| Cause | Solution |
| Over-exposure. | • Adjust exposure time (use an exposure calculator). |
| Stencil pre-exposed to excessive UV light. | •
Use safelight in drying and pre-exposure areas. • Check for light leakage. |
| Positives not dense enough. | • Re-evaluate film processing. |
| Coated screens subjected to excessive heat (diazo types). |
• Do not dry at temperatures exceeding 35°C. |
| Poor contact between the screen and film positive. | • Check vacuum contact. |
| White mesh causing ‘light scatter’. | • Use dyed mesh. |