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Can I save the paint while dealing with this rust?
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67rustavenger Premium Member
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PostPosted: Sat Jul 16, 2016 1:55 pm    Post subject: Can I save the paint while dealing with this rust? Reply with quote

I searched and cannot find the solution to my unique issue. I have some light rust in the engine bay that I would like to neutralize without destroying my OG paint. I have scrubbed it some and made the rust go away a little. But not completely. Is there a way to deal with this issue without having to repaint the area? I have chosen this location to experiment as it will be out of sight.

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There are a few other areas that need attention with the same issue. Like the engine bay intake vent below the rear window.
Thanks in advance for any suggestions that assist with this problem.
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panicman
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PostPosted: Tue Jul 19, 2016 8:13 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

You've gone a couple days now with no response, so here is what I might try, going from least potentially damaging to most:

Lemon juice and a soft toothbrush

Rubbing compound, microfiber cloth

Wet sand with 1500 grit

I imagine the paint is weakened in those areas, and may fail completely if you scrub, rub, or sand.

If these fail, and you are not committed to a partial or total paint job, this is one place you could probably get away with a close Krylon or Rustoleum match. I would scuff the engine bay with a red scotchbrite pad, use Napa rust converter on any visible surface rust, and then carefully cover it with your closely matched canned paint. If you park outside, I would consider this a temporary repair. I wouldn't try this on the cars exterior, either, but do read through the Krylon threads and PM some of the users who have managed to use rattle can and have it last.

Hopefully someone swoops in with a more clever trick.
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Joseph DR
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PostPosted: Tue Jul 19, 2016 6:00 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

I'm wondering if he could just spritz it with phosphoric acid and be done?
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PostPosted: Tue Jul 19, 2016 10:35 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

That was one of my first ideas, but I think it will turn the rust black, which will really show against the white paint.
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PostPosted: Wed Jul 20, 2016 8:49 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

Joseph DR wrote:
I'm wondering if he could just spritz it with phosphoric acid and be done?


Thjs is the right thing to do...partially.

You can:
A. Use a strong phosphoric acid solution like Jasco metal prep and prime.....undiluted. ...which will dissolve ALL of the rust to bare metal. This will also show you where the rust has moved laterally under the paint.
Rinse....quickly dry...and repaint with something that matches.

B. You can do what I listed under A .....but then let it flash rust slightly and spritz it with diluted phosphoric acid (either ospho or jasco mixed about 60/40 with water)......wipe the excess off the surrounding paint, leave it wet until it dries completely. ....which wi turn it black where the flash rust was.

This is PERFECT primer. ....then paint it.

C. Or you can just spritz it with ospho as originally noted.....which is diluted phosphoric acid.....let it turn completely black and then paint it.

Personally I like to remove rust completely. In this way you know it will not come back.

The issue is that if the rust us even a couple of thousandths too thick for using diluted phosphoric acid.....it just encapsulates the rust and it keeps growing.

Ray
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PostPosted: Wed Jul 20, 2016 10:52 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

raygreenwood wrote:
.....it just encapsulates the rust and it keeps growing.

Ray


Ray, is that really the case? I was under the impression that if the rust is encapsulated, no oxygen can get to it, so the main catalyst for the iron oxide reaction is no longer present?
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PostPosted: Wed Jul 20, 2016 1:31 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

beetlenut wrote:
raygreenwood wrote:
.....it just encapsulates the rust and it keeps growing.

Ray


Ray, is that really the case? I was under the impression that if the rust is encapsulated, no oxygen can get to it, so the main catalyst for the iron oxide reaction is no longer present?


Iron oxide.....contains oxygen. Encapsulating it just slows it down.. ..but does not stop it from rusting.

This is what far too many do not understand about rust and rust converters.

For example.....if you use a basic diluted rust converter on rust that is too thick....generally more than about .003" thick......it can only convert about 1/3 to 1/2 that depth because as the phosphoric acid is converting rust to iron phosphate.....it is being neutralized. And once you have a converted top layer.....additional phosphoric acid cannot reafily penetrate it.

