I watched a video by Charles Lewton-Brain, for ACAD, where he demonstrates annealing (bare copper sheet, no barrier flux) and shows how the flame turns a bright orange when annealing temperature has been reached.
I decided to try this out myself, on sterling silver sheet, using Pripps Flux.
In this instance, the flame turned a bright green, just before the flux went from powdery to glassy, and a millisecond before the flux started to turn rust brown color (similar to how the Borax cone flux turns rusty brown when soldering temperature is approaching.
If I stop at this point, my metal is soft.
If I stop before this point, my metal is not soft.
Has anyone else experienced this green flame? I am wondering if it is a color indication, similar to the one Charles Lewton-Brain demonstrates, which in his case is orange.