Cold blacks and blues can usually be blended with existing blue with varying degrees of success. I don't know the one you have, specifically, but I generally recommend that after applying one you wet the application with Formula 409 to neutralize the acids. Rinse well with water and apply WD 40 and keep it wet with that for an hour or two to displace any water. Then wipe away the WD 40 and apply regular gun oil or Birchwood Casey Sheath.
Nick