So you convert thick rust.....and a few months later it starts specking and pentrating with rust blooms from below.

So.....either remove the rust entirely.....safer way with strong phosphoric acid. ...or if its deep crusty rust....use muriatic acid and then neutralize.

Then you need to let it flash rust for a couple of days. Flash rust is less than .002" thick. There has to be some iron oxide (rust) for phosphoric acid to convert to iron phosphate to make primer. Ray
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PostPosted: Wed Jul 20, 2016 5:52 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

raygreenwood wrote:
beetlenut wrote:
raygreenwood wrote:
.....it just encapsulates the rust and it keeps growing.

Ray


Ray, is that really the case? I was under the impression that if the rust is encapsulated, no oxygen can get to it, so the main catalyst for the iron oxide reaction is no longer present?


Iron oxide.....contains oxygen. Encapsulating it just slows it down.. ..but does not stop it from rusting.

This is what far too many do not understand about rust and rust converters.

For example.....if you use a basic diluted rust converter on rust that is too thick....generally more than about .003" thick......it can only convert about 1/3 to 1/2 that depth because as the phosphoric acid is converting rust to iron phosphate.....it is being neutralized. And once you have a converted top layer.....additional phosphoric acid cannot reafily penetrate it.

So you convert thick rust.....and a few months later it starts specking and pentrating with rust blooms from below.

So.....either remove the rust entirely.....safer way with strong phosphoric acid. ...or if its deep crusty rust....use muriatic acid and then neutralize.

Then you need to let it flash rust for a couple of days. Flash rust is less than .002" thick. There has to be some iron oxide (rust) for phosphoric acid to convert to iron phosphate to make primer. Ray


OK, I understand everything after the first sentence. But I thought that once the oxygen contained in the iron oxide is depleted, once sealed, the reaction cannot continue. Or is it that there is too much remaining oxygen in the iron oxide, so even once sealed, the reaction continues?
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... I spend more time shaking it than directing it?! I get a pretty decent blast for 8sec. then have to shake it again.
- Words to live by right there!

My 74 Super rebuild thread: http://www.thesamba.com/vw/forum/viewtopic.php?p=6507104#6507104
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PostPosted: Wed Jul 20, 2016 11:54 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

beetlenut wrote:
raygreenwood wrote:
beetlenut wrote:
raygreenwood wrote:
.....it just encapsulates the rust and it keeps growing.

Ray


Ray, is that really the case? I was under the impression that if the rust is encapsulated, no oxygen can get to it, so the main catalyst for the iron oxide reaction is no longer present?


Iron oxide.....contains oxygen. Encapsulating it just slows it down.. ..but does not stop it from rusting.

This is what far too many do not understand about rust and rust converters.

For example.....if you use a basic diluted rust converter on rust that is too thick....generally more than about .003" thick......it can only convert about 1/3 to 1/2 that depth because as the phosphoric acid is converting rust to iron phosphate.....it is being neutralized. And once you have a converted top layer.....additional phosphoric acid cannot reafily penetrate it.

So you convert thick rust.....and a few months later it starts specking and pentrating with rust blooms from below.

So.....either remove the rust entirely.....safer way with strong phosphoric acid. ...or if its deep crusty rust....use muriatic acid and then neutralize.

Then you need to let it flash rust for a couple of days. Flash rust is less than .002" thick. There has to be some iron oxide (rust) for phosphoric acid to convert to iron phosphate to make primer. Ray


OK, I understand everything after the first sentence. But I thought that once the oxygen contained in the iron oxide is depleted, once sealed, the reaction cannot continue. Or is it that there is too much remaining oxygen in the iron oxide, so even once sealed, the reaction continues?


Have you ever looked at rust under a microscope?......its HUGELY porous. It contains at a minimum.....moisture....water......which contains oxygen.

Rust encapsulation.....is BS.....it only delays it.
Ray
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PostPosted: Thu Jul 21, 2016 6:26 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

raygreenwood wrote:
beetlenut wrote:
raygreenwood wrote:
beetlenut wrote:
raygreenwood wrote:
.....it just encapsulates the rust and it keeps growing.

