Best practices for the creation/evaluation of fingerprint analysis in accordance with the ISO 28199 series

This document gives technical descriptions of X-Y measuring tables together with sample applications, sample evaluations and practical recommendations for visual and metrological evaluation as a supplement to the ISO 28199 series. This document intends to provide further information on this subject to interested parties.

Bonnes pratiques pour la création/l'évaluation de l'analyse des empreintes digitales conformément à la série ISO 28199

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Published
Publication Date
18-May-2022
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6060 - International Standard published
Start Date
19-May-2022
Due Date
19-May-2022
Completion Date
19-May-2022
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TECHNICAL ISO/TR
REPORT 11594
First edition
2022-05
Best practices for the creation/
evaluation of fingerprint analysis in
accordance with the ISO 28199 series
Bonnes pratiques pour la création/l'évaluation de l'analyse des
empreintes digitales conformément à la série ISO 28199
Reference number
ISO/TR 11594:2022(E)
© ISO 2022
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ISO/TR 11594:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Email: copyright@iso.org
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Published in Switzerland
© ISO 2022 – All rights reserved
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ISO/TR 11594:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Review of previous developments ........................................................................................................................................... ..........1

5 General quality requirements for the creation of a standard test panel ................................................2

6 Current evaluation methods ................................................................................................................................................................... 3

7 Selected examples for the graphical presentation of measured quantities from

various measuring tables ........................................................................................................................................................................... 3

8 Test panels ..................................................................................................................................................................................................................5

9 Materials for FAS panels .............................................................................................................................................................................. 5

10 Wedge layers ............................................................................................................................................................................................................ 6

11 Possible methods for creating wedge layers .......................................................................................................................... 7

11.1 Through dynamic path distance............................................................................................................................................. 7

11.2 Through dynamic changing of the quantity of paint (paint flow quantity) .................................... 8

11.3 Through dynamic changing of the tip velocity .......................................................................................................... 9

12 Further information on wedge-shaped coating ...............................................................................................................11

13 Measuring tables...............................................................................................................................................................................................12

14 Current state-of-the-art technology for measuring devices ..............................................................................14

14.1 Film thickness measuring devices ..................................................................................................................................... 14

14.2 Colour-measurement devices ................................................................................................................................................. 15

14.3 Measuring devices for determining surface structure ................................................................................... 15

14.4 Measuring devices for determining mottling .......................................................................................................... 15

15 Monitoring of test equipment..............................................................................................................................................................15

16 Software .....................................................................................................................................................................................................................16

17 Visual evaluation of test panels ........................................................................................................................................................17

17.1 General ........................................................................................................................................................................................................ 17

17.2 Illumination chamber for the visual assessment of standard X-Y measuring table

panels, taking into account the specifications in ISO 3668 ......................................................................... 17

17.2.1 Aim ............................................................................................................................................................................................... 17

17.2.2 Dimensions (example) ................................................................................................................................................ 18

17.3 Possible items of equipment (illumination in accordance with ISO 3668) .................................... 18

17.3.1 Fluorescent tubes ........................................................................................................................................................... 18

17.3.2 Yellow halogen lamp and daylight lamps................................................................................................... 19

17.4 Process steps ......................................................................................................................................................................................... 21

18 Result from interlaboratory testing to demonstrate precision .....................................................................22

Bibliography .............................................................................................................................................................................................................................25

iii
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ISO/TR 11594:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee

SC 9, General test methods for paints and varnishes.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2022 – All rights reserved
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TECHNICAL REPORT ISO/TR 11594:2022(E)
Best practices for the creation/evaluation of fingerprint
analysis in accordance with the ISO 28199 series
1 Scope

This document gives technical descriptions of X-Y measuring tables together with sample applications,

sample evaluations and practical recommendations for visual and metrological evaluation as a

supplement to the ISO 28199 series. This document intends to provide further information on this

subject to interested parties.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 R eview of previous developments

After the successful introduction of this prediction method for the process behaviour of automobile

series paints and an application for a patent in 1994, the ISO 28199 series up to 2009 was developed and

published in the years 1999 to 2009, initially in the form of a EUCAR pre-standard within the framework

of a EUCAR project (from 2006 onwards, originally initiation of a DIN standard – the DIN 55993 series–

which in the meantime has been replaced by the ISO 28199 series).

X-Y measuring tables (scanners) that were innovative at the time were developed to the point of being

ready for series production from the mid-1990s onwards. The first fully automated X-Y measuring table

was put into service in 1996.

