What is ISO 18936 about ?
ISO 18936 describes test methods for determining the long-term dark storage stability of colour photographic images.
Note1: ISO 18936 is applicable to colour photographic images made with traditional photographic materials. These images are generated with systems such as chromogenic, silver dye-bleach, dye transfer, dye-diffusion transfer “instant”, and similar systems.
Note2: The test method specified in ISO 18936 also covers the dark-stability of digital colour images produced with dry- and liquid-toner electrophotography, thermal dye transfer (sometimes called “dye sublimation”), and inkjet printing systems.
Who is ISO 18936 for ?
ISO 18936 on methods for measuring thermal stability is useful for:
- Photographers
- Thermal stability testers
- Museum’s caretakers
Why should you use ISO 18936 ?
Today, the majority of photographs are made with colour dyes and pigments. The length of time that such photographs are to be kept can vary from a few days to many hundreds of years, and the importance of image stability can be correspondingly small or great. Often the ultimate use of a particular photograph may not be known at the outset. Knowledge of the useful life of colour photographs is important to many users, especially since stability requirements often vary depending upon the application. For museums, archives and others responsible for the care of colour photographic materials, an understanding of the behaviour of these materials under various storage and display conditions is essential if they are to be preserved in good condition for long periods of time.
Long-term changes in image density, colour balance and stain level can be reasonably estimated only when a good correlation has been confirmed between accelerated tests and actual conditions of use. Density changes induced by the test conditions and measured during and after incubations include those in the support and in the various auxiliary layers that may be in a particular product. With most materials, however, the major changes occur in the image-bearing layer. In general, photographic materials tend to undergo dramatic changes above 60 % RH (especially at the high temperatures used in accelerated tests) owing to changes in the physical properties of gelatine and other binder materials. Lower maximum relative humidity may need to be tested for some of the more humidity-sensitive inkjet materials because of phase changes such as melting point or glass transition temperature.
ISO 18936 covers the methods and procedures for measuring the long-term, dark storage stability (thermal stability) of colour photographs.
What’s changed since the last update ?
BS ISO 18936:2020 supersedes BS ISO 18936:2012, which is withdrawn.
BS ISO 18936:2020 replaces BS ISO 18936:2012, which has been technically revised. The main changes compared to the previous edition are as follows:
- The test methods for environmental stress factors have been changed to align with ISO 18944
- The calculations and computations section has been removed as they are now contained in ISO 18944
- Annex A has been removed as the method for interpolation is now contained in ISO 18944:2018, Annex B
- The usage and reporting requirements have been updated to ensure consistency within the documents of the ISO 18944 family.
