There are a multitude of commercially available products that will clean and shine copper, and there are simple steps any homeowner can take that will help to keep those objects shinny for a long time. You'll be happy to know that you don't need caustic chemicals to make your copper shine like a new penny. Using just a few simple household ingredients any homeowner can clean and shine almost any copper item. And keeping your copper looking like new is merely a matter of sealing it against air and oils.
Mix 3 cups of pure concentrated lemon juice with 1 cup of salt. Stir until all of the salt has dissolved.
Dip your sponge into the lemon juice and salt mixture and then rub vigorously on a tarnished copper item. In many cases this is all that will be needed to erase years of tarnish and bring back that golden luster to your copper item. If the tarnish is stubborn, add one cup of white vinegar to the lemon and salt mixture and try again. If the tarnish still refuses to come off add 1/2 cup of ammonia to the lemon/salt/vinegar mixture and try once again.
Make a final pass of your cleaning mixture over your copper item while wearing gloves. Pay particular attention to cleaning any areas your fingers or any other exposed skin has touched. Rinse your copper item thoroughly while wearing gloves. Do not touch your clean copper item with your fingers or any exposed skin as the oils from your skin can tarnish copper almost immediately.
Spray a light coating or lacquer on all exposed copper, being careful not to touch your copper object with your naked fingers. Allow the object to dry for at least 2 hours or per the instructions on the can of lacquer. If necessary, spray one side of your copper object, allow to dry and then spray the other side. Allow the entire object to dry for at least 2 hours or per manufacturer's instructions.