What is ISO 18941 about ?
ISO 18941 describes the equipment, methods, and procedures for generating a known ozone exposure and the subsequent measurement and quantification of the amount of change produced within both digitally printed hardcopy images and traditional analog photographic color print images due to that exposure.
The test method described in ISO 18941 uses increased levels of ozone to achieve an accelerated test. If the principal “gas fading” mechanism for a system is not ozone, this method might not be suitable and might give misleading results as to resistance of the test image to polluted air.
Who is ISO 18941 for ?
ISO 18941 on test method for ozone gas fading stability is useful for:
- Photographers
- Imaging materials manufacturers
- Quality and stability assessors
Why should you use ISO 18941 ?
In image permanence testing, there are four environmental variables known to affect the stability of a photographic image: heat, light, moisture, and air pollution, such as ozone. Although natural aging under “real-world” environmental levels of these variables is considered the only certain test for image permanence, the high stability of most modern photographic products makes testing under ambient conditions too lengthy a process to be of practical use.
ISO 18941 covers the equipment, methods, and procedures for generating a known ozone exposure and the subsequent measurement and quantification of the amount of change produced within a photographic image due to that exposure. It is important to note that if predictions of absolute product longevity are of concern to the experimenter, then further knowledge shall be gained regarding the reciprocal behavior of the test product under the experimental accelerated ozone conditions.
ISO 18941 has been primarily developed via testing with inkjet images on porous “instant-dry” photographic media, which have been shown to be susceptible to fading by oxidative gases present in polluted ambient air. While many chemical species may be present in polluted air, it has been shown that most of the fade observed for current inkjet systems can be explained by oxidation by ozone. Additionally, this method may reasonably be used for colour photographic images made with other digital and traditional “continuous-tone” photographic materials such as chromogenic silver halide, silver dye-bleach, dye transfer, dye-diffusion-transfer “instant” and other similar systems.
What’s changed since the last update ?
BS ISO 18941:2020 supersedes BS ISO 18941:2017, which is withdrawn.
The main changes are as follows:
- The test methods for environmental stress factors have been changed to align with ISO 18944:2018
- The calculations and computations section has been removed as they are now contained in ISO 18944:2018
- 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 ISO 18944 family
