Iso blue wool standards

Abstract Preview Describes a method for carrying out quality control of production batches of the blue wool reference materials 1 to 7 which are to be used in the appropriate parts of ISO B series of test methods for colour fastness to light. Status : Published. Publication date : CHF 38 Buy. Life cycle Now Published. Final text received or FDIS registered for formal approval. The pigment begins to fade in 2 years or less of light exposure, even with proper mounting and display.

A : Blue wool reference strip B : Megalux hours of exposure before fading becomes noticeable. Exposure to average indirect indoor lighting to lux for an average 12 hours a day equals from 0. The grey scale consists of nine pairs of non-glossy neutral grey coloured chips, which illustrate the perceived colour differences.

These are used along side the blue wool samples to determine the corresponding fastness rating as described in ISO A The problem with the blue wool scale and the grey scale is that it is a subjective test i.

Hence it can lead to some variability. Secondly, significant changes on the blue wool scale are not particularly onerous with respect to outdoor performance of most moulded or fabricated products. Whilst it is a useful reference for printed medias and the textile industry, products that require significant outdoor exposure will require a rating significantly greater than the maximum of 8.

Most modern testing now uses colourimeters or spectrophotometers to accurately measure any colour change or colour differences and report these as a Delta Eab reading. A full explanation and interpretation of this technique is supplied with our reports as standard. A brief summary of the LAB colour space is also provide below.

The diagram to the right demonstrates the L, A and B coordinate systen. Grey Scale for Change in Colour The grey scale consists of nine pairs of non-glossy neutral grey coloured chips, which illustrate the perceived colour differences.

Colour Measurement Most modern testing now uses colourimeters or spectrophotometers to accurately measure any colour change or colour differences and report these as a Delta Eab reading. A value of about 1 is just about perceptible to the human eye under normal lighting. ISO Blue Wools The ISO blue wools are each dyed with a different dye giving rise to a light fastness scale which is an approximate geometric progression, ranging from 1 to 8.

How many hours of daylight exposure does each Blue Wool Reference correlate with? Each successive reference taking twice as long to fade to the same grade as its predecessor, e.

The tests are: Instrumented assessment of evenness of the dye Instrumented and visual assessment of the fading characteristics Blue Wool 8 is not suitable to be tested in this way as the time taken to fade to a grade 3 and 4 would be too great and not time effective.

A more efficient method for Blue Wool 8 is currently being devised. And, when not in use, these should therefore always be stored between the black sun protection boards and, if possible, any exposure to light that is not related to the actual test should be avoided.

Final Thoughts Subjectivity and variability of results is something all testing professionals should be mindful of when using blue wools.

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