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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Modern car paint and rust



 
 
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  #11  
Old February 16th 17, 12:21 AM posted to rec.crafts.metalworking
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Posts: 231
Default Modern car paint and rust

On Wednesday, February 15, 2017 at 5:19:11 PM UTC-5, amdx wrote:
On 2/12/2017 4:03 PM, wrote:
On Sunday, February 12, 2017 at 3:01:15 PM UTC-5, Clare wrote:
On Sun, 12 Feb 2017 10:43:40 -0800 (PST), Christopher Tidy
wrote:

Hi folks,

Quick question. Many cars from the 1980s used to rust badly. Sometime in the 1990s, this changed - and quite suddenly. Does anyone know what specific changes were made to the paint composition and surface treatment? I can only find vague allusions in most articles.

Thanks,

Chris
Big thing was change to the surface preparation of the steel to
either electrostatic wet application or full body dip of a high
quality etching primer which I believe contains Zinc.
This was combined with the use of high strength steels and
"galvanized" steel in rust prone areas.


Right. It's better coatings, better primers and protection, and better application. Read, water-based coatings that often are based on urethanes; phosphate and weldable, etching primers; galvanizing in rust-prone areas; and electrophoresis and electrostatic application. The first water-based coatings -- used into the '80s by some manufacturers -- had poor adhesion and didn't weather well. They're MUCH better now.

All of this became more necessary as body panels got thinner, with the use of AHSS (advanced high-strength steels; a continuing evolution of the HSLA [high-strength, low-alloy] steels that were first used in the '70s). Rust is potentially a bigger problem than ever because the steel is thinner.


Why the change to base plus clear coat?
I took an auto body class in high school, we had lacquer and enamel,
44 years ago.
The hood on my sons Toyota had faded and was blotchy. So I went to
the paint store to buy paint. I thought I wanted lacquer, I was quickly
educated that I wanted a base and a clear coat. It turned out good
especially for an outdoor job. We did end up with a small hazy area,
when we started the motor to move it in the garage, before the dew came.
Just one area on the right side near the windshield. I suspect
it would buff out, but he took the car back to college, so haven't
tried. Mikek


Clear coats retain their gloss much longer than standard base coats -- up to eight years for some current ones -- and they contain IR blockers that extend the color life of base coats. They've been standard for years.

That is, for the common "three-wet" (primer, base, clear coat) systems used by most OEMs. As I mentioned earlier, Ford, among others, has gone to a "two-wet" system for commercial vehicles and probably will go that way for cars. The current two-wet system used by Ford supposedly maintains gloss for eight years without a clear coat, but it only works in light colors for now..

These are chemically so far removed from our experience with lacquers and enamels that it takes an expert to explain them accurately.

--
Ed Huntress
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  #12  
Old February 16th 17, 01:25 AM posted to rec.crafts.metalworking
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Posts: 128
Default Modern car paint and rust

Am Dienstag, 14. Februar 2017 03:43:47 UTC+1 schrieb :

If you want to talk to someone who specializes in this stuff, I may be able to get you some names.


Thanks, Ed. That's a kind offer. Here's the question in a different form. I'm working on a book and I want to know how to get a coating with a similar performance (modern car paint is, as far as I can see, way better than anything I can get in the shop). It doesn't have be a unique or comprehensive answer, but it needs to be a practical and understandable method. Any idea of someone who could help?

Best wishes,

Chris
  #13  
Old February 16th 17, 01:28 AM posted to rec.crafts.metalworking
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Posts: 128
Default Modern car paint and rust

Am Dienstag, 14. Februar 2017 14:52:42 UTC+1 schrieb Larry Jaques:

Have you talked with painters or automotive paint supply shops there
across the pond, Chris? They're fonts of knowledge, if you can get
them to spare you a few minutes.


Good idea. I don't know of a specialist shop in the area, but I can look for one.
  #14  
Old February 16th 17, 02:32 AM posted to rec.crafts.metalworking
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Posts: 7
Default Modern car paint and rust

On Wed, 15 Feb 2017 15:21:34 -0800 (PST), wrote:

On Wednesday, February 15, 2017 at 5:19:11 PM UTC-5, amdx wrote:
On 2/12/2017 4:03 PM,
wrote:
On Sunday, February 12, 2017 at 3:01:15 PM UTC-5, Clare wrote:
On Sun, 12 Feb 2017 10:43:40 -0800 (PST), Christopher Tidy
wrote:

Hi folks,

Quick question. Many cars from the 1980s used to rust badly. Sometime in the 1990s, this changed - and quite suddenly. Does anyone know what specific changes were made to the paint composition and surface treatment? I can only find vague allusions in most articles.

Thanks,

Chris
Big thing was change to the surface preparation of the steel to
either electrostatic wet application or full body dip of a high
quality etching primer which I believe contains Zinc.
This was combined with the use of high strength steels and
"galvanized" steel in rust prone areas.

Right. It's better coatings, better primers and protection, and better application. Read, water-based coatings that often are based on urethanes; phosphate and weldable, etching primers; galvanizing in rust-prone areas; and electrophoresis and electrostatic application. The first water-based coatings -- used into the '80s by some manufacturers -- had poor adhesion and didn't weather well. They're MUCH better now.

All of this became more necessary as body panels got thinner, with the use of AHSS (advanced high-strength steels; a continuing evolution of the HSLA [high-strength, low-alloy] steels that were first used in the '70s). Rust is potentially a bigger problem than ever because the steel is thinner.


