Blocking/Offset

Problem:

Ink is not drying properly.

Solution:

Add faster drying solvents and/or increase air delivery.

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Problem:

Solvents are trapped.

Solution:

Add faster drying solvents and/or increase air and heat delivery. Also check for ink skinning.

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Problem:

Web rewound is too warm.

Solution:

Reduce chill roll temperature.

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Problem:

Rewind pressure on web is excessive.

Solution:

Reduce web tension.

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Problem:

Ink or varnish are over-plasticized.

Solution:

Remake ink or varnish. Add anti-block agent.

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Problem:

Ink or top lacquer is soft or has a low melting point.

Solution:

Remake ink or lacquer.

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Problem:

Web temperature is too low.

Solution:

Increase web temperature.

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Problem:

Moisture condensation appears on chill roll.

Solution:

Check and reset chill roll temperature above dew point.

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Problem:

Ink has lost solubility creating a surface tack. Tacky inks are prone to blocking/offsetting.

Solution:

Add active (true) solvents for resin to remove surface tack.