Hello Juris,
paper type 1 and paper type 2 as well as paper type 4 in the ISO standard are typical
papers with defined values like paper white, gloss and mass per area. There are a lot of
papers in the market that are not in the tolerances or ranges of the specified values.
Most papers behave like the specified papers but there are also papers which are
different. For example a paper type 1 with mass per area 90 g/m2 does not work like a
paper with 115 g/m2 as mentioned in the standard. In such a case you have to define a new
printing condition with new CIELAB values for the primaries and secondary's because it
is not possible to put the same amount of ink on this paper. You have to carefully derive
new density values for such a paper. The same is true for different coatings.
It is not possible for an international standard to reflect or address all the different
properties of papers of the same type in the market. The web-offset printers established
different printing conditions for their different papers and so you have to do this for
your papers if it will be necessary.
Regards
Guenter Bestmann
Dr. Guenter Bestmann
Research and Development Prinect
Heidelberger Druckmaschinen AG
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D-24107 Kiel
Germany
E-Mail: guenter.bestmann@heidelberg.com<mailto:ernst.mustermann@heidelberg.com>
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From: eci-en-bounces(a)lists.callassoftware.com
[mailto:eci-en-bounces@lists.callassoftware.com] On Behalf Of Juris Valdmanis
Sent: Wednesday, February 24, 2010 2:10 PM
To: eci-en(a)lists.callassoftware.com
Subject: [ECI-EN] paper types and target LAB values
Hello dear list members.
First of all I would like to thank everyone who helped me last time I asked my questions!
Your help was valuable!
But now I have more questions regarding printing to ISO.
In ISO documentation there are Lab target values for primary and secondary colors for
different paper types.
As we are sheet-fed printers we are interested only in paper type 1(gloss coated), type 2
(matt coated) and type 4 (uncoated white).
As I understood from documentation (I have only an old english version of ISO 12647-2 and
english is not my native language as you may already realized) all papers what we use for
printing I have sorted in these three types of paper.
But from documentation papers type 1 and type 2 have the same Lab target values for
primary and secondary colors. >From my previous conclusion papers like fine gloss (with
3 coating layers) and rough matt (with only one coating layer) have same Lab target
values.
No problems with type 1 (gloss) papers, as we can get very close to target values and
densities are ordinary.
But for mate papers (type 2) we have to rise densities to get acceptable Lab values. It
could be understandable as paper surface is rougher and you have to apply more color to
get same saturate colors as on paper type 1.
Problem is that higher densities however lead to different problems in postpress as paper
is not drying well and it smears.
Did I understood correct ISO documentation or am I missing something?
And also I did not find answer to another question: Are Lab target values for wet or dry
colors?
Thank you, everyone.
regards,
bebris
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