This is mostly a habit from when making brass where I wait until the copper has melted before I add the zinc, to minimize the amount of zinc oxidizing and burning off. I believe this is less critical with Bronze where the tin is less likely to oxidize quickly.
Very fascinating and such a nice end result!
Why do you add the tin after the copper has melted rather than putting both in the crucible at the same time?
This is mostly a habit from when making brass where I wait until the copper has melted before I add the zinc, to minimize the amount of zinc oxidizing and burning off. I believe this is less critical with Bronze where the tin is less likely to oxidize quickly.