ISO 3231-1993 PDF

Full title and description

ISO 3231:1993 — Paints and varnishes — Determination of resistance to humid atmospheres containing sulfur dioxide. This International Standard specifies a laboratory test method in which coated test panels are exposed to controlled humid atmospheres containing sulfur dioxide to assess the resistance of single-coat films or multi-coat systems of paints and related products. The 1993 edition has been withdrawn and a newer method/series (ISO 22479:2019 and related documents) supersedes it.

Abstract

The procedure exposes coated panels to specified humid atmospheres containing sulfur dioxide and evaluates the effects of exposure by criteria agreed between the parties. A volume of 0.2 litre of sulfur dioxide (measured at atmospheric pressure) is generally recommended for testing coatings with film thicknesses up to about 40 μm. The test applies to single-coat films and multi‑coat systems; assessment criteria are normally agreed in advance and are often subjective (visual evaluation, blistering, color change, loss of adhesion, etc.).

General information

• Status: Withdrawn (superseded).
• Publication date: January 1993 (1993-01).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 87.040 — Paints and varnishes.
• Edition / version: Edition 2 (1993).
• Number of pages: 5 pages.

Key bibliographic and lifecycle details above are taken from ISO bibliographic records and national standards bodies which show the 1993 second edition (5 pages) and indicate withdrawal and replacement by ISO 22479:2019.

Scope

Applies to the determination of the resistance of paint and varnish films (single or multi-coat systems) to humid atmospheres containing sulfur dioxide. The method is intended for laboratory comparison and qualification testing rather than direct prediction of in-service lifetime; exposure conditions, SO2 dose and evaluation criteria should be agreed between the contracting parties before testing. The 1993 method targets coatings up to about 40 μm thickness with a recommended SO2 charge of 0.2 litre (atmospheric pressure) as a typical test parameter.

Key topics and requirements

• Test principle: controlled exposure of coated panels to humidified atmospheres containing a defined quantity of sulfur dioxide.
• Typical SO2 dose: 0.2 litre (measured at atmospheric pressure) recommended for coatings ≤ ~40 μm.
• Sample preparation: specified panel types and film thickness control to ensure repeatability.
• Exposure control: humidity, temperature and SO2 dosing must be controlled and recorded.
• Evaluation: effects assessed by pre‑agreed criteria (visual assessment, blistering, discoloration, adhesion loss); often subjective and requiring specification in test contract.
• Limitations: laboratory simulation — results depend strongly on agreed exposure parameters and evaluation criteria; not a direct in-service life prediction without correlation work.

Summary of technical requirements is based on the ISO 3231:1993 procedure description and subsequent recommendations reflected in newer standards addressing SO2 fixed‑gas methods.

Typical use and users

Used by coatings manufacturers, independent testing laboratories, quality assurance teams, specification writers and research groups for comparative testing and qualification of paint and varnish systems against sulfur dioxide humid‑atmosphere exposure. It is used when stakeholders need a repeatable laboratory method to compare formulation resistance or to validate protective systems under controlled corrosive humidity conditions.

Related standards

ISO 3231:1993 has been withdrawn and superseded by later methods addressing sulfur dioxide fixed‑gas tests and broader material applicability (notably ISO 22479:2019). Other related standards commonly referenced in testing programmes include standards for panel preparation and film thickness (for example ISO 1514 and ISO 2808) and corrosion terminology/assessment standards used in conjunction with SO2 exposure methods.

Keywords

ISO 3231, paints and varnishes, sulfur dioxide, SO2, humid atmosphere, exposure test, corrosion test, coatings resistance, film thickness, laboratory method.

FAQ

Q: What is this standard?

A: ISO 3231:1993 is an ISO laboratory test method titled "Paints and varnishes — Determination of resistance to humid atmospheres containing sulfur dioxide" that prescribes exposure of coated panels to humid SO2-containing atmospheres to assess coating resistance.

Q: What does it cover?

A: It covers the exposure procedure, suggested SO2 dose (commonly 0.2 litre at atmospheric pressure for thin films), sample preparation basics, and evaluation by agreed criteria for single‑coat or multi‑coat paint systems. The evaluation criteria are typically agreed between parties and often rely on visual/qualitative assessment.

Q: Who typically uses it?

A: Coatings manufacturers, independent testing laboratories, QA departments, specifiers and research organizations use the method for comparative testing, product development and conformance checks.

Q: Is it current or superseded?

A: ISO 3231:1993 has been withdrawn and is superseded by later standards addressing sulfur dioxide testing (notably ISO 22479:2019 and related national/adopted versions). Users should refer to ISO 22479:2019 (and applicable regional/adopted standards) for the current method and wider applicability.

Q: Is it part of a series?

A: Yes — it forms part of the family of ISO standards and test methods dealing with paints, varnishes and related products and their exposure/corrosion testing; it sits in the scope of ISO/TC 156 (paints and related products) and is connected to broader corrosion and coating test standards.

Q: What are the key keywords?

A: Paints and varnishes; sulfur dioxide; SO2; humid atmosphere; coatings resistance; exposure test; corrosion testing; ISO 3231; ISO 22479.