SIST EN ISO 2808:2007

SLOVENSKI OSIST prEN ISO 2808:2004

PREDSTANDARD
december 2004
Paints and varnishes - Determination of film thickness (ISO/DIS 2808:2004)
ICS 87.040 Referenčna številka
OSIST prEN ISO 2808:2004(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
DRAFT
prEN ISO 2808
NORME EUROPÉENNE

EUROPÄISCHE NORM

October 2004
ICS Will supersede EN ISO 2808:1999
English version
Paints and varnishes - Determination of film thickness (ISO/DIS
2808:2004)
Peintures et vernis - Détermination de l'épaisseur du feuil
(ISO/DIS 2808:2004)
This draft European Standard is submitted to CEN members for parallel enquiry. It has been drawn up by the Technical Committee
CEN/TC 139.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 2808:2004: E
worldwide for CEN national Members.

---------------------- Page: 2 ----------------------
prEN ISO 2808:2004 (E)


Foreword

This document (prEN ISO 2808:2004) has been prepared by Technical Committee ISO/TC 156
"Corrosion of metals and alloys" in collaboration with Technical Committee CEN/TC 139 "Paints
and varnishes", the secretariat of which is held by DIN.

This document is currently submitted to the parallel Enquiry.

This document will supersede EN ISO 2808:1999.


Endorsement notice

The text of ISO 2808:2004 has been approved by CEN as prEN ISO 2808:2004 without any
modifications.
2

---------------------- Page: 3 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 2808
ISO/TC 35/SC 9 Secretariat: BSI
Voting begins on: Voting terminates on:
2004-10-28 2005-03-28
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Paints and varnishes — Determination of film thickness
Peintures et vernis — Détermination de l'épaisseur du feuil
[Revision of third edition (ISO 2808:1997)]
ICS 87.040

ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a subject
of interest to European standardization. In accordance with the ISO-lead mode of collaboration as
defined in the Vienna Agreement, consultation on this ISO/DIS has the same effect for CEN
members as would a CEN enquiry on a draft European Standard. Should this draft be accepted, a
final draft, established on the basis of comments received, will be submitted to a parallel two-month FDIS
vote in ISO and formal vote in CEN.
In accordance with the provisions of Council Resolution 15/1993 this document is circulated in
the English language only.
Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué
en version anglaise seulement.
To expedite distribution, this document is circulated as received from the committee secretariat.
ISO Central Secretariat work of editing and text composition will be undertaken at publication
stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
© International Organization for Standardization, 2004

---------------------- Page: 4 ----------------------
ISO/DIS 2808
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the
unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user's country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, photocopying,
recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO's
member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
©
ii ISO 2004 – All rights reserved

---------------------- Page: 5 ----------------------
ISO/DIS 2808
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Determination of wet-film thickness . 3
4.1 General. 3
4.2 Mechanical determination. 3
4.3 Gravimetric determination . 7
4.4 Photothermal determination . 8
5 Determination of dry-film thickness . 9
5.1 General. 9
5.2 Mechanical determination. 9
5.3 Gravimetric determination . 15
5.4 Optical determination. 16
5.5 Magnetic determination. 19
5.6 Radiological determination . 22
5.7 Photothermal determination . 23
5.8 Acoustic determination . 25
6 Determination of thickness of uncured coating powder film. 26
6.1 General. 26
6.2 Gravimetric determination . 26
6.3 Magnetic determination. 27
6.4 Photothermal determination . 29
7 Measurement of film thickness on rough surfaces. 30
7.1 General. 30
7.2 Apparatus and materials . 30
7.3 Procedure. 31
8 Test report. 31
Annex A (informative) Overview of methods. 33

© ISO 2004 – All rights reserved iii

---------------------- Page: 6 ----------------------
ISO/DIS 2808
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 2808 was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9.
This fourth edition cancels and replaces the third edition (ISO 2808:1997), which has been technically revised.
The main changes are as follows:
a) The structure of the standard was changed into four main clauses:
1) Determination of wet-film thickness;
2) Determination of dry film thickness;
3) Determination of thickness of uncured coating powder film; and
4) Determination on rough surfaces.
b) The photothermal principle, radiological principle and acoustic principle were added.
c) The split-beam method has been deleted as such instruments are no longer manufactured.
iv © ISO 2004 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/DIS 2808
Introduction
Measurement of film thickness consists of the following steps:
a) calibration, typically performed by the manufacturer or by any qualified laboratory;
b) verification, an accuracy check performed by the user;
c) adjustment, aligning the gage's thickness readings to match those of a known sample. For a dry film
thickness gage this would mean adjustment to Zero on the uncoated surface or to known film thickness
such as shims;
d) measurement.
© ISO 2004 – All rights reserved v

