Over time, the screws will age and a natural patina will form on the surface. However it is possible to speed up the process using ammonia.
1. Using a gentle household soap or a rubbing alcohol, clean the surface of the screw
2. In a glass, place a few drops of ammonia and then add the screws. Cover the top of the glass and leave the screws to soak.
3. After 10-15 mins a discoloration will occur and the screws will be ready to clean and use. The process can be repeated for further results.