A Preface
ISO (International Organization for Standardization) is a global federation of national standards bodies (ISO member bodies). The development of international standards is usually carried out through ISO technical committees. Each member group interested in the subject on which a technical committee has been established is entitled to be represented on the committee. International organizations, governments and ngos that liaise with ISO are also involved in this effort. ISO works closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

Part 1 of the ISO/IEC Directive describes the procedures used to develop this document as well as those used for further maintenance. In particular, attention should be paid to the different approval criteria required for different types of ISO documents. This document has been drafted in accordance with the editorial rules of Part 2 of the ISO/IEC Directive (see iso.org/directives).

Please note that certain elements of this document may be the subject of patent rights. ISO is not 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 profile and/or in the list of ISO patent claims received (see iso.org/patents).

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

Any trade names used in this document are provided as information for the convenience of users and do not constitute an endorsement thereof.

Voluntary interpretation, related standards and conformity assessment related ISO specific terminology and express the meaning of and the ISO in the technical barriers to trade (TBT) adhere to the principle of the world trade organization (WTO) information, please see the iso.org/iso/foreword.html.

This document is prepared by Technical Committee ISO/TC 35, Paints and varnishes, SC 9, General test methods for paints and varnishes.

The fifth edition eliminates and replaces the fourth edition (ISO 2808:2007), which has been technically revised. The main changes from the previous edition are as follows:

Terms and definitions have been updated to ISO 4618 and ISO/IEC Guide 99;

— Revised principles;

— Add a white light interferometer as method 6C;

— Added the terahertz method as method 11;

– The existing methods have adapted to the current situation of metrology;

— Revised characteristics of methods and procedures in Appendix A;

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

– Information on the accuracy of each method in Appendix A has been adjusted to current standards;

— Updated references to test criteria and structural criteria in Appendix A;

— The original Article 7 measurement of film thickness on rough surfaces has been moved to Appendix B;

– Added Appendix C on factors affecting measurement accuracy when measuring wood.

Any feedback or questions on this document should be directed to the user’s national standards body. A full list of these agencies can be found at www.iso.org/members.html.

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

Introduction
This document consistently enumerates the individual coatings applied in multilayer systems by referring to the first coating applied on the substrate as coating 1. Some other criteria refer to individual test methods, listed in reverse order.

1 Scope of application
This document describes the method used to measure the thickness of the coating applied to the substrate. The method used to determine the thickness of wet film, dry film, and uncured powder layer is described.

For each method described, this document provides an overview of the field of application, existing standards, and precision.

Information for measuring the thickness of the film on rough surfaces is given in Appendix B.

Information on measuring the thickness of wooden substrate films is given in Appendix C.

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

2 Normative reference documents
When the following documents are referred to in the text, part or all of their contents constitute the requirements of this document. For dated references, only the cited version applies. For undated citations, the new version of the citation document (including any revisions) applies.

ISO 3611, Geometric Product specification (GPS) — Dimensional measuring devices: micrometers for external measurements — Design and metrological characteristics

ISO 4618, Paints and varnishes – Terms and definitions

ISO 8503-1, Preparation of steel substrates before painting and related products-Surface roughness characteristics of sandblasted steel substrates — Part 1: Specification and definition of an ISO surface roughness comparator for evaluation of sandblasted surfaces

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following shall apply.

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

– ISO online browsing platform: iso.org/obp

– IEC Electropedia: available at electropedia.org/

3.1 Film thickness

The distance between the film surface and the substrate surface

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.2 Wet film thickness

The thickness of the wet coating material just applied, measured immediately after application

3.3 Dry film thickness

The thickness of the coating left on the surface after the coating is hardened

3.4 Uncured powder layer thickness

The thickness of the powder coating material just applied, measured immediately after coating and before baking

3.5 Related surface area

A part of an object that is or will be covered by a coating and that the coating is required for its maintainability and/or appearance

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.6 Test Area

A representative part of the relevant surface area, within which an agreed number of single measurements are taken as spot checks

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

3.7 Measurement area

The area where a single measurement is made

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

3.8 Minimum local film thickness

The lowest value of the local film thickness found in the relevant surface area of a particular specimen

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.9 Maximum local film thickness

The maximum value of the local film thickness found in the relevant surface area of a particular specimen

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

3.10 Average film thickness

Arithmetic mean of all individual dry film thickness (3.3) in the test area or weight determination of thickness

Entry Note 1: The measurement of this attribute is only used for the extended evaluation of film thickness measurement; See article 7, k) and l).

3.11 Calibration

Under specific conditions, first step, the operation of establishing a relationship between the quantity value provided by the measurement standard with measurement uncertainty and the corresponding indication with relevant measurement uncertainty, second step, using this information to establish a relationship to obtain the measurement result of the indication

Note 1: Calibration can be expressed in statements, calibration functions, calibration plots, calibration curves, or calibration tables. In some cases, it may include an additive or multiplicative correction for an indication with associated measurement uncertainty.