After pre-development in the early 1990s, the first measuring tables were subsequently made ready

for series production. Standardization of the evaluation of measurements was very soon demanded by

the automotive industry. The aim was that paint suppliers provide process-reliable and suitable coating

systems to paint users as early as possible in the approval process for new base coats. In particular,

the needs of the automotive industry increasingly demanded the ability to demonstrate process

compatibility already in the design phase for new base coats. Further components of and results from

X-Y measuring tables included not just the demonstration of process compatibility for coating systems

awaiting approval, but also the ability to carry out process compatibility studies for new coating lines,

for example.

A new method was developed to ensure the process compatibility of new paints in base coats already

in advance of the actual paint approval. This method essentially consists of the application of a

film thickness wedge of the base coat (BC, now also a two-layer structure with BC 1 and BC 2) onto

standardized steel sheets that have been coated with a particular coil-coating-PUR paint and that have

a particular defined substrate structure (visual appearance of a very smooth coil-coating painting).

This is followed by coating with clear coat (series clear coat or with a new clear coat that is to be

investigated) with a constant film thickness. The film thickness wedge of a paint system that is to be

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ISO/TR 11594:2022(E)

investigated (e.g. new base coat/paint) covers the range of film thicknesses of the series coating process

that the new paint is to be used in. A sufficiently high number of measurements are carried out with

various optical measuring devices so as to satisfy the requirements of statistical evaluation methods.

The film thickness measurement in comparison with the measurements from the optical measuring

devices is an important control parameter for an X-Y measuring table.

In the next step, suitable laboratory application systems (initially with pneumatic/pneumatic

application, later with special high-rotation bell electrostatic paint sprayguns/pneumatic) were

acquired. Today, modern high-rotation bell processes are simulated. Such is the progress that has

been made, the various existing high-rotation bell and their coating processes can be simulated

with “replacement bells” in laboratory systems in the case of central worldwide approval for various

factories, for example. It was of course initially difficult to transfer the correlation of series coating to

laboratory applications. Ultimately, success was achieved with the aid of so-called “practical fingerprint

panels” also coated onto the bodywork at a suitable location in a frame in series production.

The demands from automotive manufacturers for standardization of evaluation, as mentioned above,

resulted in a European Council for Automotive R&D (EUCAR) project with precisely this aim.

EUCAR is an umbrella body of automotive manufacturers that aims to jointly promote research and

development in the areas of mobility, technology and processes. Suppliers and/or parties from other

sectors also participate alongside automotive manufacturers on projects for these purposes.

The result of this joint project is the former DIN 55993 series, which was published as a draft version in

2006 and which in the meantime has been replaced by the ISO 28199 series.
5 General quality requirements for the creation of a standard test panel

It is important in terms of the predictability of process compatibility that the coating systems to be

investigated are coated/produced in a manner as close as possible to the real process onto the standard

panels of dimensions 300 mm × 570 mm (see ISO 28199-1) in laboratory systems, for example. Suitable

methods for this are described in Clause 9.

The evaluation of the measurement values of various optical measuring devices (e.g. colour, coating

structure, gloss, mottling, haze, sparkling) and the classification of the relevant film thicknesses

provides information about important process characteristics such as colour stability, gloss and

mottling behaviour, and coating structure (e.g. microstructure and ‘orange peel’ texture, depending on

the selected measurement method) of the coating systems to be investigated.
This supplies results that allow conclusions to be drawn regarding:

— the properties of base metallic coats, for example, such as those of the effect pigments that are used;

— the hiding power of paints on coloured fillers, for example;
— the colour tone stability in the process film thickness range;
— the wetting behaviour;
— the sagging behaviour;
— the bubble behaviour;

— re-dissolving by a particular clear coat (series standard clear coat or test clear coat);

— the overspray absorption;
— the pinhole behaviour;
— many other base coat or clear coat properties.
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ISO/TR 11594:2022(E)
6 Current evaluation methods

The system described in the ISO 28199 series and in this document allows conclusions to be drawn

about process suitability for a particular coating process (prediction of process suitability) depending

on various coating systems and/or various substrates and vice versa.
One example in this regard would be the investigation of clear coats:

The clear coat wedge essentially allows conclusions to be drawn about wetting on the relevant substrate

itself and about which clear coat structure is present in a previously defined process window.

