a white led is just a blue led with some yellow phosphor paint on it ... blue + yellow = white to our eyes
so the blue bottle is just filtering out the yellow ... blue should get you more light.
it would be interesting to try royal blue (455nm), which is a much deeper more violet color blue ... I haven't see royal blue in small LEDs, just the Luxeons, but I think the deep blue color would cast an interesting glow
of course the royal blue can bug your eyes too, they are really bright, but at the same time, appear dim, weird
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now Alan, if you really wanted to be fancy, you could build a
joule thief and run your LEDs off a single AAA