Why the change to base plus clear coat?
I took an auto body class in high school, we had lacquer and enamel,
44 years ago.
The hood on my sons Toyota had faded and was blotchy. So I went to
the paint store to buy paint. I thought I wanted lacquer, I was quickly
educated that I wanted a base and a clear coat. It turned out good
especially for an outdoor job. We did end up with a small hazy area,
when we started the motor to move it in the garage, before the dew came.
Just one area on the right side near the windshield. I suspect
it would buff out, but he took the car back to college, so haven't
tried. Mikek


Clear coats retain their gloss much longer than standard base coats -- up to eight years for some current ones -- and they contain IR blockers that extend the color life of base coats. They've been standard for years.

That is, for the common "three-wet" (primer, base, clear coat) systems used by most OEMs. As I mentioned earlier, Ford, among others, has gone to a "two-wet" system for commercial vehicles and probably will go that way for cars. The current two-wet system used by Ford supposedly maintains gloss for eight years without a clear coat, but it only works in light colors for now.

These are chemically so far removed from our experience with lacquers and enamels that it takes an expert to explain them accurately.

A number of years back, I had my '90 lumina van in to the dealers for
some type of service and the service advisor recomended that I visit
thier body shop about the clear coat failure on the (black) area above
the front seating section. They gave me a "quote" of $750.00 reduced
by 50% to $350.00 to return it to "as new". A few months latter, he
practicaly begged me toget it fixed for free. I presume thet it didn't
look good for GM's reputation.
  #16  
Old February 16th 17, 03:06 PM posted to rec.crafts.metalworking
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Posts: 1,280
Default Modern car paint and rust

On Thu, 16 Feb 2017 07:42:21 -0600
Ignoramus20725 wrote:

Ed, if I buy a modern car like a Honda, how long can I realistically
expect them to last?


You got any repo lots around where they sell stuff? I've got a big one
not too far away and it's very educational to look through. All sorts
of models, years and condition with no cleanup, prepping done for
resale.

I spend most of my time looking underneath the vehicles. The
front wheel well on the Honda CRV is quite interesting. Doesn't look
like a very long lived design for this area and road salt.

Another one that caught my eye was a Buick Rendezvous. The gas filler
is located above the rear wheel well. The filler pipe is in the well
with a thin protective material over some of it.

The Chevy Colorado that has all the emergency brake cable connections
inline with where the left front tire will throw all the road spray on
them.

The 2007 Chevy Silverado that had rear frame rails with major crusty
rust trouble.

Most people look at the body color/paint, interior... I get down and
look all around underneath. The exhaust, drive shaft, suspension,
wheel wells, emergency brake cables, frame rails

--
Leon Fisk
Grand Rapids MI/Zone 5b
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  #17  
Old February 16th 17, 03:48 PM posted to rec.crafts.metalworking
dpb
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Posts: 12,351
Default Modern car paint and rust

On 02/16/2017 8:06 AM, Leon Fisk wrote:
....

Most people look at the body color/paint, interior... I get down and
look all around underneath. The exhaust, drive shaft, suspension,
wheel wells, emergency brake cables, frame rails


Years and years ago (before 1978 as hadn't made the TN from VA move yet)
used to travel to Cleveland and Wickliffe, OH, regularly for employer as
had a major subsidiary/vendor there. Once coming back to catch the
corporate flight back to Lynchburg that evening, an old rust-bucket
pickup literally did hit a serious pothole in the pavement and the frame
buckled behind the cab to the pavement. Created quite a backup pretty
quickly; fortunately I was able to get past and on to make the flight
but was educational!

I remember also that all the freeways were just littered with mufflers
and other body parts that had rusted to the point of falling off...not
what we were used to in Lynchburg, VA, or even in KS where, while it's
cold, it's so much drier don't have the rust issues.

--



  #18  
Old February 16th 17, 04:13 PM posted to rec.crafts.metalworking
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Posts: 569
Default Modern car paint and rust

On 2/16/2017 7:42 AM, Ignoramus20725 wrote:
On 2017-02-12, wrote:

Right. It's better coatings, better primers and protection, and
better application. Read, water-based coatings that often are based
on urethanes; phosphate and weldable, etching primers; galvanizing
in rust-prone areas; and electrophoresis and electrostatic
application. The first water-based coatings -- used into the '80s by
some manufacturers -- had poor adhesion and didn't weather
well. They're MUCH better now.

All of this became more necessary as body panels got thinner, with
the use of AHSS (advanced high-strength steels; a continuing
evolution of the HSLA [high-strength, low-alloy] steels that were
first used in the '70s). Rust is potentially a bigger problem than
ever because the steel is thinner.


Ed, if I buy a modern car like a Honda, how long can I realistically
expect them to last?


A bit of an open ended question.
I have a 97 Toyota T-100 that still looks beautiful and runs great.
Will admit we had the sides of the bed repainted, not because of any
problem but because we used as a work truck and the idiots that loaded
it rubbed their belt buckles on the bed as they loaded it. They put a
bunch of scratches in the paint. I'm in the Florida sun and after 20
years the roof and hood still look good, we do garage it though.
Mikek

---
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  #20  
Old February 16th 17, 05:55 PM posted to rec.crafts.metalworking
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Posts: 1,280
Default Modern car paint and rust

On Thu, 16 Feb 2017 09:13:56 -0600
amdx wrote:

snip
I have a 97 Toyota T-100 that still looks beautiful and runs great.
Will admit we had the sides of the bed repainted, not because of any
problem but because we used as a work truck and the idiots that loaded
it rubbed their belt buckles on the bed as they loaded it. They put a
bunch of scratches in the paint. I'm in the Florida sun and after 20
years the roof and hood still look good, we do garage it though.


They have a reputation in the rustbelt

https://duckduckgo.com/html/?q=toyot...t+recall&kd=-1

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

 




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