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FINAL
DRAFT

ISO/TC 35/SC 12
Secretariat: BSI
Voting begins on:
2011-11-24
Voting terminates on:
2012-01-24

INTERNATIONAL
STANDARD

ISO/FDIS
8503-3

Preparation of steel substrates before
application of paints and related
products — Surface roughness
characteristics of blast-cleaned steel
substrates —
Part 3:
Method for the calibration of ISO
surface profile comparators and for
the determination of surface profile —
Focusing microscope procedure
Préparation des subjectiles d’acier avant application de peintures et
de produits assimilés — Caractéristiques de rugosité des subjectiles
d’acier décapés —
Partie 3: Méthode d’étalonnage des comparateurs viso-tactiles ISO et
de classification d’un profil de surface — Utilisation d’un microscope
optique

RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR­
TING DOCUMENTATION
...


Please see the administrative notes on page iii

Reference number
ISO/FDIS 8503-3:2011(E)

© ISO 2011

ISO/FDIS 8503-3:2011(E)

Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO
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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
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+ 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso
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iso
...

Violators may be prosecuted
...
The final draft
was established on the basis of comments received during a parallel enquiry on the draft
...

Positive votes shall not be accompanied by comments
...


© ISO 2011 – All rights reserved

iii

ISO/FDIS 8503-3:2011(E)

Contents

Page

Foreword
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vi
1

Scope
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1

3

Terms and definitions
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1

5

Apparatus
...
1
6
...
2
ISO surface profile comparator
...
2

7

Procedure for measurement of maximum peak-to-valley height
...
3

9

Test report
...
5
Annex B (normative) Test report for the calibration of ISO surface profile comparators and for the
determination of surface profiles
...
7
Annex D (informative) Guidance notes for calibrating ISO surface profile comparators using a focusing
microscope
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10
Bibliography
...
The work of preparing International Standards is normally carried out through ISO
technical committees
...
International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work
...

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2
...
Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting
...

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

ISO 8503‑3 was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 12,
Preparation of steel substrates before application of paints and related products
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ISO 8503 consists of the following parts, under the general title Preparation of steel substrates before application
of paints and related products — Surface roughness characteristics of blast-cleaned steel substrates:
— Part 1: Specifications and definitions for ISO surface profile comparators for the assessment of abrasive
blast-cleaned surfaces
— Part 2: Method for the grading of surface profile of abrasive blast-cleaned steel — Comparator procedure
— Part 3: Method for the calibration of ISO surface profile comparators and for the determination of surface
profile — Focusing microscope procedure
— Part 4: Method for the calibration of ISO surface profile comparators and for the determination of surface
profile — Stylus instrument procedure
— Part 5: Replica tape method for the determination of the surface profile

© ISO 2011 – All rights reserved



v

ISO/FDIS 8503-3:2011(E)

Introduction
The performance of protective coatings of paint and related products applied to steel is significantly affected
by the state of the steel surface immediately prior to painting
...

International Standards ISO 8501 (all parts), ISO 8502 (all parts) and ISO 8503 (all parts) have been prepared
to provide methods of assessing these factors, while ISO 8504 (all parts) provides guidance on the preparation
methods which are available for cleaning steel substrates, indicating the capabilities of each in attaining
specified levels of cleanliness
...
Such provisions are
found in other documents, such as national standards and codes of practice
...

The four International Standards referred to above deal with the following aspects of preparation of steel
substrates:
— ISO 8501: Visual assessment of surface cleanliness;
— ISO 8502: Tests for the assessment of surface cleanliness;
— ISO 8503: Surface roughness characteristics of blast-cleaned steel substrates;
— ISO 8504: Surface preparation methods
...

The optical microscope is one of the most widely used instruments for measuring surface profile
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1
...

This method is based on that developed in the USA by the Steel Structures Painting Council
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This method has the disadvantage of requiring a series of tedious measurements, but good precision and
agreement between laboratories and between operators can be obtained by specifying closely the field of view
and depth of field of the microscope
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ISO 8503‑4 describes the procedure using a stylus instrument
...
The many abrasive blast-cleaning procedures
in common use are described in ISO 8504‑2
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This part of ISO 8503 is also applicable to the determination of the surface profile, within the range hy = 20 μm
to 200 μm, of essentially planar blast-cleaned steel
...

