Paint and rust removal via caustic/acid dip

Richard Casto · **Posted:** Wed Nov 16, 2005 5:15 pm

Anyone have experience with this? Any recommendations for local vendors who do this?

For those who are reading this that don't know what I am talking about, you can strip a car down to the bare metal, dip the entire car in a caustic bath to remove the pant. then dip the entire car in an acid bath to remove any rust. This is one method to remove paint and rust when doing a complete restoration on a car.

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

Wasn't there a local rally guy that did this in Greensboro?

Rich Anderson · **Posted:** Wed Nov 16, 2005 5:31 pm

Richard Casto wrote:

This is one method to remove paint and rust when doing a complete restoration on a car.

Also a very good way to covertly lighten a unibody that will be subsequently reinforced by a rollcage.

Richard Casto · **Posted:** Wed Nov 16, 2005 6:05 pm

Rich Anderson wrote:

Richard Casto wrote:

This is one method to remove paint and rust when doing a complete restoration on a car.

Also a very good way to covertly lighten a unibody that will be subsequently reinforced by a rollcage.

Probably any weight lost due to the dip will be replaced by the qty of welding I have to do to put back the rusted out stuff.

I also don't plan to go crazy with the cage, so the "reinforcement" aspect of the cage isn't going to be as nice as it could be. No tie in to suspension pickups, etc.

Richard Casto · **Posted:** Wed Nov 16, 2005 6:08 pm

One thing I am looking for is comments (real world examples, not "I heard it from this guy") about the potential for the acid to bleed through and damage the paint the will eventually be put back on the car. There are plenty of anecdotal stories about "don't dip your car as you can't get the acid out of the seams and it will leach back into your paint".

Adam Ligon · **Posted:** Wed Nov 16, 2005 7:09 pm

Matt Johnson, is the rally guy , who had it done. Ask one of his rally buddies they can probably put you intocuh with him;
-Carl
-Andrew

Carl Fisher · **Posted:** Wed Nov 16, 2005 7:48 pm

Yeah, it was Matthew Johnson who had it done. I think the place was actually in Burlington, but he'd know better than me. :-)

I think he said they bake it first (maybe to loosen the paint?), then do the acid dip, the spray it with a rust-preventative. I asked him if the acid would lighten the car, and he said not appreciably.

I know he spent a lot of time hand-washing the shell down with various chemicals, and sanding and sanding and sanding at each step of the way. It all looked like a shitload of work to me, but it certainly did come out looking nice. You'd have to ask him his impressions, though.

Give him a shout at matthew@carolinars.com; he's pretty good about replying, though it might be a few days as he's on the road sometimes.

Here are a few pix (pick the week July 4 - 10, 2004):

http://www.carolinars.com/gallery/

Good luck!

Kevin Hoff · **Posted:** Wed Nov 16, 2005 7:50 pm

I'm not sure Matthew has (or remembers) his logon to this forum.

He did have his WRX dipped at the place in GSO then stitch welded and repainted by a shop here in RTP. For photos of the whole build process look at http://www.carolinars.com/gallery The entire process was a HUGE amount of work, he and Eric both said more than once that doing it again they would have just used the JVL death ray (Google is your friend) as the paint prep was _extremely_ tedious.

It did make for a beautiful finished product though. On simpler older cars, especially ones that are highly rusted and are already going to get stripped to the bare metal, the difference in effort would probably be near zero.

--Kevin H.

<edit - Carl beat me to it!>

Richard Casto · **Posted:** Thu Nov 17, 2005 10:43 am

Guys, thanks for the feedback. I have emailed Matt.

Anyone else know anything about this? I should have also asked if anyone knows of someone who could media blast the entire car as well.

AndersGreen · **Posted:** Sun Nov 20, 2005 10:32 am

Richard Casto wrote:

I should have also asked if anyone knows of someone who could media blast the entire car as well.

Head down to the Rockingham area. I know there are businesses that exist there that do this for the race teams. In fact, I met a dude at a car show from that area who's business was sandblasting *trailers* (not the car-hauling kind, the 18 wheeler kind) and their sandblaster "guns" were apparently like firehoses. Sorry, no contact info though.

Cheers,
Anders

Brad Mackey · **Posted:** Sun Nov 20, 2005 12:05 pm

A few years ago, I restored my MG Midget. It wasn't a rust-bucket, but it had a few problems. The guy who did the difficult panel welding and painting cautioned me about acid-dip or any other caustic chemical processes to remove unwanted paint and rust. he claimed that chemical residue remains in the seams of the car, regardless of how much "rinsing" is performed. He would not do the restoration unless the car was stripped using dry media.

