Derusting a shell

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BCjohnny
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Derusting a shell

Post by BCjohnny » Fri Aug 08, 2014 7:40 am

Done a bit of digging but still not sure which way to go, a bit outside of my normal field.

Cherry Cougar XR7, '68, interior fire (it was not the only thing that was gutted). After being hosed down and standing, the cabin is rusty.

I'm against dipping it (acid seep out over time), maybe baking too. Only thing that seems to make any sense is media blasting. Plastic might work, soda would but is costly over here. I have my own blast equipment, and experience.

Won't even attempt to restore it, more a case of restifying.

Any long term practical experience?
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon

ZIGGY
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Re: Derusting a shell

Post by ZIGGY » Sat Aug 09, 2014 10:12 am

Have you searched http://www.jalopyjournal.com/forum/ ? Lot of crap like any forum but I'd bet on some good sources there with
long term results from salvaging burned & rusted bodies.

BCjohnny
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Re: Derusting a shell

Post by BCjohnny » Sat Aug 09, 2014 11:39 am

Thanks for the reply. I'll take a look at what they say.

I may have already been on there digging, IIRC some guy built a great big tank and filled it full of diluted molasses to dip a cab or something. It leaked........ :shock:
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clshore
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Re: Derusting a shell

Post by clshore » Sat Aug 09, 2014 3:55 pm

Cheap used (leaky?) above ground swimming pool, chicken wire on bottom, 2x4 on top.
Lay body on 2x4, erect pool sides, fill with water and add phosphoric acid as electrolyte.
Phosphoric acid is used by body shops to prevent rust bloom (Ospho), also as a disinfectant at Dairy Farms, so try Tractor Supply etc, for cheap source.
Connect battery charger, one lead to chicken wire, one lead to shell (lookup which lead goes where, I forget)
Cook until rust is gone.
Drain and rinse, spray with more diluted phosphoric acid solution to prevent re-rusting.

chimpvalet
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Re: Derusting a shell

Post by chimpvalet » Sun Aug 24, 2014 11:14 am

A buddy is having very good results in de-rusting small parts using the Borax, bucket and battery method. For a large piece like the bodyshell you might do well to find a capable blasting man who works in state-of-the-art media. My Lotus chassis was very well cleaned up with no damage by careful blasting with crushed garnet, as far as I know.
Steve

Greg2
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Re: Derusting a shell

Post by Greg2 » Sun Aug 24, 2014 2:31 pm

Maybe contact this place? It's chemical immersion but it wouldn't hurt to at least talk to them.

http://www.surfaceprocessing.co.uk/

BCjohnny
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Re: Derusting a shell

Post by BCjohnny » Sun Aug 24, 2014 3:29 pm

Thanks for the various replies......

chimpvalet

Crushed garnet would be too fierce for panels, fine on a chassis though. Soda would be ok. I've plenty of blasting experience, have a pressure pot etc. Apart from being messy, difficult to get the media all out and the risk of moving the metal around, getting into all the nooks and crannies and box sections is going to be nigh on impossible......

Greg2

Yes, looked at them, they're local to me about twenty miles away. There are a few companies nearby that offer the service, I just keep coming across reports of 'seep' out from seams over time etc ruining paintwork from any of the dipping processes. I know from having stuff zinc plated you can forget anything that has 'joints' or 'laps', the acid will always 'burn' its way out over time. Also, it comes in at over $2k to get all the processes done......

clshore

Yes,I agree the phosphoric acid route looks the most promising. For a 'one off' it's a bit of an undertaking though, and I'm not sure how it deals with sealer/filler......

These guys 'over there' seem to have plausible answers, so has anyone got first hand experience, over time? If so maybe I can find a company 'over here' that uses the same processes......
"If an honest man is wrong, after demonstrating that he is wrong, he either stops being wrong or he stops being honest." Anon

BigBlocksOnTop2
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Re: Derusting a shell

Post by BigBlocksOnTop2 » Sun Aug 24, 2014 10:46 pm

Blast with walnut shells.

Greg2
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Re: Derusting a shell

Post by Greg2 » Fri Aug 29, 2014 6:38 pm

BigBlocksOnTop2 wrote:Blast with walnut shells.
But remove the walnuts first. :)

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Re: Derusting a shell

Post by pdq67 » Tue Mar 17, 2015 9:35 pm

I was at a nat meet somewhere at sometime years ago and a guy was hawking media blasting 'Vette f/g panels.

He had in his hand a pepsi can that he blasted to show just how gentle media blasting can be IF you know what you are doing.

I think he used something like polyethylene, polypropylene or polycarbonate "sand" as his media?

I also have read where they are using dry ice grains probably through an insulated "gun" as a media. Good thing about it is that it turns to C02 and doesn't contaminate anything.

pdq67

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