Answer
Sep 18, 2021 - 07:22 AM
The brass may be dull, may have manufacturing marks such as small scratches or scrapes.
The brass may have manufacturing oils or grease. This can stain the brass in some places.
The brass can be tarnished. After manufacturing, when brass is not sealed with varnish or lacquer, oxidation can start darkening the brass. Since parts are manufactured at different times unfinished brass parts can be at different stages of aging. This would make unfinished parts not match each other.