Oxidizing and reducing flames

The color of a neutral flame is semi-transparent purple or blue.

When the amount of oxygen increases, the flame shortens due to quicker combustion, its color becomes a more transparent blue, and it hisses/roars.

[2] With some exceptions (e.g., platinum soldering in jewelry), the oxidizing flame is usually undesirable for welding and soldering, since, as its name suggests, it oxidizes the metal's surface.

It has an opaque yellow or orange color due to carbon or hydrocarbons[3] which bind with (or reduce) the oxygen contained in the materials the flame processes.

They don't have an opaque yellow or orange glow, nor do they produce soot or carbon monoxide.