So, I used an outfit called "High-Tech Stripping", off US70, west of Crabtree. They're not in the 'phonebook anymore, so they're prob'ly out of bi'ness. They used a plastic-bead process that was non-invasive to the base metal, but sure took off ALL rust, body goop, undercoating, paint, etc. Very pleased with the results. I immediately had the whole car encased in epoxy primer (same day).

If all you want to do is strip paint an' stuff to prep the car for sheet metal/structural repairs, then I'd stay away from acid or caustic stripping agents, which could linger in pockets and seams, causing problems later.

AndersGreen · **Posted:** Sun Nov 20, 2005 12:14 pm

I just had a related thought. For a rally car, who cares if some leftover acid leaks out over five years... the car's going to be balled up in four! :twisted:

For a restoration, there are different long term (next 30 years... next 50 years?) considerations.

This may be one of those "proper method for proper problem" decisions that doesn't have a "method #1 is always correct".

Anders

Brad Mackey · **Posted:** Sun Nov 20, 2005 1:52 pm

Anders, yeah, I did a 100-year restoration, not a short-term deal.

But the problem is not the acid/caustic leaking out. That would be a good thing. Rather it is the acid staying captured in the seams and crevices, being free to do its evil, dastardly, even vulgar deeds, unseen by the hapless owner. The damage would be effected in a matter of a few short months (all Februarys, I would imagine).

The horror would continue unabated until, alas, the vehicle would collapse in a jumble, useless, its owner heartbroken and confused....

Uhhhh.... now where was I? Ah, yes. Like I said: Acid dip's probably OK for short-term projects, but I would choose blast media, if for nothing more than the environental impact

Richard Casto · **Posted:** Sun Nov 20, 2005 2:08 pm

Brad Mackey wrote:

So, I used an outfit called "High-Tech Stripping", off US70, west of Crabtree. They're not in the 'phonebook anymore, so they're prob'ly out of bi'ness. They used a plastic-bead process that was non-invasive to the base metal, but sure took off ALL rust, body goop, undercoating, paint, etc. Very pleased with the results. I immediately had the whole car encased in epoxy primer (same day).

Brad,

Thanks for the feedback. I will try to track them down as well as look at some other media blasters in the area. Apparently blasting with dry ice is the new deal.

Brad Mackey wrote:

But the problem is not the acid/caustic leaking out. That would be a good thing. Rather it is the acid staying captured in the seams and crevices, being free to do its evil, dastardly, even vulgar deeds, unseen by the hapless owner. The damage would be effected in a matter of a few short months (all Februarys, I would imagine).

One advantage of the acid over blasting is that it does remove rust from areas that you can't get at via a blaster. But it does apparently require you to properly rinse the car. Also the acid is supposed to be something that will remove the rust, but not much metal.

Again if anyone knows of any local shops to check into or avoid, post here.

Brad Mackey · **Posted:** Sun Nov 20, 2005 3:13 pm

Richard Casto wrote:

Apparently blasting with dry ice is the new deal.

I used to sell that system, Alpheus, to the airlines when they were on a tear to reduce weight by removing all unnecessary paint on the fuselage. Sold a system after several expensive trials at Delta in ATL. They decided to use the system for environmental reasons, not cost. Just vacuum up the paint chips. It did a pretty good job of paint removal, but the process is SLOW going. We also sold a couple of units to companies that perform cleaning services on large boilers and Power Gen. fireboxes. It removed the crap inside pretty well, but again was time-consuming (read: EXPENSIVE). It never really caught on, and the sales expense was unacceptable to my company, so we dropped the line.

The system manufactures CO2 "pellets" about 3.0mm in diameter, extruded through a die so they come out looking like little barrels. These are fed down a tube at low pressure, and are injected into a 500-psi air jet at the spray nozzle. When they impact the work surface, they penetrate the paint skin and explode, causing pretty high localized pressures which ablate the surface of the work. Interesting concept, but used LOTS of energy in the form of very large compressors.

If the cost of the system eventually decreased, which it did not when I sold it, it may be at a level where consumer applications are possible. Otherwise it is probably to be found only in specialized industrial areas and may not be accessible to the masses. But, you never know...

Another system extensively used employs ground-up walnut shells. I think there are plenty of places that use it, as it is just considered another blast media. Again, not real agressive, and obviously fairly friendly to the environment.

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