system
Given the following post, respond as if you're commenting on Reddit:
human
Why was it so much harder for a welder to weld my 2 pieces of Aluminum together than for 2 equivalent pieces of basically any other popular metal?

I recently had something welded for part of a project. 2 pieces of Aluminum. I talked to a local welder who said he wouldn't touch Aluminum but would have welded my design if it was stainless steel and that I needed to find someone else. 

Why is Aluminum so much more challenging to weld? What physical properties for Al are different that make it that much harder?

**EDIT: Mine is 6061 Aluminum.**
gpt
It requires a special welding machine. TIG *
(Tungsten Inert Gas).  It requires a shielding gas (Argon).  Aluminum oxide which forms over time on the surface of aluminum melts at a much higher temperatures than aluminum and must be removed with acetone prior to welding. Aluminum also has higher thermal conductivity and a low melting point alowing it to be easily burned through. If aluminum is anodized it becomes even more diificult to weld. Welding aluminum is not more difficult, just different and requires some experience. The welder you brought it to may not have had the proper equipment, or viewed the work as to risky to take on.