The hardest part is getting someone to focus on penetration. It really irks me how many people take that for granted with aluminum, and is the condition for probably 80% of the repairs I have to do on others work.
Perfect example. The easiest joint to do in aluminum is an open corner weld. This is what happens when people don't understand the keyhole and penetration, or just don't care past pay day. This happened on 10 of these 300 gallon diesel tanks. When I prepped it for rewelding, I barely hit it with the milk wheel and I could still see the unwelded inside corners of 11 gauge. I mean, how the heck do you not penetrate an open corner on 11 gauge?
![Image](https://sphotos-a.xx.fbcdn.net/hphotos-ash4/302197_2231398898602_1949562159_n.jpg)