Help: Cleaning Old Metal Body

Markus Kutsch The Plastic Bench
Hi Mate...perhaps this may help...or you get some Info to solve your problem on this page.

Cortex
Thanks! I will look for the problem there.

Robert W Martel
Hi Cortex,
It looks pretty "rough" to me.
Actually I used to have one of these kits, don't remember quite why I sold it. I think the windshield frame was broken. Anyway,,,,,
This is what we refer to as "die cast" metal, us old timers called it "pot metal", another name is "white metal'. You see a lot of aircraft landing gear legs called "white metal" The "Die Cast" cars you buy are pretty much the same metal,,, painted.
The metal is basically an alloy of zinc with small quantities of aluminum and copper. some older metals had lead, tin and other misc. alloys. Depending on the manufacturer they have changed some over the years, but is still relatively the same stuff.
The discoloration & pitting you are seeing is basically as you would say "Rust". Although Rust is referred to in Iron, Steel, or Tin. It is "oxidation" of the metal due to it's reaction to air, moisture, whatever it is exposed to over the years. Most metals Oxidize.
If I remember these "Die cast" car kits didn't look that great when they were "New", and did need to be prepped well before painting.
I'm not sure there's a chemical that will remove the discoloration, you might try Vinegar! Any body else out there might know of something.
Basically you need to treat it like any other metal you are going to paint. Remove any loose scaley, crusty crud !! A good stiff wire brush or sandpaper. I wouldn't start with anything too course unless you absolutely have to,,, say 320, 400 grit and work your way up to say at least 600.
You'll need to get or make an assortment of sanding sticks/blocks. You want hard sticks to smooth the surface,,, don't just use your fingers. What looks smooth to you now won't look so good under a coat of glossy paint,,,, trust me a good gloss coat will show every defect !!
If you have some bad pits you may have to start coarser. You will probably need to use some putty or body filler for bad spots. Then you'll need to put on some good coats of filler primer. I'm not sure the brands,,, many recommend Mr. Surfacer or Tamiya or even Automotive spray primer. They are all more or less the same,,, a lacquer based thick bodied filler primer.
The trick to this stuff is not to put on too much at a time,,,, if you put it on too thick it will crack later on. LET IT CURE !! the longer the better! I'm talking WEEKS !!,,, sand it down, spray it again, let it dry,,,, REPEAT,,,, until you get it smooth ! Lacquer shrinks over time! If you do it quickly it will look good now, but later when the stuff shrinks it will look like crap !! Take your time, spray light coats, let it dry, sand, spray some more etc etc, and you won't have to do it again later !!
I'm sure you'll get plenty good advice here on scalemates, Cortex, so don't worry, lot's of good experienced folks here willing to help out!
But any way you look at it, it looks like you've got your work cut out for you !!
GOOD LUCK.

Cortex
I read your entry several times, very informative.
Yeah as you said, I suspected it's not rust because body surface doesn't have this grainy feel when I pass my fingers on it. I'll make an approach list and try the solutions one be one starting from fastest solutions up to tricky ones.
I had the patience test with painting when I did the Monogram Mercedes 300SLR kit, it was my first auto model. And painting it took weeks and the result wasn't even close to desired result, the gloss coat popped all surface and paint defects and I learned few lessons from this build.

Robert W Martel
Also, most bare metals should have what they call a "self etching" or "bare metal" primer as the first coat. Otherwise the primer might chip off easily. Not so sure it's necessary on a model for display, but just to mention it !

Cortex
Thanks : )

Robert W Martel
UR Welcome Cortex,
It's a tricky business painting cars, models or the real ones. It takes time & patience if you want a good finish. I've been back into modeling for the past 3 years or so. I started "practicing" on aircraft kits, and it helped get me decent at spraying. But, most aircraft are flat finished and hide a lot of defects.
When I started doing cars it was a different story !! I've done more than a dozen cars (& more planes too) and am just getting to the point I can put on an "acceptable" finish on car body. Hopefully I'll get better yet. It just takes time & practice !!
I guess it also depends on the kind of paint you are using. Lots of old timers swear by enamels, some use lacquer, I'm forced to use acrylics. I think acrylic is the hardest to get a good finish with. Lacquer is good for fast jobs, but it shrinks over time, defects will show up later! Enamel goes on smooth, stays smooth, but takes a long time to dry. Acrylic is easy to use, but hard to get smooth. It's not all as easy as it would seem !!

Markus Kutsch The Plastic Bench
I just wanted to say again how cool this site is. Robert's example of a detailed explanation of a problem is just an example.Here is help from friend to friend!👍👍👍

Markus Kutsch The Plastic Bench
Any amount of talented model builders here. Almost impossible to comment on all posts. Thanks a hearty "Very well done" to all builders

Robert W Martel
Cortex,
Markus is right, there are many VERY talented & experienced modelers here on Scalemates. But, it is almost impossible to keep track of every post in the News Feed. I just happened across yours because every few days I get an extra few minutes and I click on the News Feed column. Everything that every member post shows up there as they are posted. If I see something interesting I check it out and sometimes make a comment. Then when someone else comments on the same post I get notifications of others that also comment on whatever it was that I looked at. Makes it easy to keep referring back to somebody's build I want to watch.
There's a LOT of stuff here on Scalemates. A great place for reference, ideas & information. I've only been a member for about 6 months and just getting to know my way around. I'm on here every day! If you want to find a review for a particular kit, it's probably here. If you're looking for someone that has built a certain model, it's probably here.
It's a great site for modelers, I'm glad I joined up !