ISO 8078:2025

International
Standard
ISO 8078
Second edition
Aerospace process — Anodic
2025-05
treatment of aluminium alloys —
Sulfuric acid process, undyed coating
Procédés de traitement dans l'industrie aérospatiale —
Traitement anodique des alliages d'aluminium — Traitement à
l'acide sulfurique pour revêtement non teinté
Reference number
© ISO 2025
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Technical requirements . 2
4.1 Materials to be anodized .2
4.2 Process requirements .2
4.3 Process details .2
4.3.1 General rules .2
4.3.2 Water quality .2
4.3.3 Racking of parts .2
4.3.4 Cleaning requirement .3
4.3.5 Deoxidizing . .3
4.3.6 Anodizing procedure .3
4.3.7 Sealing.3
4.3.8 Drying .3
4.3.9 Rework .4
4.3.10 Temperature control .4
5 Quality assurance provisions . . 4
5.1 Responsibility for inspection.4
5.2 Lot acceptance tests.4
5.3 Process control tests .4
5.4 Process qualification tests .4
5.5 Solution control . .5
5.5.1 Surface preparation and anodizing baths . .5
5.5.2 Sealing bath.5
5.6 Inspection and testing of coatings .5
5.6.1 Visual examination .5
5.6.2 Coating mass per unit area.5
5.6.3 Thickness of coating .5
5.6.4 Corrosion resistance .6
5.6.5 Effectiveness of sealing .6
5.7 Approval .6
6 Packaging and delivery . 6
6.1 Packaging .6
6.2 Delivery .6
Bibliography . 8

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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
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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).
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This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 18, Materials.
This second edition cancels and replaces the first edition (ISO 8078:1984), which has been technically
revised.
The main changes are as follows:
— updated the normative references in Clause 2;
— changed water quality requirements, for example, the total dissolved solids has been changed from
12 mg/kg to 10 mg/kg (see 4.3.2);
— added a hexavalent chromium free sealing solution (see 4.3.7);
— added drying and rework (see 4.3.8 and 4.3.9);
— made the requirements of process control tests and process qualification tests clearer (see 5.3 and 5.4).
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.

iv
International Standard ISO 8078:2025(en)
Aerospace process — Anodic treatment of aluminium alloys
— Sulfuric acid process, undyed coating
1 Scope
This document specifies requirements for producing and testing an undyed sulfuric acid anodic coating on
aluminium alloys.
The anodizing process is applied in the manufacture of aerospace products to improve paint adhesion and
resistance to corrosion.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 2064, Metallic and other inorganic coatings — Definitions and conventions concerning the measurement of
thickness
ISO 2106, Anodizing of aluminium and its alloys — Determination of mass per unit area (surface density) of
anodic oxidation coatings — Gravimetric method
ISO 2360, Non-conductive coatings on non-magnetic electrically conductive base metals — Measurement of
coating thickness — Amplitude-sensitive eddy-current method
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by acceptance
quality (AQL) for lot-by-lot inspection
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1
lot
all parts treated in the same baths at the same time
[SOURCE: ISO 8081:2021, 3.1]
3.2
water-break-free surface
surface that maintains a continuous water film for a period of at least 30 s after being sprayed or rinsed by
immersion in clean water at ambient temperature
[SOURCE: ISO 8081:2021, 3.2]
4 Technical requirements
4.1 Materials to be anodized
The alloys shall be of a chemical composition compatible with sulfuric acid anodizing.
The base metal shall be free from surface defects caused by metalworking processes or handling, and free
from grease, pitting, corrosion, heavy etching, etc. which are detrimental to the application of anodized
coatings capable of meeting the requirements of this document.
4.2 Process requirements
The processes employed shall be suc
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