Problems Stripping to Bare Metal

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PostPosted: Fri Mar 18, 2022 2:09 pm
I'm working to recondition my 1996 Thunderbird and would like some advice. I've already read hundreds of posts on this forum (and others, too) but I've run into some issues that I am not qualified to explain on my own, since I've never done any body work or paint before.

I am the original owner but stopped driving the car more than 10 years ago. I left it outside without any care at all, so the paint is now shot. I'm not trying to make it a show car, I just want it to look good enough to not be an embarrassment. Some areas just need new clearcoat, but some areas have basecoat damage, and some (the roof, in particular) have surface rust. It's the roof that is causing me the most trouble at the moment.

Stripping the roof down to bare metal has been more difficult than I expected... and having no prior experience, I have no idea whether my expectations are just unreasonable, or if I am doing something wrong. It would be great to have someone come over and look at what I am doing to let me know, but since I can't do that, I thought maybe I could upload some pictures, tell you what I've done, and ask you folks what you think.

PhotoA1a.jpg
basecoat damage


The photo above is an example of some of the non-rust damage on the roof... white marks in the black paint. FYI, the lower area in the photo is after scuffing with a scotch-brite pad (which did nothing to the marks), and the upper area in the photo is after sanding (by hand) which enlarged the marks. From there I concluded the marks were the primer showing through damaged basecoat, so I have removed (most of) the basecoat using (I think) P400 (wet, I think) on a sanding block. (I say I "think" because I tried a lot of different things on different parts of the car, and they are all starting to blur.) Anyway, removing the basecoat wasn't a problem.

PhotoA2a.jpg
rust damage 1

PhotoA3a.jpg
rust damage 2


The two photos just above are examples of rust damage that became visible in some areas after the basecoat was removed. As I stated, some areas of the roof had visible rust even before the basecoat was removed, but this is an area where rust was not visible until the basecoat was removed. My conclusion from this is that I should strip the entire roof back to bare metal in order to eliminate all possible rust... but this is where I have run into a problem.

The problem is that removing the primer (I assume that is what the grey layer is) has proven to be difficult. By "difficult" I guess I mean it isn't happening fast enough to my liking. Of course, as I said, I've never done this so maybe I'm just being unreasonable?

PhotoA4a.jpg
bare metal


For example, to remove a 2" by 15" section of paint (see Photo just above) with an electric DA Sander/Polisher and 80 grit sandpaper took me at least 30 minutes (including breaks to check the work, rest my arms, change the sandpaper, etc.)... Is that normal? Could I just have an unusually hard primer? I also tried chemical stripping a section, but both strippers I tried (Aircraft Remover and Kleen-Strip) did absolutely nothing! Are those not good products, or again, could my primer be something special?

BTW, if you look closely at that last photo, you can see a yellowish-grey colored area (most visible at the lower right of the exposed area) that appears to be below the grey primer... what is that??? There's a better view of it in the next photo (below) which is of the top of the rear quarter panel where the trunk lid (top right) and rear window (top left) meet. Everywhere I've sanded down to bare metal there is this yellowish-grey coating just below the primer, but nothing I've read anywhere mentions anything like that, so either I've got a different paint job than most people or I just don't know what I'm doing... which is it???

PhotoB1a.jpg
below the primer


Finally, given my difficulty stripping the paint with a DA and chemicals, I'm considering trying media blasting, but am worried about where all the spent media goes (after bouncing off my car's roof in my driveway) and also about whether the roof can withstand the effort (it already has areas that "oil can" when pressed, which may or may not mean anything, but I don't know since I am new to this). How do I decide whether blasting is okay or not?

Well, that's my story, and if I am just showing my stupidity then I'm okay with that... and I hope you all are too. Either way, I'd love to hear what you experts think I should do (short of taking the car to someone else <grin>).

Thanks!

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PostPosted: Fri Mar 18, 2022 5:10 pm
Media blasting is hot and dirty work but very rewarding.
Be sure to use the proper grit and crushed glass works excellent.
I did my 1968 GTX in the garage but you can also put plastic sheeting down and then collect and reuse the media. I have a funnel with a screen in it to get the junk out.

The trick is to keep the air pressure low but still enough to be effective. You also don't want to spray directly at the panel but with a slight angle. I have never had any panel warp doing it this way.

This shows the factory paint being stripped off:
Engine Compartment Left.JPG


I started at the front and worked my way back:
Media Blasting Progress 1.JPG


Here you can see where filler was uncovered:
Quarter Panel Right Stripped.JPG


Media blast removes the filler as well but takes longer if it's deep.

