Surface rust and oxidation clean up

[bennyblanco99]

Hey everyone - I've been cleaning up the underside of my card for many months now and I have yet to figure out what the best and/or easiest way to clean surface rust on components on or off the car.  For example, I'm trying to clean up this minor oxidation on the muffler heat shield and for the life of me I can't get it cleaned up. 

 

What are the suggestions from those with experience?  I appreciate any advice!

[Pfeil]

Have you sand blasted it with sand/silica, then used metal prep (acid) with steel wool? Remember after use, you have to immediately use a neutralizer dry it and prime it. The black oxide spots must be removed.

Edited April 1 by Pfeil (see edit history)

[ABear]

Chances are the metal under the raised rusted spots is pitted, never going to look show room quality again because it is a heat shield.

 

You can stop the rust, use some sand paper to knock off the high spots, make sure no loose rust is present, then treat the surface with OSPHO which is a rust converter. The Ospho converts the rust to a black paintable surface, won't rust any more.

 

You can coat the entire shield with Ospho which on non rusted spots it will etch into the metal which will give your high temp paint a good grip to the metal.

 

https://www.ospho.com/

 

Once the Opsho has done it's job, you can top coat with paint. In your case, you will need a high temperature paint like BBQ grill black paint or, you can try weld through primer..

 

Weld through primer is typically used when welding metal together that can't be easily accessed later to seal and paint. Not cheap but is very effective and should withstand the heat generated by the exhaust system without burning off.

 

I would recommend U-Pol Copper Rich weld through primer, it will give the shield a copper like look.

 

https://www.amazon.com/U-POL-Weld-Through-Copper-Primer/dp/B0026KCJ1K

 

You do not need to top coat over top of the U-Pol primer.

 

They also make a copper/zinc version but I believe that is grey/green in color.

[GloriaNdongo]

Hey there! Dealing with surface rust can indeed be a hassle, but don't worry, you're not alone in this struggle! When it comes to cleaning up minor oxidation like on your muffler heat shield, there are a few tried and true methods that might help:

1. Wire Brush or Steel Wool: Using a wire brush or steel wool can be effective in removing surface rust. Just be gentle to avoid scratching the surface.

2. Sandpaper: If the rust is stubborn, sandpaper might be your best bet. Start with a coarse grit to remove the bulk of the rust, then switch to a finer grit for smoothing and polishing.

3. Chemical Rust Removers: There are many rust removal products available on the market. Make sure to follow the instructions carefully and wear protective gear when using these chemicals.

4. Vinegar or Lemon Juice: For a more natural approach, you can try soaking the rusted area in vinegar or lemon juice. The acidity helps to dissolve the rust.

5. Rust Converter: Rust converters chemically convert iron oxide (rust) into a more stable compound, stopping further rusting. This can be a good option for preventing future rust.

6. Protective Coating: Once you've removed the rust, consider applying a protective coating like paint or a rust inhibitor to prevent it from coming back.

https://gloriacleaning.com/deep-cleaning-bronx-ny/

Remember, patience is key when dealing with rust removal. It might take some trial and error to find the method that works best for your specific situation. Hang in there, and let us know how it goes!

[TAKerry]

Bots are getting smarter, Im afraid to click on the link for the business?

[28 Chrysler]

On a heat shield there is a reflective coating, most likely an acid might remove it. Who is going to look at a heat shield?

[Mark Shaw]

On 4/1/2024 at 12:29 PM, ABear said:

You can coat the entire shield with Ospho which on non rusted spots it will etch into the metal which will give your high temp paint a good grip to the metal.

 

https://www.ospho.com/

Best option IMO.

[ABear]

1 hour ago, 28 Chrysler said:

On a heat shield there is a reflective coating, most likely an acid might remove it. Who is going to look at a heat shield?