Ray


Ray, is that really the case? I was under the impression that if the rust is encapsulated, no oxygen can get to it, so the main catalyst for the iron oxide reaction is no longer present?


Iron oxide.....contains oxygen. Encapsulating it just slows it down.. ..but does not stop it from rusting.

This is what far too many do not understand about rust and rust converters.

For example.....if you use a basic diluted rust converter on rust that is too thick....generally more than about .003" thick......it can only convert about 1/3 to 1/2 that depth because as the phosphoric acid is converting rust to iron phosphate.....it is being neutralized. And once you have a converted top layer.....additional phosphoric acid cannot reafily penetrate it.

So you convert thick rust.....and a few months later it starts specking and pentrating with rust blooms from below.

So.....either remove the rust entirely.....safer way with strong phosphoric acid. ...or if its deep crusty rust....use muriatic acid and then neutralize.

Then you need to let it flash rust for a couple of days. Flash rust is less than .002" thick. There has to be some iron oxide (rust) for phosphoric acid to convert to iron phosphate to make primer. Ray


OK, I understand everything after the first sentence. But I thought that once the oxygen contained in the iron oxide is depleted, once sealed, the reaction cannot continue. Or is it that there is too much remaining oxygen in the iron oxide, so even once sealed, the reaction continues?


Have you ever looked at rust under a microscope?......its HUGELY porous. It contains at a minimum.....moisture....water......which contains oxygen.

Rust encapsulation.....is BS.....it only delays it.
Ray


Can't say I have ever looked at rust under a microscope, although my ophthalmologist has as he picked it out of my eye on more than one occasion! So thanks Ray, good to know the real story since most of us only know what the companies that push the rust encapsulation products have to tell us.
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Wetstuff wrote:
... I spend more time shaking it than directing it?! I get a pretty decent blast for 8sec. then have to shake it again.
- Words to live by right there!

My 74 Super rebuild thread: http://www.thesamba.com/vw/forum/viewtopic.php?p=6507104#6507104
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PostPosted: Thu Jul 21, 2016 1:03 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

This is not saying that all forms of rust encapsulation and rust encapsulation products are bad.

Some work very well....and like POR-15...which uses a phosphoric acid solution as a primer to convert as much of the rust...IT CAN REACH...to iron phosphate which is a great primer for their product.

There are times and places where you do not have the safe option to either mechanically grind or blast all rust away to clean metal....

.....or you cannot use phosphoric or muriatic acid to dissolve rust because you cannot get to all adjacent areas that the acid may flow into to neutralize the acid (like inside of heater channels or frame cavities.....or for instance you may be working on getting rust out of areas behind the dash and you still have wiring close by.
The vapors from acid products can attack plated electrical terminals and electronics parts.

Rust encapsulators....good ones....are useful in areas where you cannot reach....but where you have to do something. Mainly they are great for preservation.

Inside of inaccessible frame channels...where rust is light...not huge, thick crusty rust...but general age related surface rust inside of areas that were never factory primed....a rust encapsulator works great.

It may have enough phosphoric acid or other converting ingredient to be self priming...and then form a tough waterproof film.

In slightly thicker rust patches....sooner or later these will start blooming through....but that may be 10 years....and since they have been slowed down and do not have open access to weather and water....you may not have serious rust issues for 20 years.

