Re: Does lighter food coloring dissolve or evaporate faster than darker ones?

     If the food colors are all water-soluble, there probably shouldn't 
be any noticeable difference in the time it takes them to dissolve. When 
you say that the pineapple kept its color the longest, it may be that 
what you have tested is how long it takes a candy cane to dissolve; did 
you test more than one cane of each color, and were the results the same 
each time? If you are measuring to when it loses apparent coloring, do 
any of the canes have white cores as opposed to being colored completely? 
If they do, you may be effectively measuring the thickness of the colored 
coating, not necessarily the rate at which it dissolves.
     What you may be thinking of is fading; if you have two pieces of 
fabric, or construction paper, one that's a pale color and one that's 
dark, the dark one will generally appear to stay colored longer when 
exposed to something, like the sun, that destroys pigment. So a pink or 
yellow ribbon will appear to fade faster in the sun than a navy blue or 
forest green one (assuming that the ribbons are made of the same 
material).

Hope this helps!