Etching with OSPHO, will not "remove" any coatings, it etches into existing coatings chemically to provide a substantially improved surface for paint or other coatings to bond to. Case in point is when you encounter galvanized treated metal, the galvanized layer protects the metal under it but in doing so, getting paint to stick to galvanized layer is impossible to do without using specialized etching primers which do the exact same thing as OPSHO.

 

The big difference between etching primer and OSPHO is most etching primers tend to not be as effective on multiple types of metals and surfaces.

 

I have used OSPHO to not only act as a rust converter, but as an etching agent on galvanized surfaces, aluminum surfaces and stainless steel surfaces in order to prep those for paint. So far, have had zero issues getting paint to stick to meatls that typically do not accept paint well.

 

As far as heat shields having a reflective surface, never seen that, pretty much every heat shield I have seen has a heat resistant coating, not a paint, but a surface coating.. I doubt that coating is to reflect heat but more there to reduce rusting out of the shield. Sort of like "aluminized" coating on exhaust parts was used to extend the life of exhaust systems until stainless steel started being commonly used  on modern vehicles.

 

Combine the OSPHO to treat surface rust and etch what isn't rusted and then top coating with BBQ black or my favorite of copper rich weld through primer and the shield should outlast the rest of the untreated exhaust system. The copper coat will add some reflective quality if that is your primary concern, BBQ black may absorb a bit more heat but in reality the shield is simply there to block some exhaust heat from getting into the floor pans..

[James Matthews]

bennyblanco99, thank you for posting this question. There seems to be a lot of good information in this post which I think I can use!

[ABear]

When you live in the rust belt, one must learn how to manage the rust.

 

Rust never sleeps..

 

Should point out, OSPHO should be top coated, not recommended for outdoor use without a coat of paint over top.

[3macboys]

Anyone notice the date of the original post?

[TAKerry]

8 hours ago, 3macboys said:

Anyone notice the date of the original post?

And yet another one and done! 

[Rusty_OToole]

If I ever get that anal I would give it a rub with steel wool and paint it with high temp aluminum paint. Give it 2 coats and it will last forever.

[bennyblanco99]

On 4/9/2024 at 7:05 AM, TAKerry said:

And yet another one and done! 

Im still around, sorry all.  I appreciate the input - deal with my Dad in the hospital the past few days.    

 

I'm trying to get my car back to near mint condition and I'm going through the underbody piece by piece.  The muffler is my latest project and figured there had to be a better way.  I'm going to look at some of these ideas and work on it shortly.  Will post results when I get it done, promise!

 

[36 D2 Coupe]

Here's something I just discovered today for cleaning oxidized aluminum trim - specifically the doorsill trim on our '36 Dodge coupe. I carefully removed them from the car - discovered I needed a heat gun as in 1936 they were bedded in dumdum to seal them to the body. I had bought replacement doorsills but decided to see if I could clean these up. Looking online for ideas I discovered I have the cure hidden under our kitchen sink! It's a product called Barkeepers Friend that my wife uses to keep everything bright and shiny. With some of this and a bit of elbow grease the initial results are encouraging. It removes heavy oxidation without damaging anything and leaves the old parts quite presentable with a lot less work than other polishes and cleaners. We love it for sinks and stoves and things but this is an unexpected bonus.

My wife says I have to give it back😄

Edited April 11 by 36 D2 Coupe (see edit history)

[ABear]

Bar keepers friend does wonders for cleaning stainless and copper, might work with brass and aluminum..

 

We use it for our kitchen pots and pans which are stainless with copper bottoms.

 

However, do be careful with it's use, it is abrasive so tread carefully on irreplaceable parts.

Edited April 11 by ABear (see edit history)

[TAKerry]

10 hours ago, bennyblanco99 said:

Im still around, sorry all.  I appreciate the input - deal with my Dad in the hospital the past few days.    

 

I'm trying to get my car back to near mint condition and I'm going through the underbody piece by piece.  The muffler is my latest project and figured there had to be a better way.  I'm going to look at some of these ideas and work on it shortly.  Will post results when I get it done, promise!

