position. Switch to a higher mesh count or finer thread diameter. Use recommended film and mesh combinations. Remake film positive with solid density of 3.5 or higher. Point light source too close, move to distance equal to diagonal of the screen frame. Replace diffused light source with point light source. Switch to dyed mesh and test to determine new exposure. Remake film positive emulsion up, right-reading to contact the stencil during exposure. Store coated screens for no more than 1-2 weeks. Store coated screens in dark cool dry area. Store stencil material in light tight containers. Use yellow safe lights around unexposed screens. Re-image positive into one layer of film. Copyright, Screen Printing Technical Foundation Capillary Film Troubleshooting - Page 3 of 9
Premature stencil breakdown on press or extremely overexposed Fabric too dry during film application Capillary film too thin for mesh count Capillary film fogged (pre-exposed) Stencil inappropriate for water-based inks Squeegee pressure excessive Off-contact excessive Floodbar pressure excessive Relative excessive Aggressive solvents used on press Screen tension insufficient Stencil not dry before printing Rinse fabric just prior to adhering film. Use recommended film and mesh combinations. Handle capillary film in yellow safelight. Store in light tight container. Use water-resistant or waterproof stencils for water-based inks. Reduce squeegee pressure. Reduce need for excessive pressure with higher screen tensions and lower off-contact. Decrease off-contact distance. Reduce need for high off-contact with higher screen tensions. Reduce floodbar pressure. Use moisture resistant dual-cure emulsion. Use dehumidifiers to help control press room. Replace aggressive solvents and minimize wash-ups. Retard inks to prevent drying in screen. Use screens with higher tension. Thoroughly dry the stencil prior to printing.
Emulsion soft or washes/peels off mesh during washout Capillary film adhered improperly Film positive clear density too high Follow manufacturer instruction on applying film. Remake film positive with density of 0.3 or less in clear areas. Washout difficult Coated screen stored too long Coated screen pre-exposed Film positive density poor Capillary polyester carrier not removed before exposure Stencil overexposed Store coated screens for no more than 1-2 weeks. Store coated screens in dark cool dry area. Store stencil material in light tight containers. Use yellow safe lights around unexposed screens. Remake film positive with solid density of 3.5 or higher. Remove carrier sheet before exposure. Copyright, Screen Printing Technical Foundation Capillary Film Troubleshooting - Page 5 of 9
Scumming or thin haze in image areas after washout Film positive density poor Stencil washout insufficient Contact between stencil and positive poor Coated screen pre-exposed White mesh scattering light Remake film positive with solid density of 3.5 or higher. Wash out screen thoroughly to remove all unexposed emulsion. Check vacuum. Check vacuum blanket or hoses for leaks. Check bleeder cord position. Check screen frames for warping. Store coated screens in dark cool dry area. Store stencil material in light tight containers. Use yellow safe lights around unexposed screens. Switch to dyed mesh and test to determine new exposure.
Poor adhesion of stencil to mesh Fabric too dry during film application Rinse fabric just prior to adhering film. Capillary film fogged (pre-exposed) Handle capillary film in yellow safelight. Store in light tight container.
Stencil brittle Relative extremely low Stencil extremely overexposed Maintain a 40-60% relative. Capillary stencil patchy Application techniques poor Drying poor Apply even pressure with roll down method. Use flat surface for board mounting method. Wipe the inside edge of frame after roll-down mounting. Dry frame horizontally, substrate side up to protect emulsion from drips and splashes. Air pockets appear during film application Dust/dirt on capillary film Capillary film kinked Fabric too dry during film application Application techniques poor Screen tension insufficient Ensure capillary film is free of dust before adhering. Handle film carefully. Rinse fabric just prior to adhering film. Apply even pressure with roll down method. Use flat surface for board mounting method. Use screens with higher tension. Copyright, Screen Printing Technical Foundation Capillary Film Troubleshooting - Page 8 of 9
Screen image does not match positive size or proportion Frames warped Screen tension insufficient Vacuum pressure too high Positives expanding from heat during exposure Film positive layered excessively Repair or replace warped frames. Use screens with higher tension. Repair any tears or holes in vacuum blanket. Follow manufacturer setting for vacuum pressure. Use more stable film positives. Re-image positive into one layer of film. Reclaiming difficult Stencil locked in from fast-flashing solvents High pressure washer not used Screen stored for extended period of time Reclaiming chemistry incompatible Use safety solvents to remove ink from screens. Avoid acetone, lacquer thinner containing toluene or ketones, and strong screen openers. Use a high pressure washer for reclaiming. Reclaim stencils as soon as possible. Use recommended solvents and chemistry for reclaiming. Copyright, Screen Printing Technical Foundation Capillary Film Troubleshooting - Page 9 of 9