In painting already painted cedar shake shingles, what is the best paint to use? Is a specific primer necessary? What is Duration? Is it manufactured by Sherwin-Williams?
Thanks for your answers.

Staining may work but paint will not stick to a cedar shake because it expands and contracts too much.

If you want paint to stick to ceder you must apply a shellac alcohol based primer,tinted to the color you wish the ceder to be. After that I high recommend using a premium exterior enamel paint. If duration comes in enamel, and it has a higher particle content use it.