For the last three months I have been working numerous hours to clean up the undercarriage of my low mileage, all original 1974 Coupe deVille. As you can see here on my website and in this image gallery.
As I had put so much effort in totally de-rusting the underbody of this low mileage car, I decided to let a professional body shop re-paint the bare metal frame, suspension parts and floor pans this time. My goal was to have the ultimate quality paint job in the factory correct colors underneath the car. I´m not very good in painting and my attempts often result in runnings, which I have to sand out and other imperfections I wanted to avoid.
So I handed the de-rusted car over to the paint shop.

BACK FROM THE PAINT SHOP
When I got the car back, everything looked o.k. as you can see on the pictures below. I was not too impressed by the work they did, as there were quite a few imperfections and some sloppy paint work visible, if you looked very closely. At this point I was already worried that they maybe did some shortcuts before painting, when they should have properly cleaned the bare metal, before they sprayed the primer.
They used some high quality epoxy primer and 2k paint for the job though.

THE MESSED UP ENGINE BAY - OVERSPRAY HELL
There was a terrible mishap at the shop, as they did not mask off the engine bay properly, so all the paint dust and overspray collected inside of the engine bay, and the entire engine bay looked like somebody emptied a spray can into the engine compartment from about 5 feet away. Everything was covered with paint overspray.
I was so shocked when I opened the hood that I almost passed out. The once perfectly clean, all original engine bay was a total mess. It looked so terrible that I could not even snap a picture. Last year I had spent weeks to clean it to my standards…
I had no idea how I could remove the overspray without damaging the original finish of the engine, rubber hoses, cables, wires, accessories and engine parts. This was a terrible situation for me.

REMOVING OVERSPRAY WITH CLAY
I then remembered that detailing clay can be used to remove overspray from paint, but I was not sure if it would work with this heavy amount of overspray. The paint shop gave me a special clay towel to clean up the engine bay, which works like detailing clay, but can be cleaned more often and is easier to use and more aggressive. This thing really works well, but I had to do so much scrubbing on some parts, that some painted areas, like the wheel wells or the air filter housing, turned a little dull after this tiring work. To get them shiny again, I had to hand polish each and every part after claying it. It took me about 25 hours to remove all the accessible overspray from inside the engine bay. I had to thoroughly scrub each and every part, wires and hoses with the clay towel and all purpose cleaner as a lubricant. The areas which I could not clean good enough by hand will be cleaned with dry ice soon. I´m 100% confident that it will look as good again as it did before this happened - I have already achieved 90%, the rest will get perfect again with some dry ice cleaning…

TIME FOR UNDERCOATING
My plan is to protect the undercarriage with a transparent undercoating, which is as good as invisible if properly applied. It will provide a perfect protective shield against road debris, stones and is rust prohibitive. This high-tech material is far superior than the original tar based undercoating which is normally used, and as an additional bonus you can always see what is going on underneath the undercoating. I decided to use a product from a german company called "Timemax USB Clear". Timemax is one of the leading specialists for rust protection, and their products have won some independent tests, done by classic car magazines.

THE PAINT DOES NOT STICK!
Before spraying on the undercoating, I had to mask off the areas like the frame, drive shaft, axle, suspension parts, fuel tank, brake lines, hoses and brakes. After a day of masking off all the areas, I discovered a small paint chip on the frame. When I inspected it with my fingernail, a bigger chunk of paint flaked off the frame. I then used a scraper to scrape the paint, to see if it was just a small area where the paint would not stick properly. The area where the paint came off got bigger and bigger, and soon it became clear that the paint does not stick properly anywhere…
Of course this was another big shock for me, as this meant that 3 months of work were completely destroyed… When I inspected the areas underneath the removed paint, it quickly became clear that the paint shop did not treat and clean the bare metal before painting, as they should have done. They just did a quick wipe with silicone remover.
Of course the bare metal underneath a 41 year old car is full of oil and grease and needs a lot of cleaning with strong chemicals before paint will adhere to it. Unfortunately they skipped this most important step. Although I brushed away all the rust and everything looked shiny, the oil and grease is in all the pores of the metal.

I HAVE TO START ALL OVER AGAIN - REMOVING THE FRESH PAINT AGAIN
This now means that ALL the paint they sprayed on has to come off once again. Also the brown paint on the floor pans has to be stripped again as well.
I asked a dry ice cleaner to try if it can be removed with his method, and it soon became clear that it is possible, but will take at least one full working day, and this will cost a small fortune.
There will probably be some areas left which I will have to rework by hand.
As you can imagine, this is a huge step back for me. I worked so hard and so many hours, often till late into the night, to finish this project for nothing …
The paint shop knows that they did a lousy job and is very supportive to resolve this issue.

This video shows how badly the paint sticks to some of the frame parts. It can be blown off with the pressurized air on some areas…

WHAT´S NEXT?
Before dry ice blasting the undercarriage once again, we will try to get the paint off with a powerful high pressure washer. Once the paint is gone again, we will clean the bare metal multiple times with acetone, marine clean, a special metal cleaner and metal prep. We will also sand everything with some coarse sandpaper to get a little rougher surface to make sure that the paint adheres much better next time.
I also want to go for a black with less gloss, as it was too glossy and did not look correct.

I hope that the weather will be good enough in January 2016, so that I can start all over again. At the moment I do not have the motivation to do anything on the car, and I do not even want to look at it, as it hurts too much. I still have to recover from the things that have happened. This is so frustrating. I hope that it will look like it should after the second attempt.



The 3 stages of the project so far.

Everything looked o.k. after painting, but the paint does not stick to the metal due to poor cleaning by the paint shop.

This is the transparent undercoating I wanted to apply when I found out that the entire paint on the undercarriage does not stick…

Unfortunately the paint does not stick to the bare metal… I could scrape it of with a simple scraper. You can see all the flaking paint on the floor…
The paint is peeling off in big chunks…

So ALL the new paint has to come off again. Here the dry ice blaster is trying if it can be removed with dry ice cleaning.

BE CAREFUL WITH ZINC PLATED PARTS AND RUST REMOVAL SOLUTIONS
Due to all the problems I had, I completely forgot about some fasteners from the rubber splash guards, which I had soaked in the rust remover solution for more than a week. This long time in the liquid removed all the surface rust, but the acid also ate away the zinc plating. So whenever you try to remove the rust from anodized fasteners and screws, make sure not to soak them for too long.
As I can´t get the fasteners and screws very easily here in Austria, I had to brush away the remnants of the zinc coating with a wire brush, and then painted everything with Eastwoods Silver Cad paint. This does not look 100% correct of course, but will have to do until I find some original replacement hardware. Besides a few washers, these fasteners won´t be visible anyway.

I forgot some of the fasteners for the rubber splash guards in the rust dissolver solution. It ate away the zinc plating. So I had to remove the remains of the zinc plating with a wire brush.

The cleaned fasteners. I spray painted them afterwards with Eastwood zinc paint.

Tags:1974 Cadillac Coupe DeVille, 1974 Cadillac Repair Tip, Restoration, Overspray, Clay Towel, Video, Removing Overspray, Undercarriage, Underbody, Rust removal, Paint