What does a bright green flame on the tip of a soldering iron indicate?

A bright green flame on the tip of a soldering iron typically indicates that the tinning is burning off. Tinning is the process of coating the tip of the soldering iron with a thin layer of solder, which helps with heat transfer and prevents oxidation. When the soldering iron overheats, or if the tinning is of poor quality or oxidized, it can produce a bright green flame as the tinning material oxides and burns away.

Recognizing the significance of this bright green flame is essential for anyone involved in HVAC sheet metal work or soldering tasks, as it suggests that the soldering iron is not functioning optimally. Maintaining the integrity of the soldering iron tip by ensuring appropriate temperature and proper tinning will lead to more efficient soldering and longer tool life. Thus, while the other options may refer to temperature status or performance, the presence of the bright green flame is a direct indicator of tinning material being compromised.