ISO 696-1975 PDF

Full title and description

Surface active agents — Measurement of foaming power — Modified Ross‑Miles method. This International Standard specifies a laboratory procedure (the modified Ross‑Miles method) for measuring the foaming power of surface‑active agents by measuring the volume of foam produced when a defined volume of test solution is poured from a fixed height onto the surface of the same solution under controlled conditions.

Abstract

This standard describes a quantitative test for foaming power: 500 ml of the test solution is discharged from a height of 450 mm onto the surface of the same solution and the volume of foam produced and its decay over the following minutes are measured. The method is applicable to most surface‑active agents but is not reliable for easily hydrolysable substances or very dilute environmental samples; results for formulated products must be interpreted with caution.

General information

• Status: Published (International Standard).
• Publication date: July 1975 (ISO 696:1975, First edition).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 71.100.40 (Surface‑active agents / surfactants).
• Edition / version: Edition 1 (1975).
• Number of pages: 5 pages.

Scope

Specifies a laboratory method for measuring the foaming power of surface‑active agents by the modified Ross‑Miles technique. The test determines foam volume formed immediately after dispensing and monitors foam decay (notably over the first five minutes). The standard applies to most surfactants under controlled laboratory conditions but excludes reliable measurement of readily hydrolysable agents and very dilute environmental samples; it also cautions that precisely defined laboratory conditions may not reflect product behaviour in practical use.

Key topics and requirements

• Test principle: discharge 500 ml of test solution from 450 mm onto the same solution surface and measure foam volume and its persistence (decay over time).
• Test solution preparation: prepare from laboratory sample at working strength; water used may be distilled (air‑saturated) or hard water with defined calcium hardness as specified.
• Apparatus: separating funnel (1 L) with specified outlet geometry, measuring cylinders (1 L and 500 ml), graduated 50 ml pipette or cylinder, metering tube specifications, stand and thermostat water bath for temperature control.
• Limitations and sensitivity: results sensitive to insoluble particles, small compositional changes and hydrolysis products; low‑foaming or very dilute solutions may give results of limited practical relevance.
• Reporting: measured foam volumes and observations on foam decay/persistence, test conditions (temperature, water hardness, concentration) and any deviations from the specified apparatus or procedure must be recorded.

Typical use and users

Used in laboratories for quality control, R&D and comparative testing by manufacturers of detergents, cleaners, personal‑care products and other surfactant‑based formulations; also used by test laboratories, raw‑material suppliers and regulatory or standards organisations to characterise foaming behaviour under standardised conditions. Results are primarily comparative and for specification/quality purposes rather than direct prediction of in‑use performance.

Related standards

Related ISO documents and references frequently cited in conjunction with ISO 696: ISO 607 (sample division for surface active agents), ISO/R 862 (glossary of terms for surface active agents), ISO 2174 (preparation of water with known calcium hardness) and later/related standards and technical reports that update vocabulary or sizing of surfactant test methods. Users should consult current ISO catalogues for newer or superseding documents.

Keywords

surface active agents, surfactants, foaming power, Ross‑Miles method, foam volume, foam persistence, detergent testing, laboratory method, ISO 696:1975.

FAQ

Q: What is this standard?

A: ISO 696:1975 is an International Standard that specifies the modified Ross‑Miles laboratory method for measuring the foaming power of surface‑active agents.

Q: What does it cover?

A: It covers the test principle, required apparatus, test solution preparation, procedural steps (including discharging 500 ml from 450 mm), measurement of foam volume and notes on interpretation and limitations (e.g., sensitivity to hydrolysis and insoluble matter).

Q: Who typically uses it?

A: Chemical and consumer‑product manufacturers, QC and R&D laboratories, raw‑material suppliers and testing/standards organisations that need a standardised comparative measure of foaming behaviour.

Q: Is it current or superseded?

A: ISO 696 was published in July 1975 (first edition). Users should verify current status via the ISO catalogue because standards may be confirmed, revised or withdrawn over time; the ISO catalogue entry is the authoritative source for current lifecycle status.

Q: Is it part of a series?

A: It is part of the body of ISO work on surface‑active agents (work of ISO/TC 91) and is associated with other methods, vocabularies and preparative standards referenced in its text (for example sample division, water preparation and glossary standards). Consult ISO/TC 91 documents for the broader series.

Q: What are the key keywords?

A: surfactant, foaming power, Ross‑Miles, foam volume, foam persistence, detergent testing, ISO 696.