1. Understand the purpose of using special welding gases. It is to provide a shielding cloud around the molten metal. This shielding effect excludes oxygen and nitrogen from around the weld, keeping contaminates away.
2. Know the different types of shielding gases and the different effects they have on the weld. If you are welding in the short arc mode, straight CO2 is preferred. The advantage of CO2 is the long-lasting bottles and is relatively inexpensive.
3. Consider spray arc welding. If you are using this mode of welding you will want to use an argon CO2 mixture that is no more than 20 percent CO2. This will give you not only a cosmetically appeasing weld, but also one of deep penetration and a high deposit rate, which gives you a stronger weld.
4. Use straight argon gas for aluminum, stainless steel and other types of weaker metals.