The Pen

Find out more about the pen

Find out how to fill a PenInk Intelligent’s PhotoCat Pens provide a quick, easy and reliable method of checking whether a surface is photocatalytically active; effectively making the invisible visible!

When the ink from the pen is exposed to ultraviolet light (UV)* it will change colour, but only if it is on a photocatalytic surface. There is no reaction if the ink is drawn onto any other surface. The video below shows a side-by-side comparison of the ink on a normal piece of glass and on a commercial photocatalytic glass.


See our new videos at you tube

BB and MB pen on commercial self-cleaning tile

RZ ink on porous self-cleaning fabrics

PhtocatValid pen  on commercial self-cleaning tile 

BB pen on self-cleaning tile

All the pens on TiO2 sol-gel


*The UV source can be sunlight or BL/BLB light bulbs.
Video shows typical behaviour when exposed to a typical sunlight UVA exposure of 2 mW per cm2.

The PhotoCat Pens work on a wide variety of photocatalytic surfaces including glass, tiles and paint.

Storage: The pens should always be stored in a cool, dark place with the cap clipped firmly on. These measures will ensure that the ink does not dry out and will increase the life-time of your pen.

Ink Intelligent currently offer two different pen models; RZ and MB indicator pens. The RZ pen changes from blue to pink when irradiated on a photocatalytic surface, while the MB pen changes from blue to colourless*

Ink Intelligent RZ PenInk Intelligent MB Pen

*Blue colour will return very slowly if the ink is left on the glass, so ensure to clean thoroughly after use