But...for anything external.....you need too either remove all rust...or convert the rust down too metal...before you paint or encapsulate it. because once its starts blooming through the surface again because it had trapped oxygen in it.....it opens the surface of your paint and coating to let in even more water and oxygen. Ray
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PostPosted: Thu Jul 21, 2016 5:09 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

Hey, Thanks to all who have posted your ideas.
I think first I'll try the lemon and toothbrush idea. That seems gentle enough.
The area in the image is a test spot. I have other locations that have the same surface type of rust (not as bad) but are on the outside of the car and if I make a huge mistake will be very noticeable. The rear engine bay intake vent is one of those areas that I can see being difficult to get to. So the lemon technique is appealing as I can get a toothbrush in there and give it a gentle scrub.
FWIW the car color is Zenithblau.
Have a great weekend.
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PostPosted: Fri Jul 29, 2016 7:40 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

A forum member (skim) uses clr to remove the stains before clear coating. Maybe this could be helpful with your issue


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PostPosted: Fri Jul 29, 2016 7:42 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

Here's a link to other pics of the car when he wa doing it.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/216032/post/1712505/
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PostPosted: Sat Jul 30, 2016 9:48 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

jules9 wrote:
Here's a link to other pics of the car when he wa doing it.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/216032/post/1712505/

Thanks for the link. I can't believe how nice that 59 elco turned out after using CLR on it. Just amazing. I had thought of trying CLR but now well. I'm gonna give it t shot.
Enjoy the ride.
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PostPosted: Sat Jul 30, 2016 11:15 am    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

67rustavenger wrote:
jules9 wrote:
Here's a link to other pics of the car when he wa doing it.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/216032/post/1712505/

Thanks for the link. I can't believe how nice that 59 elco turned out after using CLR on it. Just amazing. I had thought of trying CLR but now well. I'm gonna give it t shot.
Enjoy the ride.


Bear in mind....CLR works...but is slow and has "0" rust conversion protection.....and...it must be rinsed especially well and neutralized before you coat it the bare metal with anything.

It is a descaling, acid based agent using lactic acid and gluconic acid. The third ingredient lauramine oxide is basically a wetting/flow agent of sorts that lets it penetrate scale and rust better.

http://www.jelmar.com/msds/2012/CLR_Calcium_Lime_Rust_MSDS.pdf

Ray
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PostPosted: Sat Jul 30, 2016 12:27 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

[quote="raygreenwood"][quote="67rustavenger"]
jules9 wrote:
Here's a link to other pics of the car when he wa doing it.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/216032/post/1712505/

Bear in mind....CLR works...but is slow and has "0" rust conversion protection.....and...it must be rinsed especially well and neutralized before you coat it the bare metal with anything.

It is a descaling, acid based agent using lactic acid and gluconic acid. The third ingredient lauramine oxide is basically a wetting/flow agent of sorts that lets it penetrate scale and rust better.

Ray


Maybe he can use the clr to get the rust stains off and then use rust converter?
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PostPosted: Sat Jul 30, 2016 1:51 pm    Post subject: Re: Can I save the paint while dealing with this rust? Reply with quote

[quote="jules9"][quote="raygreenwood"]
67rustavenger wrote:
jules9 wrote:
Here's a link to other pics of the car when he wa doing it.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/216032/post/1712505/

Bear in mind....CLR works...but is slow and has "0" rust conversion protection.....and...it must be rinsed especially well and neutralized before you coat it the bare metal with anything.

It is a descaling, acid based agent using lactic acid and gluconic acid. The third ingredient lauramine oxide is basically a wetting/flow agent of sorts that lets it penetrate scale and rust better.

Ray


Maybe he can use the clr to get the rust stains off and then use rust converter?


Rust converter does not work without rust to convert.

Simply easier to use a rust converter to kill and convert what is there.

Here is what everyone is not getting......you keep trying to preserve the paint....like the rust stain is just some kind of external stuff that got on the paint and changed the color.....and you are just looking for some kind of stain remover.

Rust is rust. If there is rust ON the paint stainong it.......then there is rust UNDER the paint immediately adjacent to where you see rust stains on top of the paint.

That means your paint is shot right there. Do yourself and the car a great services....and use either a rust remover or full strength rust converter to DISSOLVE the rust down to clean metal. Then clean away the flaky paint that will be there because the metal surface it was attached to (which was rusted).....bas been dissolved out from underneath it.

Then you can take care of the metal in one of several ways......let it flash rust and convert it and then paint it,with touch up paint (best).....or cokpletely dissolve rust and prime and ghen paint. Ray
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