Most artificial dyes are made from petroleum
(The NPR news: http://cbsn.ws/c0gBIR)
I prefer to use natural food colors.
The video below shows how to boil these foods for coloring. I find that the colors are weak when they are made in this way. To get the rich, beautiful colors, I use freeze-dried, powdered extracts.
Red Raspberry makes a beautiful red color and tastes great!
Powdered Spinach makes a beautiful green color
To make black use:
To make yellow-orange you can use:
For purple you can used powdered blackberries
And turmeric from your spice cabinet makes an excellent yellow. 🙂