Ammonia, salt and lemon juice.
Mr. Clayton Cook purchased a set of Sögreni Copper Pedals, but he had a plan how to make them look a little older. Mr Cook writes: “Here are some pictures of your copper peddles. I love old “green” copper so, I found a recipe on the internet about how to artificially age copper quickly so it will look old! Basically it is a mixture of ammonia, salt and lemon juice. One of my favorite details about artificially aging the copper was that the peddles got shiny where they contact the soles of my shoes”. Nice tip if you want your bicycle to look more vintage – thanks for the pictures!