Rust removal inside double paneled car

[fred26t]

I was trained to Mig weld patch panels. For that system you can usually get by with just wire brushing off the inside edge of the patch. I would like to reduce Heat affected zone and learn to TIG my patches. I know well that TIG requires really clean steel. Sand/soda blasting the inside of a double paneled car like the rear of an El Camino does not make sense nor can I afford to do that.
My present thought is after the patch is ready to weld to use a small rotary brush and clean with acetone.
I also have trim holes for the old rubber bumper strips I would like to fill (you can't but the rubber anymore). These are 1/4" holes and some 1/4X1/2" holes.
Could use some help. Fred26t

[Marty Comstock]

If you can get to the backside, cleaning is a breeze, use your favorite method you always use.

If you cant get to the backside, i wouldn't recommend TIG welding, because you cant get a dolly back there to stretch the distortion from the shrunken HAZ.

TIG welding has more inherent distortion and a wider HAZ than MIG. Its just easier to get rid of the distortion because of a softer weld, and much less buildup to grind.

Marty

[fred26t]

I just remember seeing the fast tig welder on the '53 Buick door. But maybe mig is best. Fred26t