1962 Cadillac (1 Viewer)

[J Mack]

My friend @bobm likes to keep track of the shenanigans in my shop so I'm going to post some updates on this little Cadillac project here.

I bought this car on BAT last year.. https://bringatrailer.com/listing/1962-cadillac-62-convertible-19/
And now I'm going to attempt to get everything working and looking like new on a car that hasn't moved in 52+ years.

Checking everything over and firing it up for the first time.

I got three of the four brakes working good enough to Back it out of the shop, I believe this is the first time it's moved under its own power in 50+ years.

 

[J Mack]

Car is back in the shop now and I have a few things to do before I pull the engine and transmission to rebuild them.
First I need to see if this rear window can be saved and if not get one on order.

I'll update after the rest of the stuff gets here to bring it back to life.

 

[open country]

Sweet project, and looks like a great buy from the listing.

 

[J Mack]

Sweet project, and looks like a great buy from the listing.

Thank you!
I wasn't serious about buying another project car 2100 miles away so I kind of threw a "I don't care if I win" bid at it and thought if I get it for that price I'll figure it out later then went back to work and forgot all about it until I got the E-mail saying I won.
It's a cool car and I'm looking forward to seeing it back on the road.

 

[bobm]

My friend @bobm likes to keep track of the shenanigans in my shop so I'm going to post some updates on this little Cadillac project here.

I bought this car on BAT last year.. https://bringatrailer.com/listing/1962-cadillac-62-convertible-19/
And now I'm going to attempt to get everything working and looking like new on a car that hasn't moved in 52+ years.

View attachment 3574398
I got three of the four brakes working good enough to Back it out of the shop, I believe this is the first time it's moved under its own power in 50+ years.

Only had 3 brakes in Blue when we drove to Rico

 

[bobm]

that body style

 

[bobm]

What dat Caddilac have for engine? Whats the plan on this 1. Chebby has a nice stance it's coming out Great

 

[WarDamnEagle]

What dat Caddilac have for engine? Whats the plan on this 1. Chebby has a nice stance it's coming out Great

390 Bob according to the BAT listing.

What a great project car. Super cool.

 

[J Mack]

What dat Caddilac have for engine? Whats the plan on this 1. Chebby has a nice stance it's coming out Great

Thanks Bob, Chebby is at the upholstery shop.

I rebuilt the hydraulic pump for the top and it goes up and down now..

Magic leather conditioner according to my upholstery guy will make the leather like new again.

 

[Ol Yeller]

Look Squirrel!

Seriously though, another nice project, thanks for sharing J, in for the ride.

 

[J Mack]

Look Squirrel!

I have six project vehicles and a very understanding bride going right now.

Just a little more to go on her Pickup then full speed ahead on the Cadillac and the little T race car.

 

[bobm]

Almost forgot about the "T" !!!

 

[J Mack]

UV light and hydrogen peroxide gel, we'll see in the morning if this lightens the rear window.

 

[BILT4ME]

UV light and hydrogen peroxide gel, we'll see in the morning if this lightens the rear window.View attachment 3575906
View attachment 3575907

So, did it fix it or ruin it?

I was going to suggest a heat gun, but I've never done it before.

 

[WarDamnEagle]

UV light and hydrogen peroxide gel, we'll see in the morning if this lightens the rear window.View attachment 3575906
View attachment 3575907

Did your dentist recommend that procedure?

 

[J Mack]

So, did it fix it or ruin it?

Definitely lighten it but not as much as I hoped.

Going to add some sodium carbonate to the mix and try again tomorrow.

 

[WarDamnEagle]

I wonder if Novus plastic polish would help? There's 3 different ones; you might try the least aggressive and see what it does if all else fails.

 

[J Mack]

you might try the least aggressive and see what it does if all else fails.

I polished this window inside and out to get it transparent again, if you go up to the photo when I backed it out of the shop for the first time it looks like a piece of cardboard in there, a completely brown opaque rear window. I was asking my upholstery guy about replacing this for me and he said he’s had some success with polishing and if I could save the factory plastic it would add value to this survivor.

