KEEPONTUCKIN
+1y
To you southerners ,I dunno how much it matters as far as waterproofing seams but it sure matters up here...Kitty hair is stronger than bondo,and waterproof,so your seams wont bubble,and really shouldnt crack as long as your combo fits and is fitted right and welded solid...weld,grind(40ish grit),KITTY HAIR,bondo,2 part,prime...(sand in between of course)
Your guy likes kitty hair,but theres other ways that are just as good if not better,you can use kitty hair,pure metal/metal to metal(also waterproof),or if you want you can even lead/solder it.....personal prefrence really,but the kitty hair is a good way to go...
best way of course is to metalfinish/file but most people dont want to pay for that kind of labour.