• Fluorescence: a light source (usually black-light) is needed: e.g. when you see the optical brighteners of the washing powders used for your clothes light up in a disco. When the light source is stopped, also fluorescence stops.
• Phosphorescence: a light source is needed to charge up the phosphorescence molecules: when the light source is stopped, the light is still emitted and visual. Sometimes modern phosphorescent pigment “glow in the dark” for more than 20 hours and are based on aluminum silicates. They have been discovered about 20 years ago.
The chemical nature of aluminum silicates is an inorganic salt like ‘kitchen salt’. They are not dangerous chemicals and not radioactive (have nothing to do with the technology used on 1960-70 clocks). You can buy body paints based on aluminum silicates.
Jef standing in front of a phosphorescent work press button " dark".
Charge up time:
o Direct Sun light 1 min
o Black-light TL lamp 2 min
o Day light 10 min
o Standard TL lamp 30 min
o Edison lamp 60 min
• A 70 x 100 cm work of Jef Keustermans in the hall-way will give enough light to go safely to the bathroom at night without using any light source. Be aware, for some people such a work may prevent you from sleeping in the bedroom because of too much light.
• Jef Keustermans works which employ phosphorescence features are called “Nightvision”. Usually you find a button “Nightvision” to get an impression how the work will be glowing in the dark;