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PROCESS |
CHOICE & REQUIREMENTS |
BEAR IN MIND |
REC. VALUES |
| Choice of Paper |
Uncoated paper, to reinforce the message with feeling and character |
Everyone should be aware of how the print looks on the chosen paper. The technical parameters give an indication of how the paper will be perceived. |
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| Choice of Image |
Light images: Repro and film adjustment important.
Heavy images: Repro and film adaptation particularly important |
All colour images, especially ones with many, contrasting colors, come out very well on uncoated paper. |
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| Image Scanning |
Resolution:
– On scanning
– In digital image |
Twice the resolution of the screening (e.g. 2 ?150 lpi/dpi = 300 lpi /dpi). Also adjust the resolution on scanning to the size of the image in print |
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| Production Flow |
Conventional: Image proces-sing and repro at same time.
With profiles: ICC profiles for each image.
PDF & RGB flows: ICC profiles for whole document. |
There are many different types of flow, but production flows are ultimately governed by the techniques available to the business partner being used. |
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| Image Processing |
Similarity with original: Compare with original image
Adapted:What needs to be conveyed? |
As colours are slightly more matt in print, it is beneficial to increase the ink density and definition. Also cleanse any soiling colours. |
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| Screen Ruling |
Paper with high roughness: Choose low to normal screening depending on other adjustments.
Paper with low roughness:Choose normal to high screening depending on other adjustments. |
133 or 150 lpi /dpi generally make for excellent results on uncoated. However, on high roughness papers the screening should be reduced slightly. |
High roughness:
85–120 lpi/dpi
Low roughness:
133 –150 lpi/dpi |
| Total ink cover-age/GCR/UCR |
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Percentages are measured on the film/plate.
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Max 250% |
| Ink Density |
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Plenty of ink should be used, this causes no problems if a high back pressure is used. The density is measured in wet ink. |
C=1,3–1,45
M=1,3–1,45
Y=1,2–1,4
K=1,6–1,8 |
| Spray Powder |
Use a coarse-grain spray powder. |
Fine-grain powder settles in the paper’s structural depressions, and eliminates the air columns required during setting. |
At least 30 micrometres |
| Setting Time |
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Dry printed sheets on low pallets (fewer sheets per pallet) to avoid smudging. Setting times are shorter after well-executed repro and high back pressure. Heavy images take longer to set. |
In some cases 24-48 houres may be required |
| Dot Gain |
Paper with high roughness: Very high dot gain
Paper with low roughness: Very high dot gain
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Compensate for very high dot gain on uncoated paper. Dot gain is always greatest in the medium shades. In the lightest areas, the dot can be set at 0% |
High roughness: Lightest area 0% Medium 25–40% Darkest 85–90%
Low roughness: Lightest area 0% Medium 15–30% Darkest 85–90% |
| Back Pressure |
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It is essential always to increase the back pressure when printing on uncoated, to press the ink into the paper. |
Min 20-40 micrometres, ideally more! |
| Scoring |
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For grammages of over 150 g/m² scoring may be required, especially if images run across a fold or wood-containing paper is being used. Scoring is always required on papers of over 170 g/m². |
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