I've worked with soda (gov't contract specifies it) and it will not remove heavy rust. It will clean up light corrosion on aluminum, and will remove light or flash rust if you lay on it long enough. I usually just blast the paint off and then clean up the rust with a scotchbrite wheel, it's quicker that way. The primer I use - white zinc - doesn't seem to have any adhesion issues with the soda. Some of the organic medias (pecan and maybe walnut shell) leave a light oily residue on the blasted surface. Haven't used them on anything that was be painted so I don't know how that works out. Heard of some shops using ground up corn cobs, which from all reports seems to be about as aggressive as sand in terms of cleaning, but won't heat up the metal and doesn't leave any oil behind like nutshell abrasives.
I had My coupe done last year they used some kind of media on the rusty areas and where there was any bondo and Soda on the rest. It was nice! it cost $400.00 plus (I think) $60.00 for a gallon of nuetralizer. I welded all my patch panels in then pressure washed the shit out of it inside and out then pressure washed it with the nuetralizer then scotch pad scubbed it again with the nuetralizer just to be safe. I personally like the idea of soda but it has to be prepped right and the car has to be stripped down bare the soda will get in every nook and cranny there is. in the pic you can see the difference from the media blast to the soda
got my 51 merc walnut blasted while my merc was on the frame. No issues at all; slddnmatt took it to a place in so cal. $800 bucks. It came back clean. I have also ground a 65 mustang undercarriage to bare metal myself and i will never do it again (effin mess). Check out both cars on my albums; you can see the before and after on the merc. Soda is fine too; just not sand on panels. dont over analyze this. Save your time, worry and headache on the countless hours of metal work, blocking and painting that follows. best of luck.
I just brought home a 38 coupe that had been soda blasted around May 09. Body was completely dissected, nothing left but metal. It was stored in heated garage. It really has not developed any oxidation at least to the eye. I'm sure microscopically the process is occurring even though a film was left from the blast. These threads are invaluable for research. I have talked to the PPG paint supplier about epoxy primer and talked to some shops. You get a variety of opinions and answers. One shop says they will not touch a soda blasted car for paint. I have to agree it is all about the neutralization process and cleaning. I plan on working the headlight housings first as experiment. I first blasted them in a cabinet with black beauty, hope it didn't impregnate the metal with the soda film. Next I will wash in vinegar, then scotchbrite with acid wash metal prep, then epoxy primer. I have to agree, the way to go is aluminum oxide with a reputable blaster. The soda has its advantages for some applications but overall cars I would stay away. There are so many stages after the soda blast I do not think it is worth it. I came into the 38 on a fair deal so it will be worth the process. One question for those that have experienced the paint peel off. What time frame between blast and paint and then from paint to peeling? Thanks for reading all this.
Oh, can anyone list the neutralizer products to use? And at what PH value should the metal surface actually be for proper adhesion of Epoxy Primer? Also has anyone used Transtar Epoxy Primer? Thanks again. "An ounce of prevention is worth a pound of cure", so they say!
The neutralizer is called "HoldTight 102." I had my Duster blasted last month, and here's what I learned. It will take off light surface rust, and it'll blow off the scales, but it won't deep-clean rust pits. For that, my shop uses crushed glass on just the rusty areas. It will remove Bondo and other body fillers, without heating up the panel. It'll remove 40-year-old undercoating... even the shit that was 1/4-inch thick. It'll remove seam sealer. It leaves a protective layer after blasting that is a natural rust inhibitor. It's that layer that has to be neutralized. It's been in my garage for about a month, without the final wash/neutralizer, and it shows no signs of rusting. This is particularly important, because I screwed the pooch two weeks ago: I had the south-facing garage-door open, and we got a rain storm. It has never rained into my garage more than a foot with the door open. Well, the wind blew the rain all the way back to the back wall! And not just a little mist--the floor was soaking wet, my lathe was dripping, as was the car. I let it air-dry, and you can clearly see the re-constituted soda covering the car... but we've had high humidity since, and after two weeks, there's no sign of flash rusting. Someone mentioned "contouring" the metal with a D/A for paint adhesion? My question is "Why?" The factory didn't, why do I need to? -Brad
What a great article, I had planned on having my body shell soda blasted, and had intended on using epoxy primer, I knew nothing about the coating soad left, reading this article has most likely prevented an expensive disaster for me Thanks to all who posted info here !!
Research your blaster, see who does a good job in your area. I hired a mobile blaster after talking to a few painters in the area, he was recommended due to zero warpage and being professional and on time, he was a body man/painter for 20 years, and races in the area. He used walnut shell, sand, fine grit, and garnet on the floors for a fast cut, he switched media for the area and what we found. I DA'd the car with 80 grit and used acid etch. Blasting was worth the money for me, I didn't have him do the underbody, next time I'll have the car on a rotisserie and have it all blasted. I have never seen Soda remove rust from pits.
On a related note, it also works very well on carbs. I made one of these and it works good for blasting carbs and small stuff: http://www.how-to-build-hotrods.com/soda-blaster.html
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