With oxy-acetylene welding, what shields the weld pool from the atmosphere? Is it the gas produced by the oxygen and acetylene burning? Or do you use filler rods that are flux-coated? (You can fuse parts without using filler metal with oxy-acetylene right? I'm thinking the gas produced from burning the other two shields the weld, but I'm just guessing...)
Dave
You are correct in that the combustion gases from the torch is the shielding. That is one reason why you don't want an oxidizing flame because there is too much free oxygen that will react with the metal.
CHGuilford
When welding copper and copper alloys you must dip the rod tip into powdered borax. The borax melts immediately at the contact with the flame and this is what isolates the metal from atmosphere.
But this is valid only for copper and its alloys.
Giovanni S. Crisi
Sao Paulo - Brazil
It depends on what the base metal is made out of. For instance, You need to coat your filler rod with flux when you weld brass. One of the main contaminents in the air is carbon. If you are welding a carbon steel, you don't need as much protection from carbon as when you are welding copper or brass.
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