One of my favorite illustrators of all time is Arthur Rackham.....
His illustrations are so magical.
Illustrations above from Alice in Wonderland
In one of my Illustration survey classes in college I learned that Arthur Rackham used to mix his watercolors with bleach and thats how he got those tones and how he got the bright whites was by actually bleaching parts of his paintings.
I was always so impressed by his style.