Once it is done, you can clean it and shoot epoxy primer or if you prefer go over the metal with 80 grit on a DA. Shown here:
DA 80 Grit over blasted metal.JPG


Here's the engine compartment in two coats of black epoxy:
Engine Compartment Epoxy.JPG
1968 Coronet R/T


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PostPosted: Sat Mar 19, 2022 11:17 am
do you have a fairly large air compressor?
Jay D.
they say my name is Jay

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PostPosted: Sat Mar 19, 2022 8:06 pm
Thanks for the replies...

I've seen other posts here about media blasting and there's no doubt in my mind that those results look awesome... I'm just worried mine won't because I have no experience in that (compared to sanding, which at least I've done before, including some small automotive stuff, like a roof rack). So I'm still reluctant... But I'll think some more on it.

Jay, I do not have a large compressor, only a small one. Not that I couldn't buy one, if it was justified. Why do you ask?

Thanks,



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PostPosted: Sat Mar 19, 2022 8:41 pm
you could use air tools, air sander and you'll need one to, paint with. get some 36 and 80 grit 8" discs and a foam interface pad you can use a 9227C Makita angle sander its variable speed good for sanding and buffing. with the 36 grit and the Makita sander you should be able to strip that car 2-3 hours. the black rubber abrasive wheels work good also, IF you can find them in 8", 7" is easy to get .
Jay D.
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PostPosted: Sat Mar 19, 2022 9:03 pm
96EbonyBird wrote:Thanks for the replies...

I've seen other posts here about media blasting and there's no doubt in my mind that those results look awesome... I'm just worried mine won't because I have no experience in that (compared to sanding, which at least I've done before, including some small automotive stuff, like a roof rack). So I'm still reluctant... But I'll think some more on it.

Jay, I do not have a large compressor, only a small one. Not that I couldn't buy one, if it was justified. Why do you ask?

Thanks,


You would definitely need a good compressor, say 5-7 hp, 2 stage with an 80 gallon tank that puts out 15 CFM or more to do any serious blasting, use air tools or a quality spray gun.

I have also used a heat gun and razor blade (in scraper handle) to strip paint. Personally, I find media blasting and the razor blade to work much faster than sanding to strip paint, especially when doing a complete.
1968 Coronet R/T


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PostPosted: Sun Mar 20, 2022 10:41 am
Coronet is right, even if you could get MC stripper it would not do a thing for your pitted rust. You can treat that rust with chemicals after sanding, but your way better off blasting. You can pay to have a mobile service to blast it at your home soda or hydro.. Here's the deal though, you need a proper a/c, not just for sanders and blasters but also for painting, if you intend to paint it on your own. Lastly, if you can’t take the time to get it stripped and epoxied in a two day period... Do it one section at a time blast, seal and repeat.



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PostPosted: Mon Mar 21, 2022 4:47 am
96EbonyBird wrote: I'm just worried mine won't because I have no experience in that (compared to sanding, which at least I've done before, including some small automotive stuff, like a roof rack). So I'm still reluctant... But I'll think some more on it.

,


go to your local boneyard and find a hood or other body part that resembles the finish on your roof to practice on.

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PostPosted: Mon Mar 21, 2022 12:47 pm
you could use air tools, air sander


Okay, I didn't think an air sander would be significantly better than an electric, but I'll look into that some more...

you can use a 9227C Makita angle sander its variable speed good for sanding and buffing


Isn't that an electric model? If so, I'm already using something similar (a 6" variable speed DA sander/buffer model that spins up to 6500 RPM) so shouldn't mine work as well or better as that one? Again, I'm no expert on this stuff, so if I'm missing something please let me know.

with the 36 grit and the Makita sander you should be able to strip that car 2-3 hours


I did consider trying 36 grit paper on my DA but was worried that could damage the underlying sheet metal... am I being too cautious?

You can pay to have a mobile service to blast it at your home soda or hydro


Wow, Rsrguy3, I never thought of that, but a quick google search found multiple companies in my area (So Cal) that do it... I'll look into that!

Thanks all!



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PostPosted: Mon Mar 21, 2022 1:24 pm
I've used 40 grit to strip paint off of metal before nice and quick.

You're not going to sand the metal much. Just trying to get the paint pulled off most of the way. Then come back with 60/80 to finish up.
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