ISO 18930-2011 pdf free download.Imaging materials — Pictorial colour refection prints — Methods for evaluating image stability under outdoor conditions. During the course of the test, the colour changes in the printed samples are periodically evaluated instrumentally. Results are compared to the initial values for the same specimen prior to testing, and also to a control sample maintained at ambient conditions with light excluded. A further internal control sample with known weathering behaviour is also recommended for laboratory experiments. The change of the test specimens and the reference samples is reported as optical density and/or Lab (or colour difference, ΔE ab ) before and after the test. For an accurate assessment of outdoor performance, an ozone test such as that described in ISO 18941 should also be considered, as many colorants are sensitive to atmospheric pollutants. An ozone test is recommended for media that is unlaminated. However, ozone testing is not a part of this International Standard. 4.2 Outdoor weathering tests Outdoor exposure conditions can vary by orders of magnitude in irradiance depending on the geographical latitude, altitude, specimen orientation, season and weather conditions. Outdoor weathering services are available for some typical climatic conditions, e.g. South Florida’s subtropical hot and humid climate and Arizona’s hot and dry desert climate. A list of common outdoor test sites is given in ASTM G7. Due to the annual variations in climate, it is recommended that internal control samples with known behaviour be included in outdoor weathering experiments. 5 Signifcance and use 5.1 Accelerated laboratory weathering tests Controlled laboratory tests are often used to provide standardized data and to benchmark materials. Predicting outdoor image display life from controlled laboratory tests without correlation data for the material in question between the laboratory test and natural outdoor exposure is not recommended. Since the ability of images on digital printing media to withstand colour changes is a function of temperature, humidity, air pollutants, light and diurnal changes of environmental parameters, it is important that print stability be assessed under the conditions appropriate to the end use application. The laboratory procedure described in this test practice is intended to provide a means for predicting the behaviour under actual outdoor exposure. Test results are useful for specifcation acceptance between producer and user, for quality control, and for research and product development [20][21] . 5.2 Outdoor weathering tests Real-time outdoor exposure is the most reliable method of assessing outdoor image...
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