ISO2846 offset printing ink standard test introduction

- Jul 05, 2019-

It mainly discusses the following issues:

ISO 2846 list of family members

What are the main aspects of ISO 2846-1?

The Lab value of CMYK is also found in ISO 12647-2, but it is different from ISO 2846-1. What is the difference and connection between the two?

Where does the Lab value of CMYK come from in ISO 2846-1 and ISO 12647-2?

What is ISO 2834-1?Why use it?

Why iso2846-1 ink in b value of -4.5 paper color to measure, it seems to b=-2 paper a lot of ah!(from BBS)

Ink test step 1: make color samples (according to ISO 2834-1)

Ink test step 2: determine ink thickness (according to ISO 2846-1 appendix B)

Ink testing part 3: measuring ink color

 

ISO 2846 list of family members

ISO 2846 consists of the following parts, the general standard is called: printing technology - color and transparency of four-color inks

Part 1: sheet-fed and thermosetting web offset printing

Part 2: cold set offset printing

Part 3 gravure printing

Part 4: screen printing

Part 5: flexo printing

We will only discuss the first part, ISO 2846-1.

Why? 

Because I don't understand the other parts

 

What are the main aspects of ISO 2846-1?

In general, the test items and test contents specified by 2846-1 mainly include three parts:

1. Ink layer thickness

2. Color value of CMYK on the spot

3. Ink transparency

The Lab value of CMYK is also found in ISO 12647-2, but it is different from ISO 2846-1. What is the difference and connection between the two?

If we know something about the printing ISO standard, we should know that ISO 12647-2 is the quality standard of printed matter, and ISO 2846-1 is the standard of offset printing ink.Lab values for field CMYK are defined in both standards.

As you can see from the standard data, the difference between the two standards is quite big.What's the relationship between them?

There is a note in ISO 12647-2:

NOTE 1 Conformance to the CIELAB values given in Table 2 usually requires the use of an ink set that conforms to ISO 2846-1 [1] and the printing sequence cyan, magenta, yellow.

translation

Note 1. The CIELab values of various blocks of printed matter should be consistent with the target values in table 2 only when inks conforming to iso2846-1 are used.And the printing color sequence must be blue, magenta, yellow. 

You get the idea.Only ISO 2846-1 inks will allow you to print prints that meet the CMYK field Lab values specified in ISO 12647-2 in actual printing production.

  

Where does the Lab value of CMYK come from in ISO 2846-1 and ISO 12647-2?

Let's start with ISO 2846-1:

First, use standard paper (as specified in appendix A of 2846-1, not the paper we often say Lab is 93, 0 and -3 when printing), make color samples according to 2834-1, and control the thickness of film layer in the following table:

And then you measure it with a spectrophotometer and you get the Lab value.

 

What about ISO 12647-2?

Ok, according to the previous, you have found that your ink is ISO 2846-1, you use this ink to work.There are two ways to test whether the color values in ISO 12647-2 can be obtained, one is by using a printing suitability meter, and the other is by direct printing.

We are only looking at how to test it on the machine here. Here is the method mentioned in appendix A of ISO 12647-2:

A.3 sheet-fed printing

Prepare iso 2846-1 standard sheets for sheet-fed printing. Insert a marked test sheet of approximately the same thickness on these sheets every 100 sheets.Use iso 2846-1 offset printing ink for printing.After printing, adjust the amount of ink so that printing in reference paper mountain blue, magenta, yellow, black solid color after drying in accordance with the relevant provisions of iso2846-1.If necessary, the drying effect of ink color should be established before printing.When printing the rest of the paper, check the amount of ink regularly to keep it constant.After drying, find out the paper to be measured, measure the color data on the paper to be measured, that is, the ink color data of the paper to be measured.If a multicolor beta is used in the printing process, the chroma value of both the primary and overprint colors can be obtained during the test.

In the sheet-fed printing process, for reference paper and insert of the test paper, blanket provided on the ink film thickness is the same.Due to the different roughness of the inserted paper to be tested, the amount of ink transferred from the blanket is also different, so it may interfere with the amount of ink for subsequent printing.However, the amount of ink quickly recovered in the subsequent up to 50 prints. 

