Most of the oxyacetylene welding is done with

The neutral flame is the flame in which the amount of oxygen is precisely enough for burning, and neither oxidation nor reduction occurs. A flame with a good balance of oxygen is clear blue. The reducing and neutral flames are useful in soldering and annealing.
The neutral flame has a one-to-one ratio of acetylene and oxygen. It obtains additional oxygen from the air and provides complete combustion. It is generally preferred for welding.