---------------------- Page: 8 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 2808

Paints and varnishes — Determination of film thickness
1 Scope
This International Standard specifies a number of methods that are applicable to the measurement of
thickness of coatings applied to a substrate. Methods for determining wet-film thickness, dry-film thickness
and film thickness of uncured coating powder films are described.
This International Standard also defines terms concerning the determination of film thickness.
An overview on the methods is given in Annex A. The field of application (characterisation), existing standards
and the precision are specified for the individual methods. Where test standards exist for the individual
methods, reference is made to these. Otherwise the method is described in detail.
This International Standard does not deal with measurement on blasted rough surfaces and acceptance
criteria. Evaluation of measurements is dealt with in ISO 19840.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 463, Geometrical Product Specification (GPS) — Dimensional measuring equipment — Design and
metrological characteristics of mechanical dial gauges (Revision of ISO/R 463:1965).
ISO 1101, Technical drawings — Geometrical tolerancing — Tolerancing of form, orientation, location and
run-out — Generalities, definitions, symbols, indications on drawings.
ISO 2178, Non-metallic coatings on magnetic substrates — Measurement of coating thickness — Magnetic
method.
ISO 2360, Non-conductive coatings on non-magnetic basic metals — Measurement of coating thickness —
Eddy current method.
ISO 3543, Metallic and non-metallic coatings — Measurement of thickness — Beta backscanner method.
ISO 3611, Micrometer callipers for external measurement.
ISO 4287, Geometrical Product Specification (GPS) — Surface texture: Profile method —Terms, definitions
and surface texture parameters.
1)
, Paints and varnishes — Terms and definitions for coating materials — Part 1: General terms.
ISO 4618

1)
Under revision.
© ISO 2004 – All rights reserved 1

---------------------- Page: 9 ----------------------
ISO/DIS 2808
ISO 8501-1, Preparation of steel substrates before application of paints and related products — Visual
assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel
substrates and of steel substrates after overall removal of previous coatings.
DIN 863, Verification of geometrical parameters — Micrometers — Part 2: Micrometer callipers heads, Depth
micrometer; concepts, requirements, testing.
DIN 50992-2, Thickness measurement of coatings and characterisation of surfaces with surface waves —
Part 2: Thickness measurement of coatings by photometric method.
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 4618 and the following
apply
3.1
substrate
surface to which a coating material is applied or is to be applied [ISO 4618]
3.2
coating
continuous layer formed from a single or multiple application of coating material to a substrate [ISO 4618]
3.3
film thickness
distance between the surface of the film and the surface of the substrate
3.4
wet-film thickness
the thickness of a freshly applied wet coating material, measured immediately after application
3.5
2)
dry-film thickness
thickness of a coating remaining over the peaks of a rough surface when the coating has hardened
3.6
thickness of uncured coating powder film
the thickness of a freshly applied coating material in powder form, measured immediately after application and
before stoving
3.7
2)
significant surface area
that part of an article covered or to be covered by the coating and for which the coating is essential for
serviceability and/or appearance
3.8
2)
reference area
that part of the significant surface area within which an agreed number of single measurements is made
(spot-check which is representative for the film thickness of the relevant layer)
3.9
2)
measurement area
the area over which a single measurement is made

2)
This term is only required for the extended evaluation of the film thickness measurements; see test report j) and k).
2 © ISO 2004 – All rights reserved

---------------------- Page: 10 ----------------------
ISO/DIS 2808
3.10
2)
minimum local film thickness
the lowest value of the local film thickness found on the significant surface area of a particular article
3.11
2)
maximum local film thickness
highest acceptable dry film thickness above which the performance of the paint or the paint system may be
impaired
3.12
2)
mean film thickness
arithmetic mean of all the individual dry film thicknesses in the inspection area
3.13
calibration
the controlled and documented process of measuring traceable calibration standards and verifying that the
results are within the stated accuracy of the gage
NOTE Calibrations are typically performed by the gage manufacturer or by a qualified laboratory in a controlled
environment using a documented process. The standards used in the calibration are such that the combined uncertainties
of the resultant measurement are less than the stated accuracy of the gage.
3.14
verification
an accuracy check performed by the user using known reference standards
3.15
reference standard
a sample of known thickness against which a user may verify the accuracy of the gage
NOTE Reference standards may be coated thickness standards, or shims. If agreed to by the contracting parties, a
sample part may be used as a thickness standard for a particular job.
3.16
adjustment
the act of aligning the gage's thickness readings to match those of a known sample in order to improve the
accuracy of the gage on a specific surface or in a specific portion of its measurement range
NOTE Most electronic gages can be adjusted on a coated part or on a shim, where the thickness of the coating or of
the shim is known.
3.17
accuracy
consistency between a measured value and the true value of the thickness standard
4 Determination of wet-film thickness
4.1 General
Annex A gives an overview of the methods used for the determination of wet-film thickness.
4.2 Mechanical determination
4.2.1 Principle
In all mechanical methods the substrate surface is touched through the coating and the surface of the coating
is touched simultaneously (method 1A) or subsequently (methods 1B and 1C). The wet-film thickness is the
difference between these contacts which can be read directly.
© ISO 2004 – All rights reserved 3

