Step 8: "Painting" the Structure
I hate elastomeric roof sealers. Once you paint your roof with elastomeric sealer you can never get cement to stick to the roof again and you are trapped into potential elastomeric nightmares over time. Instead, I use a cement base sealer called Thoroseal. It never peals or blisters, but does weather away gradually from sun and rain. The Thoroseal is expensive. To protect it, I then put a coat of colored cement over it, like paint. The colored cement is a cheap, sacrificial layer. When I see white Thoroseal showing through it, I know it is time to apply more colored cement.
I use broom heads as brushes to paint with. For the final touches, I sometimes splatter on more diluted solutions to get mottled color effects.
For more painting-with-cement info see: http://www.instructables.com/id/Painting-with-Colored-Cement