Mix flour, white vinegar, and salt in equal parts in a bucket. For example, if you add 2 cups of vinegar, add 2 cups of salt and 2 cups of flour. Mix all the ingredients thoroughly so a paste is formed.
Apply the paste to the copper on your roof, then scrub it vigorously with a nylon-bristled brush to remove oxidation and discoloration.
Rinse the copper roof thoroughly with a garden hose to remove all traces of the paste.
Buff the copper roof with a cotton cloth. Buff the copper until it reaches the desired shine. If you notice discoloration in places, spot clean again with the paste.