The method can also be used in the prediction of process suitability of new base coat paints (BC as a

one-layer coat or BC 1 and BC 2 as a two-layer coat with BC 1 with constant film thickness and BC 2 as a

base coat wedge) with a standard clear coat or with the use of a standard base coat in comparison with

various clear coat systems.
7 Selected examples for the graphical presentation of measured quantities from
various measuring tables

An early initial example from late 1999/early 2000 of a metallic BC paint wedge as a film thickness

profile is presented in Figure 1. The application of the base coat wedge using the old method with

pneumatic/pneumatic application had not yet been fully optimized.
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ISO/TR 11594:2022(E)
SOURCE Reproduced with permission from BMW AG.

Figure 1 — Example from late 1999/early 2000 of a metallic BC paint wedge as a film thickness

profile
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ISO/TR 11594:2022(E)
8 Test panels

Testing the surface quality is a possible method of checking test panels (incoming goods inspection).

This can be carried out using a measuring table with suitable measuring devices.

— Film thickness measurement, to determine the film thickness distribution on test panels.

— Colour tone measurement, to determine a homogeneous colour tone. Important for subsequent

determination of the colour consistency and the process hiding power of base coats or topcoats.

— Structure measurement, to ensure a homogeneous structure.

— Gloss measurement, as a homogeneous reproducible gloss value is important in order to ensure

reproducible wetting.

All these measurements have the aim of keeping the influence of the substrate on the measurement

results of the coated panel as reproducible and minimal as possible.
As an alternative to pure coil coating sheets, plastic panels can also be used.

It is possible that these already have different surface properties or else different surface properties will

be induced, depending on their application purpose. In this regard, both defined cleaning and activation

can be necessary, which can be tested by measurement of the surface energy (ISO 19403 series), for

example. After coating with specified standard materials, the profile values can be measured in order

to monitor and approve the profile properties of the plastics between batches. Analogously to the coil

coating sheets, additional measurement of the colour tone and gloss can also be carried out here.

The film thickness measurement can be carried out using a microscope or else, after prior calibration,

with the corresponding coating material in comparison with the magneto-inductive measurement on

the coil coating sheet.
9 Materials for FAS panels

A so-called wedge panel is created in order to determine the process window of a certain base coat in

a paintshop. The so-called Fingerprint Analysis System (FAS) test panels are available in the materials

of steel (e.g. bright grey coil coating sheet – steel), aluminium or plastic. The FAS panels are moved onto

the X-Y measuring system/table (scanner) for individual measurements either automatically using a

magazine or else manually.

In the case of two-layer base coats, the FAS panels are presented with a base coat (BC 1) applied as a

constant layer and a base coat (BC 2) applied as a film thickness wedge. In the case of “one-layer base

coats”, the single base coat is applied as a wedge, while the clear coat is applied with a constant clear

coat thickness both in the case of the two-layer base coat and of a one-layer base coat. Subsequently, an

evaluation is carried out based on the determined colour and structure values and, depending on the

specifications, on additional measured quantities related to the paints (see Clause 5).

Before this step, attention is to be paid to the transfer/simulation of coating parameters and conditions

in the spray booth/surroundings in series production to a laboratory application system (see also

Clause 5).
Applications of FAS panel include the following:

— Colour tone styling, paint development, product optimization, quality control, optimization of

application processes in the automotive industry. Paint manufacturing industry, strip-coating

industry and industries that employ coating application as automated processes.

— Simulation of the series coating process. The simulation of the series coating process can be

supported by the methods in ISO 28199.

— The test procedure is based on experience that shows that the film thickness, colour/effects and

structure of a coating are important control parameters in the application process, which the main

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ISO/TR 11594:2022(E)

coating properties depend upon directly or indirectly. Additional coating properties such as those

listed under measured quantities (see Clause 5) can identify other optimizations of the coating

process.

— A wedge panel is created in order to determine the process window of the base coat in a paintshop.

Base coat (BC 1), base coat (BC 2) and clear coat are applied to this, for example, and the layer to be

examined is coated in wedge form. Subsequently, an evaluation is carried out in accordance with

specifications based on the determined colour and structure values or other coating properties.

— See the second example of a scanner available on the marketplace for an example and functional

description of FAS software.
10 Wedge layers

The coating of wedge-shaped layers of the coating material to be characterized is important for

fingerprint analysis.

