Mottled Print

Problem:

Substrate is poor or marginally treated.

Solution:

Check and adjust treatment level or change stocks.

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Problem:

Surface of substrate has holes.

Solution:

Check substrate and reduce ink viscosity for better wetting. Consult your substrate supplier.

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Problem:

Surface tension of ink is not low enough to properly flow out on substrate (Seen mostly in aqueous inks).

Solution:

Reduce surface tension of inks by adding wetting agents.

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Problem:

Impression between plate and substrate is too low.

Solution:

Increase plate impression and check print appearance.

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Problem:

Sticky-back tape is too soft.

Solution:

Use hard tape for solid print areas when possible.

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Problem:

Ink viscosity is too low.

Solution:

Increase ink viscosity.