To Tone A Scratch: Place a small dab of Deller's Darkener on a toothpick and gently fill the scratch. When the color of the scratch matches coin, wipe off the surplus darkener and allow it to set.
To Retone Cleaned or Spotted Coins: First, clean the coin with a quality coin solvent (such as Koinsolv) to be sure it is free of foreign matter or oils. Then, place small quantity of Deller's Darkener on a cotton swab, or preferably on a bronze/brass brush and gently rub it on the coin until the desired tone appears. Wipe off the surplus darkener and allow it to set.