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Old 05-08-2018, 10:55 PM   #1
CUDA8U
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Acid dipping to remove rust/bondo

Anyone do this? Good/bad?
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Old 05-09-2018, 05:13 AM   #2
darrellyates
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Re: Acid dipping to remove rust/bondo

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Anyone do this? Good/bad?
My opinion on the dipping process isn't positive. Please remember that everyone has an opinion... And mine is based on input from George Ross of Ross Restorations in Thompson Station TN. George did a '35 Ford pickup for me years ago and we discussed it in depth.

George has several European cars, and really was a British Restoration expert at first. He's since branched out into everything, but he's a tremendous painter and fabricator. Had several Lotus cars, and some stuff I didn't recognize.

Anyway, the issue with dipping cars is that even when cleaned up, the chemical never really comes out of any seams. Then, over time, it continues to "clean" the metal, and eventually eats thru the seam. He showed me on several different cars he had "dipped".

Now, admittedly this was years ago, and maybe the process has improved, however he convinced me to sand/media blast, and I've been nothing but happy with my decision.

Again, everybody has an opinion. Talk to different people who do this for a living, and gauge for yourself. Personally, I won't dip a vehicle body.
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Old 05-09-2018, 05:49 AM   #3
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Re: Acid dipping to remove rust/bondo

I wasn't pleased also, did some hemi blocks and imo it was a waste of money
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Old 05-09-2018, 08:17 AM   #4
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Smile Re: Acid dipping to remove rust/bondo

I did a 56 Thunderbird years ago. I thought that the car was in good enough shape to justify the cost. I wanted to get into the spots that are impossible to do by hand. Well what I got back was enough metal to make a peddle car. I was young, wouldn't listen to anyone, so it cost me $800 big ones, back then. I learned to listen real quick. With the different types of media blasting available today, personally I would pass on the dipping idea for a car or truck. Dipping has its place but I don't think it is good for our jewels. My seven cents worth. Have a good day and good luck eh!
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Old 05-09-2018, 11:24 AM   #5
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Re: Acid dipping to remove rust/bondo

I've had two done by chemical dip. I was very happy with the result both times.

On the first one I paid extra to have it done late friday and left in the neutralized over the weekend, though whether that helped and whether they actually did it I have no idea.

All I can tell you for sure is that it was 12 years ago and the restoration has held up perfectly.

I have a second one I just shipped off to the body shop. It was also dipped and I'm pleased with everything it got out.

My only problem with sand (when done right) is you can never get it all out. I have to chuckle at the track when a nice car launches hard and leaves behind two little sand trails...
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Old 05-10-2018, 04:11 PM   #6
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Re: Acid dipping to remove rust/bondo

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Well what I got back was enough metal to make a peddle car.
The reason for acid dipping is precisely because of this. You started with crap and got crap. It's not the dipping fault. I did a 67 mustang back in 1987 and was very surprised at how little rust was on the body.
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Old 05-10-2018, 08:11 PM   #7
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Re: Acid dipping to remove rust/bondo

I researched this years ago, so things may have changed. The info I got was that the toxic bit gets in the lap joints (all bodies have lots) and never comes out. Then paint near those joints fails after time. Maybe with a dip neutralization process rather than pressure wash, that could be invalid.
Another issue is now you have clean metal that wants to flash rust unless dipped in a rust inhibitor such as a phosphoric acid solution. Lots of that metal is in places that will never see paint. Crazy as it may sound a dip in some sort of primer is a good answer, but who has a vat of primer?
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Old 05-11-2018, 02:17 AM   #8
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Re: Acid dipping to remove rust/bondo

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I researched this years ago, so things may have changed. The info I got was that the toxic bit gets in the lap joints (all bodies have lots) and never comes out. Then paint near those joints fails after time. Maybe with a dip neutralization process rather than pressure wash, that could be invalid.
Another issue is now you have clean metal that wants to flash rust unless dipped in a rust inhibitor such as a phosphoric acid solution. Lots of that metal is in places that will never see paint. Crazy as it may sound a dip in some sort of primer is a good answer, but who has a vat of primer?
That would be my concern also, no one here in my metro area has a vat that can turn a cab upside down. Like the factory does today.
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Old 05-12-2018, 12:49 PM   #9
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Re: Acid dipping to remove rust/bondo

You definitely need a trip through a neutralizer -tank-. Not just a spray.

I've got pictures of it somewhere, the car goes through a giant tank like at the factory and then into a different tank that neutralizes it. That's why it's not cheap, I suppose.
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Old 05-12-2018, 02:19 PM   #10
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I wonder how often they would have to clean out the tanks with all the crud that is left behind. I think that replacing the chemicals and disposing of them would be a big cost factor also. Have a good one eh!
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Old 05-12-2018, 10:04 PM   #11
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Re: Acid dipping to remove rust/bondo

for smaller parts I have used some of the electrolisis and chemical concoction you see alot of on u tube. its the set up that kinda works like a battery with a battery charger. Its worked pretty good at removing ruts but i dont know about bondo but it did NOT remove RTV/gasket material.

and yes there is a lot of junk in the bottom of the tank. I let the water evaporate and what is left over is disposed of with the local city recycling .

as for future rust prevention as soon as the part is removed from the talk it is sprayed with a high pressure washer that heats the steam to 300 degree's. until the part is very hot, hot enough for the water to evaporate off almost instantly, then spray it with WD40
It can sit for a while and only needs a good wipe down and prep to be ready for paint.

I have done alot of engine part and no sheet metal but the theory is the same, you just have to get clever with the tank design and electrode positioning. I saw somebody submerge an entire and complete exhuaste system for a 63 tempest and do that. the set up was actualy easy. but the electrode location had to be changed to do the entire system. cant be much more complicated than a door.
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Old 05-14-2018, 10:25 AM   #12
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Re: Acid dipping to remove rust/bondo

I soak parts in several solutions. I've used citric acid, phosphoric acid, Evaporust and diluted molasses, All are very good rust removers. So far none of them actually gets the rust out of the seams. Even after soaking for months if you split the pinch weld or unfold a door edge there are still significant rust deposits. It is of note that with most of these most or all of the internal corrosion protection that may have been left is gone once dipped. A commercial dipper would have to be using some nasty stuff to get into the pinch welds and I'd be scared that they didin't get it all out.
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Old 05-14-2018, 03:22 PM   #13
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Re: Acid dipping to remove rust/bondo

I use muriatic acid to dip all small parts in. Rust boils right off. Lots of people are scared to use it for some reason. I’ve been maintaining swimming pools forever and have no problems handling it safely.
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Old 05-15-2018, 11:46 AM   #14
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Re: Acid dipping to remove rust/bondo

Anything the size of a wheel or smaller, I sand blast. I started out with a cheap Harbor Freight cabinet and then added high end Skat gun and light, which is 95% of the battle. That and a good compressor with a dryer, of course.
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Old 05-16-2018, 02:20 PM   #15
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Re: Acid dipping to remove rust/bondo

I can see why you have used that service. The neutralizing tank is likely most important part of the process. Its not just a wash down which will undoubtedly miss many areas that will matter.

Well thought out for sure.
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Old 05-19-2018, 07:08 PM   #16
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Re: Acid dipping to remove rust/bondo

Interesting Process!

https://www.youtube.com/watch?v=kQZloNc_7f0

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Old 05-19-2018, 09:03 PM   #17
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Re: Acid dipping to remove rust/bondo

very interesting but electrolisis or electrolyte method gets in all the nooks and crannies and no acid seaps out later to ruin a paint job.
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