Old timer's fender welding trick actually saved me 2 hours today

A retired guy named Pete over at the Denver shop told me to skip the copper backing bar and just use a wet rag clamped behind the panel when welding thin fenders. I always thought that was hack stuff, but I tried it on a 2015 Focus quarter panel this morning and it worked way better than I expected. No burn through, minimal warping, and it took me about 40 minutes total versus the usual 2 hours plus grinding. Has anyone else used this method, or is there a reason I should stick with the copper bars for production work?

2 comments

2 Comments

gibson.troy3h ago

Ngl, that wet rag trick sounds sketchy as hell but I get why it worked. My buddy Dave runs a little body shop out in Ohio, and he swears by the same thing for old Mustangs and Camaros. He had this one 68 Firebird where the quarter panel was so thin you could practically see through it, and the copper bar just kept pulling the heat wrong. He finally tried the wet rag clamped on with wooden clamps, said it steamed like crazy but the metal barely moved. Took him way less time to finish than his usual setup, and he still does it for rusty cars where the metal is iffy. I think for production work with fresh panels the copper is still safer, but for old junk or thin factory stuff, the rag method has a place. Honestly, if it saves you two hours and doesnt come back with a call about warping, run with it.

taylor_wells3h ago

Holy crap, the wood clamps make all the difference huh? I wouldve figured the metal would just suck the heat out of the rag and warp anyway, but I guess wood dont conduct the same way as copper. That 68 Firebird story is wild, you could see through the panel and it still held up? Sounds like Dave found a magic trick for rust buckets. @gibson.troy you gotta tell him to do a video next time, I wanna see that steam show.