|Back when the canoe was purple.|
Not all colours fade at the same speed. Red is the least stable, and blue seems to last longest. Why is that?
What Makes Colour & What Makes it FadeColour comes from pigment either naturally or by adding it. (Tulip colour is natural and paint has colour pigment added to it.) Air and sunlight break down the chemicals in that pigment colour, though, and so can the other substances the pigment is mixed with, like plastic. Sometimes a reaction creates oxygen, and that bleaches the colour too. Heat and humidity can speed this up; they tend to speed up all reactions.
Colour Wavelengths MatterThe longer the wavelength of absorbed light is (which causes the colour we see), the faster it will break down. Even the longest colour wave is stupendously small; you could fit almost 1600 wavelengths of red light into the width of a human hair.
|Blue is in the 400 nm range of wavelength and red has much longer, weaker waves up in the 700 nm range. Red fades much faster than blue.|
|The red faded from my purple canoe, leaving behind only the blue in the mixture after 20 years. The purple underneath peeks out after sanding.|
Colour to LastIf you were making something to sit outside in the sun for a long time, what colour would you make it? Look around you: Does it look like makers tried that? What colour are tarps? How about tents or sail covers?
|To preserve cave paintings, we limit their exposure to light, heat, and humidity by limiting how many people can visit them. People bring heat with their bodies and humidity with their breath, as well as lights to view the paintings.|
Colour to GoWhat if you wanted to get rid of colour? How could you use what you know about light and oxygen to bleach something?
|How are colour fading facts being used to get this laundry bright white?|