Understanding UV in AltProc

UV light and Alternative Processes

UV is outside the visible light spectrum. The light we can see ranges from Red through Green, Blue, Indigo and Violet. At the extremes we have light that is of interest to photography but which is not visible – Infrared and Ultraviolet A, B and C. It is the UV A and B that concern us in Alternative Processes.

The technical measurement of light is in nanometers, ie 1/1,000,000,000 of a meter. So very small. The UVA band, which is the beach tanning band:

  • UVA  315–400 nm

Then UVB which is the skin burning band:

  • UVB  280–315 nm

The UVC band doesn’t really concern us as it is usually filtered out by the Earth’s atmosphere but it is the skin cancer band:

  • UVC 180–280 nm)

Only very specialised equipment creates light that is accurately in a given UV range.


The best specialised source of UV is the Sun. It gives you the UVA/B range in clean parallel rays.

UV Tubes

The best consumer source of UV light is UV fluorescent tubes. But it depends a bit on what UV range they cover.


The UV LED area is quite complicated. We can source LEDs across the UV spectrum – if you have the money and equipment to to control them.


Black Lights