This pen features our recently introduced most sensitive ink developed to-date, the Validator. This ink is changing colour from clear/colorless to gold/brown and often, on most active materials, will work even under ambient illumination. This ink is the most sensitive, given the most impressive visuals on almost any material claiming to be photocatalytic i.e. self-cleaning.
It is not suitable for reactive surfaces which have chemicals present that are able to trigger the colour change. Although not common, this false colour change is usually seen in the dark (i.e. without irradiation) and in such cases none of the photocatalytic indicator inks are likely to be appropriate. If in doubt which ink to choose to test your substrate – please send a sample of the material and we’ll be happy to advise on the most appropriate ink to use.