The polishing went really well and exceeded all my expectations but it still has a slight brown/yellow tint that I’m trying to lighten. When looking up “How to lighten yellow plastic” I found a bunch of information on the process called "retr0bright" that the nerds use restore old “retro” computers and game consoles. Some info here: Retrobright - Wikipedia - https://en.wikipedia.org/wiki/Retrobright

If you have followed any of my other builds you’ll know I’m not a stock resto guy and all this seems like a giant waste of time and money that could be better spent cutting the springs out of this car and adding air bags but I’ve had several people approach me and advise to keep this car as original as possible and rebuild vs replace everything that’s not functioning. This car is a time capsule and with the exception of the radiator and fuel tank that were gone by the time I bought this car it still has everything it left the factory with in 1962 so for now I’m going to do my best to restore all these parts and get this car running and looking good.

 

[J Mack]

More reading if anyone is interested in the process.​

​

Retrobright: Complicated Chemistry - An Educated Opinion​

It's a lazy Sunday here and I decided to take on the task of reading up on Retrobright chemistry and figure out if it's really worth it. I have a raised eyebrow on the peroxide formulas for the Retrobright process. Since my PhD thesis involves radical chemistry, and I have some experience specifically in peroxide industrial use and production in UV-Protection coatings, I figured I can give an educated opinion on the process.
First, I want to link this PDF to a Hack-a-day post on the process. The author claims to have had a conversation with James Pickett, a PhD in Polymer Chemistry on the finer details of plastic yellowing & Retrobright. The chemistry is correct throughout, albeit surface level. I won't rehash any statements made in the PDF and encourage readers to glance over the linked file.
Now, I will have some definitions to educate readers on some chemical terms that will be used in this post. A Radical is a molecule with a single, unpaired electron. In the attached image is an *OH radical, the main species in hydrogen peroxide (HOOH) that is involved in chemistry. The yellow mesh is the simulated volume that the unpaired electron occupies around the Oxygen atom on a ball-and-stick model. When UV light hits a molecule of peroxide, it Initiates homolysis; 'cutting' a peroxide in half to form two *OH radicals. This chemistry is not unique to peroxides, and can be found in other X-Y single bonds. An Anion is a a molecule with a pair of electrons and has a formal negative charge. In the attached image is -OH (hydroxide) anion. The electrons occupy the same volume as the radical *OH, but this time has a phasing (arbitrarily colored Red and Blue in the image.) From a 1000 ft view, while the atoms in both *OH and -OH are the same, chemically, they are very different and *OH is far more reactive.
The main form of retrobright is an oxidation bleaching. This is the use of some potent oxidizer to break down triple and double bonds into single bonds while adding some functional group. The above linked PDF claims that the conjugated double bonds (responsible for the yellow color of degraded plastic) can be revered by adding OH groups (and halogens such as Chlorine in the PDF's example from Master Organic Chemistry). This is not the only way to oxidativly bleach, but what we're interested in.
The paper on the production of using tetraacetylethylenediamine (TAED) and HOOH to produce a bleaching agent peracetic acid (PAA) is found here and here. They cite an earlier paper from 1974 in use of a paired electron process (read Anionic) to form -OH and -OOH from hydrogen peroxide and peracetic acid (although A. Laurent & N. Pellissier research Cope and Claisen rearrangements & pyrroles - not plastics). On first glance, D. Davis & M. Deary perform a kinetics experiment on the formation of peracetic acid and its reactants; taking frequent aliquots. They report that the maximum transformation of TAED to PAA happens at about 1 hour, and then the concentration becomes linear afterwards. The takeaway being that the additive TAED does not take full effect until 1 hour after mixing, but doesn't get any stronger the longer it sits. The reaction also forms anions and not radicals (remember; very chemically different), but the paper was published in 1991. Radical chemistry is far more understood now three decades later.
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To get into the meat of the chemistry, the retrobright procedure involves these ingredients per the Wikipedia page:

• Hydrogen Peroxide Solution (30% is consumer-grade concentration)
• TAED (1mL per 3L of solution)
• UV light (380 nm is your textbook sweet-spot wavelength)
• Xanthan Gum/ Arrowroot for a thickening paste (this is just cellulose basically, save money by buying corn starch)

