Have you seen this man's work? UNBELIEVABLE!!! "River's and Tides" is a MUST SEE!...it shows him creating some of his work. AMAZING! You really can't appreciate it until you see how he works...baffles my brain!
You can search his name on YouTube and see snippets of the movie... in the meantime....
In this video the red that you see him add to the stream was created from rocks that he found by the stream...he crushed them until he got powder. He only uses what he finds at any given location...he doesn't bring it there.