Note 2: Calibration should not be confused with adjustment of the measurement system, often erroneously referred to as “self-calibration”, nor with calibration verification.

Entry Note 3: Typically, the first step in the above definition alone is considered calibration.

[Source: ISO/IEC Guide 99:2007, 2.39]

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.12 Confirmation

Provide objective evidence that a given project meets specific requirements

Example 1: Confirm that the required given reference material is uniform for the relevant quantity values and measurement procedures until the mass of the measured part is 10 mg.

Example 2: Confirm that the performance characteristics or legal requirements of the measurement system are met.

Example 3: Confirm that the target measurement uncertainty can be met.

Note 1: When applicable, measurement uncertainty should be considered.

Item Note 2: Items can be, for example, processes, measurement procedures, materials, compounds, or measurement systems.

Note 3: Stated requirements can be, for example, meeting the manufacturer’s specifications.

Entry Note 4: Statutory metrological verification as defined in VIML, and conformity assessment in general, involves the inspection and marking of measurement systems and/or the issuance of verification certificates.

Note 5: Validation should not be confused with calibration. Not every verification is a verification.

Note 6: In chemistry, verifying the identity of the entity or activity involved requires describing the structure or nature of the entity or activity.

[Source: ISO/IEC Guide 99:2007, 2.44]

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.13 Reference R M

The material, sufficiently homogeneous and stable with respect to the specified properties, has been determined to be suitable for its intended use in measurement or inspection of nominal properties

Entry Note 1: Examination of nominal attributes provides nominal attribute values and associated uncertainty. This uncertainty is not measurement uncertainty.

Note 2: REFERENCE MATERIALS with or without specified quantity values can be used for measurement accuracy control, while only REFERENCE materials with specified quantity values can be used for calibration or measurement trueness control.

Note 3: “Reference materials” include materials embodying quantitative and nominal characteristics.

Example 1: Sample reference with quantity:

a) water of specified purity whose dynamic viscosity is used to calibrate the viscometer;

b) Human serum without a quantitative value for the mass concentration of intrinsic cholesterol is used only as a control substance for measurement accuracy;

c) Fish tissue containing the specified mass fraction of dioxins to be used as calibrators.

Example 2: Example of reference material embodying nominal characteristics:

a) a color card showing one or more specific colors;

b) a DNA compound containing a specific nucleotide sequence;

c) Urine containing 19-androstenedione.

Entry Note 4: Reference materials are sometimes incorporated into specially manufactured equipment.

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

Example 3: A substance with a known triple point in a triple point cell.

Example 4: Glass with known optical density in a transmission filter holder.

Example 5: A uniform sized sphere mounted on a microscope slide.

Entry NOTE 5: Some REFERENCE MATERIALS specify quantities that are metrologically traceable to units of measurement outside the unit system. Such material includes vaccines designated as international units (IU) by the World Health Organization.

Note 6: In a given measurement, a given reference material can only be used for calibration or quality assurance.

Entry Note 7: The specification of the reference material shall include its material traceability, indicating its origin and processing (Accred. Qual. Assur.:2006).

Entry note 8: ISO/REMCO has a similar definition but uses the term “measurement process” to mean “inspection” (ISO 15189:2007, 3.4), which covers the measurement of quantities and the inspection of nominal attributes.

Entry Note 9: Reference materials can be coating thickness standards or gaskets. A portion of the test sample can be used as a work-specific thickness standard if the contract parties agree.

[Source: ISO/IEC Guide 99:2007, 5.13, modified – entry note 9 added.]

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.14 Adjustment

Adjustment of measurement system

A set of operations performed on a measuring system so that it provides a prescribed indication corresponding to a given value to be measured

Note 1: The types of adjustment of the measurement system include zero adjustment, offset adjustment and span adjustment (sometimes called gain adjustment) of the measurement system.

Note 2: Adjustment of a measurement system should not be confused with calibration, which is a prerequisite for adjustment.

Note 3: After the measurement system is adjusted, it is usually necessary to re-calibrate the measurement system.

Note 4: Most digital measuring instruments can be adjusted on a thickness standard or gasket, where the thickness of the coating or gasket is known.

[Source: ISO/IEC Guide 99:2007, 3.11, modified — note 4 added, “adjustment” used as the first preferred term.]

ISO 2808-2019 “Determination of paint film thickness for color and varnishment”

3.15 Accuracy

Accuracy of measurement

The degree of agreement between the measured value and the true quantity value

Remark 1: The concept of “measurement accuracy” is not a quantity and does not give a numerical quantity value. When smaller measurement error is provided, the measurement is said to be more accurate.

Note 2: The term “precision of measurement” should not be used to measure truthfulness and the term “precision of measurement” should not be used to “precision of measurement”, however, this is related to both concepts.

Entry Note 3: “Measurement precision” is sometimes understood to be attributed to the degree of consistent proximity between the measurements being measured.

[Source: ISO/IEC Guide 99:2007, 2.13, modified — “accuracy” is used as a preferred term.]

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