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

 

 

 

 

 

 

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