---------------------- Page: 11 ----------------------
ISO/DIS 2808
4.2.2 Field of application
The mechanical principle is suitable for all film-substrate combinations. The substrate should be flat in the
area where the measurement is conducted. Curvature of the surface in a single plane is permissible (e.g.
internal or external surface of pipes).
4.2.3 General
Classification as a destructive or non-destructive method depends on:
 the rheological properties of the coating material
 wetting contact between the test surfaces of the measuring instrument and the coating material
 the later application for which the coating is used.
Since the possibility of pigment particles remaining between the stylus and the substrate cannot be excluded,
all mechanical methods contain a systematic error: the film thickness displayed is smaller than the actual wet-
film thickness by at least the mean thickness of the pigment particles.
Wetting of the wheel gauge is a further systematic error which applies only to method 1B. It can result in
exaggerated readings and is a function of:
 the surface tension and the rheological properties of the coating material;
 the material of the wheel gauge;
 the rate of revolution of the wheel.
4.2.4 Method 1A — Comb gauge
4.2.4.1 Apparatus
Flat disc made of a corrosion-resistant material with teeth incorporated in its edge. The reference teeth at the
corners of the disc define a baseline from which the inner teeth are arranged in a graduated series of gaps.
Each tooth is labelled with the assigned gap value (see Figure 1).
With commercially available comb gauges the maximum measurement range is 2000 µm and the smallest
increment is 5 µm.
Key
1 Substrate
2 Coating
3 Wetting contact
4 Comb gauge

Figure 1 — Comb gauge
4 © ISO 2004 – All rights reserved

---------------------- Page: 12 ----------------------
ISO/DIS 2808
4.2.4.2 Procedure
Ensure that the teeth are clean and not worn or damaged. Place the comb gauge onto the flat specimen
surface such that the teeth are normal to the plane of the surface. Allow sufficient time for the coating to wet
the teeth prior to removing the gauge.
In the case of specimens curved in a single plane the comb gauge shall be placed in position parallel to the
axis of curvature.
Take the reading as soon as possible after application.
Note the greatest gap reading of the tooth wetted by the coating material as the wet-film thickness.
4.2.5 Method 1B — Wheel gauge
4.2.5.1 Apparatus
Wheel, made of hardened and corrosion-resistant steel, with three projecting rims:
Two rims are ground to the same diameter and are configured concentrically to the rotating wheel axle which
protrudes at both sides. The third rim has a smaller diameter and is eccentrically ground. One of the outer
rims has a scale from which the respective projection of the concentric rims relative to the eccentric rim can be
read (see Figure 2).
Two versions are available:
 version 1 has the eccentric rim configured between the concentric rims;
 version 2 has the eccentric rim configured outside the concentric rims and closely adjacent to one of them.
NOTE Unlike version 1, the design of version 2 enables parallax-free reading of the wet-film thickness.
With commercially available wheel gauges the maximum measurement range is 1500 µm and the smallest
increment is 2 µm.
Key
1 Substrate
2 Coating
3 Eccentric rim
4 Wheel gauge

Figure 2 — Wheel gauge
4.2.5.2 Procedure
Grip the wheel gauge with the thumb and index finger by the rotating axle and press the concentric rims onto
the surface at the point of the largest reading on the scale.
© ISO 2004 – All rights reserved 5

