It has been recognised that NDT staff have a need for a measure of colour vision perception that is linked to the NDT method being applied. For many years there was no potential cure or corrective action available for those people who have colour vision deficiencies, typically 10% of the male population. ISO 9712: 2012 states: ‘b) colour vision shall be sufficient that the candidate can distinguish and differentiate contrast between the colours or shades of grey used in the NDT method concerned, as specified by the employer’.

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