I have only used a sand blaster. It does a great job and it’s $8 per 50 lb bag. Soda costs much more, but I would like to invest in a nice pressure washer with a soda attachment. I spend all my $$ on tools so maybe someday it will be a big purchase.
That is a great question. I would like to use a rust proofing gun setup with different wands, but for now I use a spray can. I access the cowl through the firewall from the removable panel on the drivers side and through the wiper motor opening. Dog legs are tough but I can get in there pretty well. The quarters, and lower door skins, I soak them with POR-15 metal prep so it has zinc phosphate on the inside before I install them. So, now I can spray it with POR 15 on the inside before I undercoat. Also, I use seam sealer on every seam that is exposed. Here is what I am using for now (attached below). A wise member here on Mud showed me the light on rust proof spray cans, these are pretty sweet. It has a hose with a 360 degree fan, and has sealant, zinc phosphate and rust killer all in one. There are other brands also but I am using this for now.Just want to say you do amazing work!
I have a question for the sheet metal expert. When you perform rust repair where you can’t access the back side, like new metal in a front window channel, when you weld in the replacement metal, how do you protect the backside (Primer and Paint) to keep it from rusting after it’s welded in?