NOTE
Where appropriate, this procedure can be used for assessing the roughness profile of other abrasive blastcleaned substrates
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2 Normative references
The following referenced documents are indispensable for the application of this document
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For undated references, the latest edition of the referenced document
(including any amendments) applies
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4 Principle
The test surface is observed over a specified field of view using a specified microscope
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The distance, hy, moved by the objective lens (or the stage) in order to focus on the lowest valley within the
same field of view is determined
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© ISO 2011 – All rights reserved



1

ISO/FDIS 8503-3:2011(E)

5 Apparatus
5
...
5)
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The microscope shall have an objective
lens with a numerical aperture of not less than 0,5 together with an eyepiece lens to give a field of view greater
than 0,5 mm in diameter
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NOTE
Advice concerning the use of the microscope is given in Annexes A and D
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Annex D explains the significance of the defined variables for the microscope (see
the Note to 5
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5
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1) to illuminate the test surface perpendicular to its plane
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NOTE

These requirements for the apparatus (5
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6 Test surfaces
6
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Lightly clean the surface with a dry, fine bristle brush to remove any particles of dust
and then, using a similar brush, wash the surface with petroleum spirit, 40/60 (commercial grade), to remove
oil and grease residues
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Calibrate each segment of the comparator as described in Clause 7
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2 Blast-cleaned steel substrates/replica
Visually check that the surface which is being measured is undamaged
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Allow to dry before carrying out
the procedure
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Determine the surface profile as described in Clause 7
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1 Locate the test surface (see Clause  6) under the objective lens of the microscope (5
...
Adjust the light source (5
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Focus the microscope approximately on the surface
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2 Raise the objective lens until no part of the test area is in focus (see the Notes below); then slowly lower
the objective lens, using the fine adjustment knob, until the first point in the observed area just comes into focus
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NOTE 1 On some microscopes, the objective lens is fixed and the stage is movable
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NOTE 2

lt is considered good practice for focusing to be carried out in the same direction (see D
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7
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2), then, slowly raise
the objective lens until the first point in the observed area just comes into focus
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If the reading cannot be corrected for backlash in the microscope movement, continue
to raise the objective lens until the lowest valley is no longer in focus
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Record the reading, r2, on the vernier scale as the depth of the lowest
valley in that field of view
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4 The difference between the readings (r1 − r2) is the maximum peak-to-valley height, hy, for that field of
view
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5 Repeat the procedure described in 7
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3 and 7
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8 Calculation and expression of results
8
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If the standard deviation obtained is less than one third of the mean, report the standard deviation and the
result as the mean maximum peak-to-valley height, h y
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2 If the method is used to calibrate an ISO surface profile comparator and if the standard deviation obtained
is more than one third of the mean result, repeat the procedure (see Clause  7) and obtain the mean and
standard deviation for the 40 readings
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8
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9 Test report
The form of the test report is given in Annex B and shall contain at least the following information:
a) a reference to this part of ISO 8503, i
...
ISO 8503‑3:2012;
b) all information necessary for the identification of the ISO surface profile comparator and the segments
tested or, if the profile of a steel substrate was determined, the identification of the steel substrate and
whether a replica of the substrate was used;
c) the magnification of the objective lens and its numerical aperture;
d) the magnification of the eyepiece lens and of any intermediate magnification;
e) the diameter of the field of view of the test area;
f)

the total magnification of the microscope;

g) the result of the test as indicated in Clause 8 and, if the profile of an ISO surface profile comparator was
determined, the limits for the comparator (see ISO 8503‑1);
h) any deviations from the procedure specified and, if the profile of a steel substrate was determined on a
replica, the method of preparation of the replica (see Annex E);
i)

the name of the operator;

© ISO 2011 – All rights reserved



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ISO/FDIS 8503-3:2011(E)

j)

any unusual features (anomalies) observed during the test;

k) the date of the test
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1 Carry out the following procedure using the microscope (5
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A
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1) on the stage of the microscope so that the area being
examined is not less than 5 mm from any edge
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Focus approximately the microscope on the surface
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3 Raise the objective lens (see Note 1 to 7
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Slowly lower the
objective lens using the fine adjustment knob, until the first point (i
...
the highest peak) in the observed area just
comes into focus
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Repeat this procedure without moving the comparator until 20 readings have been obtained and then calculate
their mean, p1
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4 Without displacing the comparator, lower the objective lens until the highest peak is no longer in focus
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Record the
reading, p2, of the vernier scale
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A
...
3
...


