Re: why do bubbles only turn white?

Bubbles from soap solutions are made of very thin layers of surfactant 
(surface active agents), so thin in fact that the light reflected from 
them remains the color of the light shining on them. This is not the case 
for bubbles made from very concentrated soap solutions where the 
surfactant layer is much thicker. In this case you see bubbles of 
different colors depending on the thickness of the layer. When you look at 
the outside of the bubble and the surfactant layer is very thin, it acts 
like a mirror. So all you're seeing is reflections of the room lights or 
the house lights or the sunlight - which are usually white in color. This 
is why no matter what color the solution is, the soap bubbles still look 
white.