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Hello mtbjeff, This is such a neat sight. If it was acid dipped, I would be interested in what you did exactly as my chassis is being dipped this week (google “carblast.de Facebook Montreal“ if anyone is interested). It would also be reassuring as it proves it can be dipped without damaging the factory tin in the lower corners of the windscreen which I was told is a small risk. Are you going to have it electro coated as well? Cheers, Christian
 

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Discussion Starter #4
Hello mtbjeff, This is such a neat sight. If it was acid dipped, I would be interested in what you did exactly as my chassis is being dipped this week (google “carblast.de Facebook Montreal“ if anyone is interested). It would also be reassuring as it proves it can be dipped without damaging the factory tin in the lower corners of the windscreen which I was told is a small risk. Are you going to have it electro coated as well? Cheers, Christian


Hi Christian, Yes it was acid dipped and I’m very happy with the results. I did remove the aluminum spacers in the front frame rails for the steering box and steering idler arm before the dip. I’m reinforcing both those locations and it aided in flushing out the inside of the frame rails.

I had no problems with the Tin welded locations on the car. Getting the body this clean has really helped in finding any flaws in the car, cracked seat mounts, rust repair or broken spot welds after 47 years.

I also dipped the Fuel tank and it is incredibly clean too. I’m really happy with the process.

The car was dipped at Metal Works in Eugene Oregon.

Jeff
 

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Wow ... still scares the heck out of me the concept of acid dipping your car, especially as these old cars were not (I believe) designed for dipping as more modern cars were so there would be drain holes, etc.

Yes, any updates?
Pete
 

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......especially as these old cars were not (I believe) designed for dipping as more modern cars were so there would be drain holes, etc....
Tha was probably true for the pre 1960's cars....but the Montreal, GT Junior and GTV's were definitely dipped. The large holes in the floor pan that are plugged with the rubber bungs are there for this very reason...drainage. As well there are openings in the lower flange of the sills that will allow liquids to drain out. The site below has photos of this and a nice little slideshow of other interesting Montreal photos.

Montreal Assembly | alfa-male


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Piece of art! I would be tempted to just steel wool the surface, clear coat it and hang it up on my living room wall!!!
 

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I am not sure these stripping baths are acid based I used to do a lot of paint stripping on furniture and metal years ago and I had a 7' by 5' by 4' tank full of caustic soda or sodium Hydroxide as it says on the label, it handled most paint well enough, old enamels and oil based, varnishes. The tough ones were water based and polyurethane types, I do remember once putting in an aluminium grill for too long it was partly dissolved when it I took it out! If someone knows what the acid is I'd like to know what it is.
Tim
 

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What were the cars being dipped in 20-30 years ago to get the paint off? As a guess is was caustic soda. When the paint comes off, the caustic soda (NaOH) interacts with the steel (Fe) under the paint and you get a thin Magnetite (Fe3O4) layer on your panel, which is black/blue in colour. Magnetite has a Mohs’ hardness level of 5.5 to 6.6 and the only way you can get that black Magnetite later off is to use something that has a higher hardness!
 

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Steve is the usage of an acidic neutralizer the answer after the dipping process? I used to use acetic acid otherwise know as Vinegar on the gear that was dipped in the stripping tank, it was first thoroughly pressure washed with water then sprayed with vinegar.
Tim
 

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Acid dipping may be fine. My personal concern would be in the areas the acid has reached (any boxed sections, i.e. rocker panels, A Pillar, B Pillar, etc.) that you cannot get the neutralizing solution into with spraying. It would almost having to dip the car in a acidic neutralizer tank after the acid dipping...
 

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The car I purchased was sitting in 'black primer' for the last 20 years . When it came time to get rid of what I thought was black primer I was wrong, it was magnetite.
I did send the car to have it lightly blasted to get the black layer off. It could be the magnetite was too hard for the aluminum oxide or garnet abrasive which just bounced off the magnetite film, then the etch primer over the top the magnetite well some one forgot to tell me the black layer did not come off !, they just put lots of grey etch primer which was also very hard as well. I had the car sitting inside garage for about 2 years. then took it to the panel shop. The magnetite layer was still there under the grey etch primer I just did not know it, so not only the etched primer would not come off neither did the black film (magnetite) double trouble.
I just had to work it out as quickly as possible overnight as my panel/paint guys were upset as it was taking too long to prepare!
The simple job became complicated and more costly. I remembered some one said to me it was dipped before. The only black film/coating possible on mild steel was to have it dipped or in caustic soda (Sodium hydroxide). I don't think caustic = acid, Caustic soda = alkaline. This was the same technique they used back in the old days when they did not have access to high quality harden steels for gun barrels. That is why early gun barrels are blackish /blue. In one chemical article they talk about 'magnetite films produced on the mild steel surface could prevent or minimize the corrosion on its surface' which in effect what happened to my car as it had no paint on it for 20 years. Only problem is magnetite has a slippery structure so some paints primer / filler will not stick to it so compromising the job. Unless you like the black magnetite look.

I don't know all the details, but logic tells me if you leave painted steel (car or parts) in caustic soda NAOH and it works faster than you expect thus giving more time for the steel to be exposed you will get a thicker film layer of Magnetite, making it harder for you to get it off latter. We had to use Zirconium 3M sanding discs which got us mostly there.
 

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Steve is the usage of an acidic neutralizer the answer after the dipping process? I used to use acetic acid otherwise know as Vinegar on the gear that was dipped in the stripping tank, it was first thoroughly pressure washed with water then sprayed with vinegar.
Tim
Not sure you may be talking about HCL Hydrochloric acid which I don't know much about except I don't like for use in rust removal. I prefer Molasas solution for rust removal as they used back in the old days, but it can get stinky and stains your hands.
 

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Love the detail the pictures show between chassis construction.
 

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Just to be clear about my experience using caustic soda for paint stripping in a big steel tank, after the items had been left in the tank for about 6 hours depending on how many coats of paint had to be removed, the items were then removed from the tank and pressure washed down with water, they were then given the vinegar treatment( acetic acid) to neutralize the caustic soda residues. Some folks use a heated tank that speed up the process significantly.
Tim
Tim
 

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Discussion Starter #18
The body did go through a neutralizing tank after being dipped, Holes were drilled into key locations of frame rails and the body before dipping to remove air pockets and allow draining and flushing after. The body also gets a phosphoric acid wash at the very end for metal conditioning. The body remained unpainted for two mouths while it had over a 100 hours of metal work performed before painting any primer on it. It showed no signs of leching acid or rusting during this time. The Phosphoric metal conditioner is excellent at reducing flash rust.

The Body and Paint restoration work is being done by Adam Johnson. He has handled body restorations on more classics cars then anyone I know from 275 Ferrari's, Dusenberg and 917 Porsche's. Adam was the paint shop manager at Canepa Design for 15 years before opening his own restoration shop in Watsonville CA last year.
 

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Discussion Starter #19
A few updated photos of my 1971 Montreal project after primer
 

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That is dead sexy even in primer. Interesting topic with the dipping, I'm doing a Lancia Scorpion restomod and was wondering which direction to go with the bodywork derusting.
 
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