Through the above two questions, I believe you have figured out the CMYK color difference between the two standards. 

 

What is ISO 2834-1?Why use it?

We read through ISO 2846-1 and found that it only specifies the thickness of the ink layer on the paper during the test, but how to get a test sample of this thickness?It didn't say.How to do?But it says the following:

"4.2 preparation before the test

4.2.1 printing sheets for chroma evaluation

The evaluation of each color requires multiple proofing tests in accordance with ISO 2834-1, and each test does not have consistent ink thickness.

The original answer in ISO 2834-1, its full name is ISO 2834-1 2006 printing technology laboratory preparation test prints part 1 - paste inks, which specifies how to make consistent with the thickness of the ink layer.

So how does it work?...Don't worry about the official, we can come back later, you can also check the standard itself.

  

Why iso2846-1 ink in b value of -4.5 paper color to measure, it seems to b=-2 paper a lot of ah!(from BBS)

Good question ah, a look at the issue of children's shoes is to test the ink has depth of thinking.I also want to know, but I don't know the experts of TC130, so I can't answer.If there are any brickmen in the jar, I hope you can give me advice.

 

But from my point of view, 2846-1 is the ink standard, it is a separate existence, and 12647-2 itself is not half a dime of the relationship.So in the ink standard test, it defines the standard paper (see ISO 2846-1 appendix A), this standard paper is awesome, not only on the color value Lab requirements, but also moisture absorption, gloss, gram weight, ash, broken H value and roughness, so cattle X paper where to find ah?So, 2846-1 did an AD telling us that a German Scheufelen, APCO II/II glossy coated, wood-free paper from d-73250 Lenningen, is the standard paper.

 

What about 12647-2?Lab value, gloss and ISO brightness are specified only.Printing and production paper. That's a lot of rules.

What do you think is the relationship between these two kinds of paper?- brick to follow the instructions ah...


Ink test step 1: make color samples (according to ISO 2834-1)

Let me tell you a secret: do you know why IGT is so popular?That's because ISO 2834-1 USES the same testing methods as its products.

 

Small steps:

1, add enough ink (to ensure that the ink layer thickness of the first printing spline is greater than the upper limit of ISO 2846-1) to C1 printing suitability device, uniform ink (0 s, not more than 60 s), printing disc inking (15 s, not more than 60 s).

Weigh and note the weight of the printing tray before printing.

We shall adjust the printing pressure (175±25 N/c m for rubber and blanket printing disc, 200±25 N/c m for metal printing disc), place the dielectric plate with standard paper with pre-printed black ink area, and then press together.

Add up and note down the weight of the printing tray after printing, and wash it clean.

Place a clean printing disc on the evenly mixed C1, the printing disc is inked.

 

According to ISO 2834-1, you should record the following data each time:

Weight of plate before printing: M1

Weight of plate after printing: M2

Measure print area: A

 

These values are used to calculate the film thickness of each printed sample. See step 2 for the calculation method.

Ink test step 2: determine ink thickness (according to ISO 2846-1 appendix B)

6 repeat 2 ~ 5 steps, until to obtain a group of upper and lower ink layer thickness value, with different thickness of the ink test sample.

 

How do you calculate the thickness of the film?Let's take a look at the printing standard:

 

4.1.3 evaluation of ink film thickness

The amount of ink transfer should be measured by measuring the quality of the printing plate before and after printing.Print area A is calculated by measuring the length and width of the print surface.The ink transfer rate is expressed in grams per square metre and calculated by the following equation:

C is equal to M1 minus M2 over A

Here:

C represents: ink transfer rate;

M1 represents the quality of the plate before printing;

M2 represents the quality of the plate after printing;

A represents: printed area

Conversion of ink transfer rate C to ink layer thickness requires the use of ink mass density, which is calculated by the following formula:

D = C/p

Annotation:

D stands for: ink layer thickness

C represents: ink transfer rate

P represents the mass density of the ink