Tech Tip: Trouble Shooting Guide
Print Density Control
| Problem: |
Printed Sheets show colour variation from sheet to sheet during the run. Ink film densities are very unstable. |
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| Causes: | Low ink level in the fountain Improper roller setting Ink Emulsification Ink backing away from the "fountain" roller Roller Stripping Contaminated ink fountain – dust, grit, etc. |
| Solutions: | Keep ink fountain full to maintain head pressure Reset rollers Decrease water or add heavy body varnish Agitate ink in the fountain or increase ink flow Deglaze the rollers Remove ink, clean fountain, replace with fresh ink |
Print Mottling
| Problem: | Print Density is Uneven |
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| Causes: | Too much impression Too much ink being carried Low viscosity ink may look mottled on papers with uneven holdout On some stocks, transparent inks will show more mottle |
| Solutions: | Check Blanket Impression and plate to blanket pressure Run a stronger ink to permit a thinner film Higher viscosity ink will have less absorption and reduce mottle Use a more Opaque ink |
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- Clive Harper
