Debate: is it worth annealing aluminum before shrinking, or just a waste of time?

I was at a shop in Portland a few months back, watching a guy shrink a dented hood on a '72 Mustang. He spent 20 minutes annealing the aluminum with a torch before even touching it. Then another guy walked over and said he never anneals aluminum, just works it cold and lets the metal do its thing. The first guy swore it prevents cracking and saves time in the long run. I've tried both ways on a few fenders, and honestly I'm still on the fence. Has anyone else run into this debate at your shop, and which way do you lean?

2 comments

2 Comments

ramirez.daniel9d ago

My old man used to work at a Gulf station back in the 80s and a guy came in with a smashed up aluminum boat trailer saying it had to be fixed 'hot' or it'd crack. He tried it cold and it split right down the middle, took two tries with a torch to get it right.

young.emma9d ago

Honestly, I gotta push back a little here @ramirez.daniel. My grandpa was a welder his whole life and he swore aluminum was actually easier to work cold if you knew how to prep it right. Like, heating it up can cause more stress points if you don't know the exact temp to stop at. The guy probably got lucky with the second try or maybe the metal was just forgiving that day. Plus, a lot of boat trailers from the 80s were made with different alloy blends, some were way more brittle than what you get now. So maybe it wasn't about hot vs cold, but just bad luck with the specific metal. I'm not saying you're wrong, just that there's two sides to it.