ISO 18768-2:2022

INTERNATIONAL ISO
STANDARD 18768-2
First edition
2022-06
Organic coatings on aluminium and
its alloys — Methods for specifying
decorative and protective organic
coatings on aluminium —
Part 2:
Liquid coatings
Couches organiques sur l’aluminium et ses alliages — Méthodes
de spécification des revêtements décoratifs et protecteurs sur
aluminium —
Partie 2: Revêtements liquides
Reference number
© ISO 2022
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Published in Switzerland
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Contents Page
Foreword . vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Information to be supplied by the customer to the surface processor .3
5 Metal preparation and pretreatment . 5
5.1 Material (substrate) . 5
5.2 Pretreatment of the substrate . 5
5.2.1 General . 5
5.2.2 Degreasing etching and rinsing . 5
5.2.3 Anodic oxidation coating . 5
5.2.4 Chemical conversion coatings . 5
5.2.5 Alternative pretreatment . 6
6 Categories . 6
7 Tests . 8
7.1 General . 8
7.2 Appearance . 8
7.2.1 General . 8
7.2.2 Measurement . 8
7.2.3 Requirement . 8
7.3 Colour . 9
7.3.1 General . 9
7.3.2 Visual method . 9
7.3.3 Instrumental method . 9
7.4 Gloss . 9
7.4.1 Measurement . 9
7.4.2 Requirement . 10
7.5 Brightness (distinctness of image) . 10
7.5.1 General . 10
7.5.2 Measurement . 10
7.5.3 Requirement . 10
7.6 Thickness . 10
7.6.1 General . 10
7.6.2 Measurement . 11
7.6.3 Requirement . 11
7.7 Hardness (pencil) . . 11
7.7.1 Measurement . 11
7.7.2 Requirement . 11
7.8 Adhesion . 11
7.8.1 General . 11
7.8.2 Scratch circular roll method .12
7.8.3 Dry adhesion test .12
7.8.4 Wet adhesion test.13
7.8.5 Pull-off test .13
7.9 Impact resistance . 13
7.9.1 General .13
7.9.2 Measurement . 14
7.9.3 Requirement . 14
7.10 Multi-impact stone chipping resistance . 14
7.10.1 General . 14
7.10.2 Measurement . 14
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7.10.3 Requirement . 14
7.11 Abrasion resistance . . . 14
7.11.1 General . 14
7.11.2 Falling sand test . 14
7.11.3 Rotating, abrasive rubber-wheel test . 15
7.11.4 Friction coefficient . 15
7.12 Cupping test.15
7.12.1 Measurement .15
7.12.2 Requirement .15
7.13 Flexibility. 16
7.13.1 General . 16
7.13.2 T-bend test . 16
7.13.3 Cylindrical mandrel bend test . 17
7.14 Processing resistance . 17
7.14.1 Measurement . 17
7.14.2 Requirement . 17
7.15 Permeating depths of ink . 17
7.15.1 Measurement .
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