Emulsion & Capillary Film Troubleshooting Guide
Poor definition (edge sharpness) or "sawtoothing" (irregular printing edge):
| Possible Problem | Solution |
| Poor contact during exposure | Check vacuum |
| Underexposure | Perform Step Wedge Test |
| Light scattering | Use dyed fabric |
| Insufficient washout | Wash from both sides |
| Poor buildup of emulsion | Improve coating technique |
| Fabric too coarse | Use higher mesh count |
Stencil Softness:
| Possible Problem | Solution |
| Improper mixing of sensitizer | Dissolve sensitizer thoroughly, mix well with emulsion |
| Underexposure | Perform Step Wedge Test |
| Emulsion too old | Review storage guidelines |
| Positives "yellowed" | Use new positives |
| Excessive hummidity | De-humidify area, increase exposure |
Open-Area "Haze":
| Possible Problem | Solution |
| Positives lack density | Use new positives |
| Poor contact during exposure | Check vaccuum |
| Light scattering | Use dyed fabric |
| "Pre-exposure" of coated screen | Use safelights; store coated screens in dark |
| Over/underexposure | Perform Step Wedge Test |
| Insufficient washout | Check washout procedure |
Emulsion washes or peels away during washout:
| Possible Problem | Solution |
| Coating not uniform | Upgrade fabric stretching and coating procedure |
| Improper mixing of sensitizer | Dissolve sensitizer thoroughly, mix well with emulsion |
| Underexposure | Perform Step Wedge Test |
| Improper fabric preparation | Degrease all fabric; roughen and degrease synthetics |
| Washout temperature too high | Washout below 100° F |
| Emulsion too old | Review storage guidelines |
| Emulsion not dry before exposure | Dry screen sufficiently; use screen drying cabinet |
| Excessive humidity | Increase exposure; dehumidify shop |
Pinholes appear after exposure and washout Pinholes/Fisheyes appear before exposure:
| Possible Problem | Solution |
| Dirt and dust settling on drying emulsion | Dry in dust-free environment |
| Dirt on positive or contact glass | Wipe positives; use window cleaner on contact glass |
| Improper fabric preparation | Degrease |
| Shop dirt and dust | Housecleaning overdue |
| Wet mesh | Dry mesh |
| Dirt and dust settling in coater or emulsion container | Cover coater and emulsion |
| Coating stroke too fast | Slow down; turn screen 180º after each stroke |
Pinholes On-Press:
| Possible Problem | Solution |
| Air trapped during mixing | Allow 1-hour (minimum) for de-bubbling on mixed emulsions |
| Poor coating procedure | Upgrade coating method |
| Underexposure | Perform Step Wedge Test |
| Incompatible ink or washout solvent | Use solvent-resistant emulsion |
| Washout solvent or solvent ink contain water | Avoid solvent storage in large drums (condensation) |
| Frit/pigmented inks; rough substrate | Assuming proper coating and exposure, use more abrasion resistant emulsion such as FX88 |
Details remain closed after washout:
| Possible Problem | Solution |
| Coated screen stored too long | Use freshly coated screen |
| "Pre-exposure" of coated screen | Work under safelights; store coated screens in dark |
| Drying temperature too high | Dry below 104º F |
| Overexposure | Perform Step Wedge Test |
| Poor contact during exposure | Check vaccuum |
| Poor positive | Check density |
| Light scattering | Use dyed fabric |
| Poor light source | Use finer mesh; use faster-exposing emulsion; upgrade light source |
| Incomplete washout | Wash very thoroughly from both sides |
| Light source too close | Where possible, min. exposure distance should be 1½ times image area diagonal |