UV light is the propagater in the formation of radical species. It is what will break down hydrogen peroxide and PAA to its respective radical species. These radical species will then break down the conjugated plastics; bleaching it. TAED, from the 1991 paper, forms PAA in a paired electron process, forming anionic species. This means that by including TAED, you would have now two competing chemical processes: UV-initiated radical chemistry and peroxide initiated, paired electron chemistry.
If we're comparing the production of an acetic radical from PAA, the enthalpy of homolysis is ~45 kcal/mol. The enthalpy of homolysis of the *OH radical from hydrogen peroxide is ~56 kcal/mol. (enthalpy of homolysis is calculated using Hess's Law.) I propose that the PAA would be forming radical species in concurrence with the paired electron species (argumenative to the 1991 paper) and that the production is 10 kcal/mol more favorable than hydrogen peroxide homolysis. Having said that, the amount of TAED added per volume of solution is minuscule ( 0.03% v/v). When it comes to industrial scale peroxide addition to catalyze reactions, you generally add ~1-2% mol/mol. This means that if you followed the above recipe, even though that the TAED would be a favorable addition, it's literally a drop in the bucket on any meaningful chemistry. Increasing the amount of TAED would be favorable, and decrease the time you would need to have a part sit in the irradiation bucket. Alternatively, if we're only concerned about making radical species and breaking down double bonds as cheaply as possible, then forgo the addition of TAED and let the plastic soak longer. A negative side effect is that radicals are not selective to react to only double bonds. They will react with anything piratically. By increasing TAED in a meaningful amount of mass, you could end up with a case where the radicals produced work too good and end up degrading the plastic further. Someone needs to perform experiments on this and see if this is a possibility.
The addition of a coagulant to make a paste is okay in theory, but from an ease of process standpoint, I'd just use the peroxide bucket and UV light setup.
It should also be stated that this process is not permanent, and will eventually return to yellow over the years as the plastic is exposed to oxygen. You'd reform conjugated plastics or entirely break down the polymer bonds, making the plastic brittle and chip.
To circumvent that, I propose one should add a UV coating on top of a brighted shell. I'd recommend benzophenones as the main ingredient we should be looking for. Benzophenone-6 ( 2,2'-Dihydroxy-4,4'-dimethoxybenzophenone) has a max UV-absorbance at 340 nm, our magic radical initiating wavelength, with high absorbance as well in 280 nm. It's also safe to the touch. Unfortunately, in concentrated layers it will give a slight yellow tinge. This should prevent further UV damage in the plastic.
Other notes:
Sodium Percarbonate is just an anhydrous form of Hydrogen Peroxide. You might be able to make a more concentrated solution of hydrogen peroxide using sodium percarbonate, but I don't know why you'd want to.
Potassium Permaganate (KMnO4) can also be used as a bleaching agent, but might be more expensive than 30% hydrogen peroxide based on your location.
All calculations were performed on Spartan '20 using the w-B97X-D/6-31G* for geometry and energy calculations. (If any other Quantum Chemist reads this, I was too lazy to increase my basis set for a post on r/Gameboy)
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tl;dr: Retrobright doesn't fix plastic, only oxidizes the outside layer. Adding TAED doesn't hurt, but the current recipe is functionally probably insignificant. A benzophenone UV coating might be our best bet for further UV protection.
EDIT: Minor proofreading


Link:

 

[1911]

Potassium Permaganate (KMnO4) can also be used as a bleaching agent, but might be more expensive than 30% hydrogen peroxide based on your location.

Trivia (delete this post from your thread is desired):

It's really easy to precipitate nice orthorhombic Potassium Permanganate crystals out of a saturated solution; a good school exercise for almost any grade as an introduction to crystallography/mineralogy.

Another interesting property of it as a strong oxidizing agent, is that it will spontaneously ignite when combined with almost any glycerol compound, including car anti-freeze and glycerin used in soap and skin-care products. Growing up, a friend and I used to make our own flare bombs that way and terrorize passing motorists by mixing the components in a small container in the middle of the road as a car was approaching, and using the several seconds of delay before combustion to hide nearby and observe. Fortunately, we never caught anyone's car on fire.