There are two other types of flames that you want to know about here. You can have an Oxidizing flame and a Carbonizing flame. The Carbonizing flame (more Acetylene then Oxygen) is a hotter flame. This can cause you to have a hard time cutting, because the metal gets overheated. This will cause warpage on thinner metals and cause large amounts of slag on thicker material. When this happens the thicker materials wants to weld itself back together and the cut won't drop away cleanly. Oxidizing flame (more Oxygen then acetylene) has a cooling affect, that makes it hard to keep the cut going, because it cannot get the metal hot enough (molten) to allow the material to be blown away by the high pressure Oxygen stream.