Stainless steel and titanium pots can be used over an open fire, but you should use caution. When using them over an open flame, some soot may accumulate, and the pot may warp if exposed to high heat. However, aluminum cookware is not recommended for use over open fires due to its plastic parts, which can melt. It is best to use cookware specifically designed for use over open fires, such as cast iron cookware, which is more durable and better suited to withstand high temperatures.