IEC/TS 60695-6-31:2013 describes the test methods for the determination of the specific optical density of smoke produced by materials used in electrotechnical products using the apparatus described in technical specification IEC/TS 60695-6-30. Test specimens are exposed vertically to a radiant heat source with or without the application of a pilot flame in a closed chamber (i.e. without air-change). The test methods are only applicable to flat, solid, non-metallic test specimens of materials used in electrotechnical products. This technical specification does not provide a classification system for the behaviour of materials. The test methods are not applicable to materials which melt and flow away from the direct impingement of heat flux. The test methods are not recommended for further development for electrotechnical products, nor are they recommended as the basis for regulation or other controls on smoke release due to the limitations of the physical fire model and the test specimen geometry - see Clause 4. This second edition cancels and replaces the first edition published in 1999. It constitutes a technical revision. The main changes with respect to the previous edition are:
- the Foreword has been revised and updated,
- the Introduction has been updated,
- the Scope has been updated
- the Normative references have been updated,
- minor technical changes have been made throughout the document, and
- detailed editorial updates have been added throughout the document. It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC Guide 51. Keywords: Fire Hazard testing, Smoke obscuration.

This publication is to be read in conjunction withIEC 60695-6-30:1996.