When fingerprint analysis was first introduced, wedge-shaped layers were created using two

pneumatically applied coats, whereby the fingerprint sheet was completely coated in the first hit of

application and only half of it was coated in the second hit of application (see Figure 2). A wedge layer

of satisfactory quality was achieved in combination with the down draft that applied during coating

during and with gravity.
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ISO/TR 11594:2022(E)
Key
1 wedge layer first hit of application
Second hit of application. second hit of application
First hit of application.
Coil coat substrate.
Figure 2 — Creation of a wedge-shaped layer

However, this type of coating (2 × pneumatic) is not usual in e.g. series automotive painting, and as

a result, more process-like application methods were required. There was a focus on the use of

electrostatically supported high-speed atomization, in particular. To meet this requirement, there

was increased use of painting robots in the laboratory area and of highly flexible automatic painting

equipment with high-speed atomizers. As a result, wedge layers in the form of single layers with good

accuracy became feasible.
11 Possible methods for creating wedge layers
11.1 Through dynamic path distance

Figure 3 illustrates a wedge-shaped coating applied by means of dynamic enlarging of the path distance

during the coating step. This is achieved by small path distance at the bottom of the panel and large

path distance at the top. All other coating parameters, such as rotational speed, shaping air and paint

flow, remain constant.
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ISO/TR 11594:2022(E)
Key
1 wedge layer

Figure 3 — Wedge-shaped coating by means of dynamic enlarging of the path distance during

the coating step
Advantage: The brush parameters can be set to typical series values.

Disadvantage: Wedges of satisfactory quality can only be achieved with great difficulty with this

application type as a result of the inhomogeneity of the ESTA-HR spray cone. The membrane overlap is

not constant across the entire coating area.
11.2 Through dynamic changing of the quantity of paint (paint flow quantity)

Figure 4 illustrates a wedge-shaped coating by means of dynamic reduction of the paint flow during the

coating step. This is achieved by high paint flow at the bottom and low paint flow at the top. All other

coating parameters, such as rotational speed, shaping air, paint flow and tip velocity, remain constant.

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ISO/TR 11594:2022(E)
Key
1 wedge layer

Figure 4 — Wedge-shaped coating by means of dynamic reduction of the paint flow during the

coating step

Disadvantage: Wedge quality is only mediocre because the SB50 % value (spray pattern 50 % value)

changes with the change in the paint flow. This disadvantage can be addressed by adapting the air

quantities assigned to the relevant paint quantities (shaping air and/or horn/atomizing air). However,

complete correlation with series parameters is then no longer possible.

The different paint flow quantities for each coating path also result in different atomization behaviour

of the coating material. This can lead to overlapping and/or a change in coating properties that depend

on film thickness.
11.3 Through dynamic changing of the tip velocity

Figure 5 illustrates a wedge-shaped coating by means of dynamic increasing of the tip velocity during

the coating step. This is achieved by low speed at the bottom and high speed at the top. All other coating

parameters, such as rotational speed, shaping air, paint flow and tip velocity, remain constant.

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ISO/TR 11594:2022(E)
Key
1 wedge layer

Figure 5 — Wedge-shaped coating by means of dynamic increasing of the tip velocity during the

coating step

Advantage: Very good wedge quality because the spray pattern does not change as a result of the

constant brush parameters (preferably analogous to series production) and the path distance can be

set to achieve ideal overlapping.

Disadvantage: In certain cases, the tip velocity can be outside of the typical range for series production.

The increasing use of integrated coating processes led to consideration being given to the combination

of two wedge layers on a test sheet (either in the same orientation or else rotated through 180° with

respect to one another). However, it became evident that the reliability of this type of assembly as a basis

for drawing conclusions is very questionable as only a limited number of film thickness combinations

can be evaluated here. It is generally more useful to apply layer 1 with a constant film thickness and

to coat layer 2 onto this as a wedge (or vice versa). This possibly means that the constant layer needs

to be represented by different values on a number of test sheets, but the conclusions drawn relating to

process compatibility will then be significantly more reliable.
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ISO/TR 11594:2022(E)

If highly flexible automatic painting equipment/robots are available, a variant of this type of application

can be implemented. In this case, the tip velocity is varied within a coating path (see Figure 6), which is

not possible with all automatic painting equipment.
Key
1 wedge layer

Figure 6 — Wedge-shaped coating by means of variation of the tip velocity within a coating path

With this application variant, it is beneficial to align the sheet and the coating paths horizontally

with respect to one another for coating and then to turn the sheet in the vertical direction for the

corresponding flash-off times. Coating starts on the right at a low tip velocity and finishes on the left

at a high tip velocity. This results in a film thickness wedge with a high film thickness on the right

and a lower film thickness on the left. The advantages and disadvantages correspond to those of the

application with a constant tip velocity for each coating path above.
12 Further information on wedge-shaped coating

With the use of application parameters that are as close as possible to production line conditions, it is

possible that a stably (±3 μm) increasing film thickness wedge cannot be created with these parameters.

In this case, deviations larger than ± 3 μm is permitted.
Normall
...

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