A: 1) What kind of a furnace? Box, Continuous, Vacuum? 2) What type of flux or atmosphere? Flux, Exo gas, N-H, DA, Vacuum? 3) 12L14 In an atmosphere will vaporize surface lead into the furnace - Bad 4)BAg-13a in a good furnace atmosphere should leave no residue and steel should come out bright and clean - 5) there is not enough information to provide an answer - Please provide more details. Bob Peaslee