"Acid (or Chemical) Dipping"--what's The Hive's position?

Is this cost effective for a non-full restoration?  It appears to me to be hellishly expensive but probably very effective... 

How do you locate a reputable shop in your area?  Contact your local restoration specialists?

I've never had a whole body dipped. I'm sure there will be residual chemicals trapped in pinch welds and whatnot that will cause problems later.

We've had plenty of cars media blasted with good results. 

I am 100% on team dip.

We are lucky enough to have Metalworks just a few miles away from the shop

The only time we do not have a body dipped is when we cannot, IE when there is aluminum or fiberglass bonded in a way that is not removable. The firewall and floors in a Ferrari 250/330 is a good example. I will regularly pull the alloy skins off of a chassis to send them to be dipped. I have a Maserati Mistral, Abarth Record Monza and an AC Aceca in such a state right now.

The major benefit is that all the rust you cannot see inside pockets and chassis rails is removed and neutralized.  In some cars you will need to drill holes in the chassis prior to dipping, but if you are dipping you are planning metal repair anyway.  Austin Healey BN/BJ series cars need a few holes in each rail. The last dip is a rust inhibitor. I know from experience that if not scuffed it will last 4 years in a drafty outbuilding with no signs of flash rusting.

Sandblasting is messy and only gets the rust within line of sight. You will have to cut open rockers and rails to 1 deal with the rust still inside and 2 get the sand out.

Every car we get in that was restored in the last 25 years has sand everywhere inside of it. We removed four full 5 gallon buckets of damp dirty sand from a Lancia B20 Aurelia. That sand trapped in the rockers and inner pockets caused a lot of rust damage.

I have had low crown panels warped by sandblasting and even soda blasting. We now have a local company offering dry ice blasting but it is more of a detail service and not for stripping to bare metal.

Nat (whom I have the ultimate in respect for) over at Retropower has his own opinions on this subject which are very much the opposite of mine Video here but I do not believe he has any experience with the process Metalworks offers as I have experienced none of what his perceived drawbacks would be.

Take a look at this Fiat 500 after the outer panels were cut off and see just how clean everything is in areas that would never be touched by sandblasting

I've had my bonneville in three different cities as I worked on it.  In all three of those cities (Harrisburg PA, Los Angeles, and Austin TX) I sought out dipping services.  Every time I was told by the dippers that they don't want my money.  They encouraged me to soda blast instead.  I was puzzled.

It seems like no matter how much you rinse, the seams all hold onto some of the acids and they will always be a source of paint bubbling, corrosion, and problems.

Having said that, it means I have no actual experience with dipping so I can't really talk intelligently about it.  I had it blasted and I'm happy with the results.  I'm interested to hear more from the pro-dipping sector.  I'm curious to know if I made the right choice.

In reply to Trent :

Let me second your statement.  Every restoration I've done is acid dipped.  I take the required precautions prior to paint and have never had a single issue.  
 My first car was acid dipped back in 1973  and to today the original lacquer paint is still very nice.  In spite of decades of use and racing.   
 

All of the restoration work done over at Classic Motorsports has been blasted and not dipped. (In fact, our painter won't take cars that have been dipped.)

I did it with the first restoration I ever did.

Lets just say that there is nothing that an inexperienced consumer and an indifferent supplier cant screw up for a lot of $$$.

Yes, it stripped the shell to bare metal. It was returned in an oily coating that I was told to wash off with bleach when it was time to prime the shell. Here is a question: In what universe is it a good idea to wash a bare metal body?

I found that in some of the folded seams there was still some chemistry going on. Some primer reactions did happen but with 8 years of working on the car before paint, it was a simple matter of refinishing where problem spots showed up.;

I did not end up re-using any of the closed frame sections that came from the factory. But the ones I looked into as I was cutting them out were all fuzzy brown inside with flash rust. Had I not replaced these parts I dont know how long if ever before they became an issue.

Where I am a HUGE fan of chemical stripping is for all the buckets and boxes of parts that go ON the shell. So nuts, bolts, fenders, brackets and suchforth. They look like new and can be either sent for plating or epoxy coated after a good soak in gunwash.

I have first hand experience with a ruined body shell  from sandblasting in the form of the Molvo. See my above statement for what happened there with the original owner/ restorer. Took 400 hours to smooth it out. On the other hand, I have had a lot of luck sending people to a local sanblaster who seems to know what he is doing. He runs an industrial blasting business and personally does the old car thing as a side gig. I cant afford him, but those I send seem happy with results and price. 

So there is no clear answer. An experienced restoration shop working with an involved supplier is going to be the best result.

This is interesting. Being that Metalworks is the only one providing this service in this area I don't have experience with anyone else. The actual material removal is done more with heat than anything else. 2 days in a 200 degree bath. There is no oil at any time, the car is dipped in a neutralizing solution afterwards, there are several stages of intense pressure washing during and after the process, the anticorrosion coating is dry. 

Frankly it is the only way we can be comfortable giving a warranty on our paint jobs. 

Unfortunately the wait list at Metalworks is getting longer and longer thanks in part to a certain Utah based shop that rhymes with Shindig with a TV show sending all their projects to them.