© ISO 2011 – All rights reserved



5

ISO/FDIS 8503-3:2011(E)

Annex B
(normative)
Test report for the calibration of ISO surface profile comparators and for
the determination of surface profiles

1
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Test surface identification



a) ISO surface profile comparator



b) steel substrate/ replicaa

3
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Microscope details

 



Objective lens magnification

×
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Intermediate

magnificationb

×
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Diameter of field of view


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5
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Any deviations from the International
Standard procedureb

 

7
...


 



9
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Steel

Date of present test(s)
Date(s) of any previous

test(s)b

Name of operator

 
 

a

If profile measurement is of i) a steel substrate or ii) a replica, give details
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c

See separate form (Annex C) for actual readings
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6



© ISO 2011 – All rights reserved

ISO/FDIS 8503-3:2011(E)

Annex C
(normative)
Form for recording surface profile measurements made in accordance
with this part of ISO 8503

Test laboratory and address
Objective lens magnification

×
...
mm

Objective lens numerical aperture

NA
...


 

Intermediate magnification

×
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a) ISO surface profile comparator
b) Steel substrate/replicab

 
Readingc
no
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d

 

If profile measurement is of i) a steel substrate or ii) a replica, give details
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b

 

Replace with “steel substrate” or “replica”, if applicable
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1

Depth of field and field diameter

When using an optical microscope, the choice of lenses available to obtain the magnification required for
observations dictates the depth of field and the maximum field diameter
...
However, the smaller field diameter that results from the use of a high numerical aperture lens
and the consequent higher magnification can fail to contain an adequate representation of high peaks and low
valleys
...

The distribution of the magnification between the objective and eyepiece lenses is important in controlling
the depth of field
...
However, a typical ×10 objective lens has a numerical aperture of 0,26 and gives
a depth of field of about 7 μm
...
The field diameter is in inverse relation to
the total magnification, the latter being obtained by multiplying the magnification of the individual lenses in the
microscope system
...

When these considerations are taken into account, along with the desire to produce a test method for measuring
the surface profiles of ISO comparators, it is necessary that standard requirements be specified in order
to obtain figures aligning with visual and tactile assessments
...
To meet the requirement for an
objective lens with a numerical aperture not less than 0,5 and a field of view greater than 0,5 mm in diameter,
a microscope with an objective lens of ×20, a numerical aperture of 0,5 and an eyepiece lens of ×10 is typical
and provides a total magnification of ×200
...
2

Focus movement

Normal microscopy procedures require the final focusing movement to always be made in the same direction
...
This deviation is permitted in order to increase
substantially the speed of operation because a fine adjustment mechanism, which is free from backlash,
introduces no error when focusing from opposite directions
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5 be used
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Therefore, it is suggested that every effort be made to ensure the
proper movement of the fine adjustment mechanism
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Using this procedure, a
particular instrument can be inspected and the necessary corrections implemented
...
3

Variability of surface profile

To obtain a representative value for the surface profile of abrasive blast-cleaned structural steel, it is necessary
to average at least 20 maximum peak-to-valley heights, hy, obtained by using the procedure described in
Clause  7
...

The standard deviation for a set of 20 peak-to-valley measurements which have been carried out correctly is
usually between 15 % and 25 % of the mean of the measurements
...


© ISO 2011 – All rights reserved



9

ISO/FDIS 8503-3:2011(E)

Annex E
(informative)
Guidance notes for the preparation and measurement of replicas

If the test method is used to verify the profile of a steel substrate, it is usually impractical to obtain a small
sample of the actual surface whose profile is to be determined
...

A replica produces the reverse of the metal surface (that is, the peaks of the steel substrate become the valleys
of the replica and the valleys of the steel become the peaks of the replica), but this reversal does not affect the
validity of the measurement methods described in ISO 8503‑4 and this part of ISO 8503
...
These polymers can have disadvantages in that they do not penetrate
into the deepest, sharpest valleys and that a release agent can be required
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A two-component pigmented silicone rubber product has also been used with success
...
Because of its softness, however, measurement is restricted to the microscope method
described in this part of ISO 8503
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These steel surfaces should have been prepared by
use of abrasive of the same type as that used on the surface being tested, and they should have profiles which
span the test surface profile range
...

If a replicating technique is used to determine the surface profile of a substrate, this should be stated when
reporting the mean maximum peak-to-valley height
...
220

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