---------------------- Page: 13 ----------------------
ISO/DIS 2808
In the case of specimens curved in a single plane the axis of curvature and the wheel gauge axle shall be
parallel.
Roll the wheel gauge in one direction, lift from the surface and read off the highest scale reading at which the
eccentric rim is still wetted by the coating material. Clean the gauge and repeat in the other direction.
Take the reading as soon as possible after application.
Calculate the wet-film thickness as the arithmetic mean of these readings.
NOTE To minimize the effect of the surface tension on the result, observe how the paint wets the eccentric rim and
record the scale reading the first point of contact. This is only possible with version 2 of the wheel gauge.
4.2.6 Method 1C — Dial gauge
4.2.6.1 Apparatus and materials
4.2.6.1.1 Dial gauge
Dial gauge conforming to the requirements of ISO 463, or electronic dial gauge capable of measuring to an
accuracy of at least 5 µm or 1 µm, respectively. The dial gauge can have a scale display or a numerical
display (see Figure 3).
The underside of the dial gauge contains two contact pins of equal length located equidistantly from the
movable measurement tip and in a straight line with it. An adjusting screw is be used to move the
measurement tip sensitively in its guideway.
Key
1 Substrate
2 Coating
3 Measurement tip

Figure 3 — Surface profile gauge
4.2.6.1.2 Reference standards for calibration
Flat reference plate for calibrating the zero point of the dial gauge. The calibration plate consists of flat glass
whose flatness tolerance may not exceed 1 µm (see ISO 1101).
4.2.6.2 Procedure
Calibrate the dial gauge by checking the zero point on the calibration plate with the measurement tip foot
adjusted so that it is just touching the plate.
Screw the measurement tip back from the calibration position. Place the contact pins of the dial gauge on the
specimen such that they are normal to the plane of the surface and carefully screw the measurement tip in
until the stylus tip is just touching the coating material.
6 © ISO 2004 – All rights reserved

---------------------- Page: 14 ----------------------
ISO/DIS 2808
Take the reading as soon as possible after application.
Read the wet-film thickness directly from the gauge, after correcting the zero-shift if necessary.
4.3 Gravimetric determination
4.3.1 Principle
A coating is applied and the thickness is determined by dividing the mass of the coating by its density.
The wet-film thickness, t , in micrometers is calculated from the equation
w
m−m
0
t= (1)
w
A⋅ρ
where
m  is the mass of the uncoated specimen, in grams;
0
m  is the mass of the coated specimen, in grams;
A is the coated surface area, in square metres;
ρ is the density of the liquid coating material applied, in grams per millilitre.
NOTE The density of the liquid coating material applied can be determined in accordance with ISO 2811-1,
ISO 2811-2, ISO 2811-4 or ISO 2811-4 .
4.3.2 Field of application
The gravimetric principle is generally applicable provided that the amount of highly volatile substances in the
liquid coating material is low.
4.3.3 General
Testing using the gravimetric principle yields the mean value of the wet-film thickness over the entire coated
surface area. With spray application in particular, the reverse side of the specimen shall be masked to prevent
measurement errors resulting from partial coating of the reverse (overspray). Any masking of the reverse side
shall be removed before weighing the coated specimen.
4.3.4 Method 2 — Gravimetric difference
4.3.4.1 Apparatus
Scales, capable of weighing up to 500 g to the nearest 1 mg.
4.3.4.2 Procedure
Weigh the uncoated and coated specimens one after the other and calculate the wet-film thickness using
equation (1).
© ISO 2004 – All rights reserved 7

---------------------- Page: 15 ----------------------
ISO/DIS 2808
4.4 Photothermal determination
4.4.1 Principle
The film thickness is determined from the time difference between a thermal wave radiated into the coating
material and the subsequent heat propagation, e.g. a reflected wave (see Figure 4).
Irrespective of the excitation type or detection method, all the photothermal test methods share the targeted
periodic or pulsed introduction of energy in heat form into a specimen and the subsequent detection of the
local temperature increase generated.
The film thickness is derived from the detected signal on the basis of the calibration as in 4.4.4.2 where
excitation parameters are fixed (excitation energy, pulse duration, excitation frequency, etc.).
Key
1 Substrate
2 Coating
3 Thermal radiation
4 Volume absorption
5 Optical radiation source
6 Thermal waves
7 Sound waves
8 Surface deformation

Figure 4 — Interaction of radiation with the specimen as the basis of photothermal materials testing, with
surface deformation

4.4.2 Field of application
The photothermal principle is fundamentally suitable for all film-substrate combinations provided the individual
films are sufficiently distinguishable with reference to their heat conductivity and reflection properties.
The required minimum substrate thickness is a function of the measurement system used (see 4.4.4.1.1) and
the respective film-substrate combination.
4.4.3 General
Classification of a method as destructive or non-destructive depends on the purpose of the coating. The
radiated wave could have an impact on the coating material because of local heat action (see no. 7 in Figure
4).
8
...