I live in Washington, It's almost 1:00pm for me right now. ^_^ I guess the time zones would be very different between Australia and the U.S.
You're right, density isn't the word I was looking for, maybe depth? Like a mirror! There's an example!
If you have two mirrors on opposing walls and you look into one of them the reflections seem almost infinite and the deeper the reflections go, the greener the image gets. A mirror by itself doesn't look green, but the ever-so-slight color is there. And the more layers there are, or the deeper the images get, the more you can see the color.
http://www.youtube.com/watch?v=-yrZpTHBEss
Okay, I just re-watched that and it looks like it might answer both questions. ^_^