 

I humbly apologize for my rudeness. So many one and doners, not to mention the bots getting smarter. Now that I know youre a real human, I will give my 2c for what its worth. Evaporust does wonders. I have a small Milwaukee cordless angle die grinder. I use a rolocs on it from coarse to fine depending on corrosion. This thing is my new go to. It works miracles cleaning oxidized metal. 

20240406_172628 by Kerry Grubb, on Flickr

Before20240409_083058 by Kerry Grubb, on Flickr

After an evaporust soak. This is just with a wash down no real clean up. Once I hit it with my roloc it looked almost new again.

20240403_183420 by Kerry Grubb, on Flickr

20240403_185352 by Kerry Grubb, on Flickr

The exhaust is not really a good example as they are stainless but had a coating of who knows what on them. In the first pic you can barely see my little miracle maker. 

IF it looks too bad after clean up then yes, I would hit with some high temp silver paint. 

 

[bennyblanco99]

13 hours ago, 36 D2 Coupe said:

Here's something I just discovered today for cleaning oxidized aluminum trim - specifically the doorsill trim on our '36 Dodge coupe. I carefully removed them from the car - discovered I needed a heat gun as in 1936 they were bedded in dumdum to seal them to the body. I had bought replacement doorsills but decided to see if I could clean these up. Looking online for ideas I discovered I have the cure hidden under our kitchen sink! It's a product called Barkeepers Friend that my wife uses to keep everything bright and shiny. With some of this and a bit of elbow grease the initial results are encouraging. It removes heavy oxidation without damaging anything and leaves the old parts quite presentable with a lot less work than other polishes and cleaners. We love it for sinks and stoves and things but this is an unexpected bonus.

My wife says I have to give it back😄

What did you use to apply/work it to the trim?

[bennyblanco99]

4 hours ago, TAKerry said:

I humbly apologize for my rudeness. So many one and doners, not to mention the bots getting smarter. Now that I know youre a real human, I will give my 2c for what its worth. Evaporust does wonders. I have a small Milwaukee cordless angle die grinder. I use a rolocs on it from coarse to fine depending on corrosion. This thing is my new go to. It works miracles cleaning oxidized metal. 

20240406_172628 by Kerry Grubb, on Flickr

Before20240409_083058 by Kerry Grubb, on Flickr

After an evaporust soak. This is just with a wash down no real clean up. Once I hit it with my roloc it looked almost new again.

20240403_183420 by Kerry Grubb, on Flickr

20240403_185352 by Kerry Grubb, on Flickr

The exhaust is not really a good example as they are stainless but had a coating of who knows what on them. In the first pic you can barely see my little miracle maker. 

IF it looks too bad after clean up then yes, I would hit with some high temp silver paint. 

 

I have Evaporust in my arsenal, but it is hard to apply when working the underbody.  I've tried soaking a rag and leaving it on and it's worked decently.  I believe I also have a gel form and it works well too.  I guess there are many ways to accomplish the things I want to do, but all involve elbow grease

 

How did you soak that large pipe in the Evaporust?    I thinkt he rolocs works fine on something like stainless, but is a bit too rough on this aluminum piece.

[36 D2 Coupe]

The product  I use is their wettable powder.  Comes in a can with holes in the top to shake it out. Use a wet rag and sprinkle some Barkeepers Friend on it. Rub vigorously, then rinse with clear water. 

I would disagree with ABear -it doesn't appear to pose any risk to the fine detailed etching on the aluminum sill plates. I believe the active ingredient is oxalic acid which is a great corrosion remover on a number of metals. 

But it may not address the pitting I see in your photo.

Hope this helps.

Edited April 11 by 36 D2 Coupe (see edit history)

[ABear]

22 minutes ago, 36 D2 Coupe said:

The product  I use is their wettable powder.  Comes in a can with holes in the top to shake it out. Use a wet rag and sprinkle some Barkeepers Friend on it. Rub vigorously, then rinse with clear water. 

I would disagree with ABear -it doesn't appear to pose any risk to the fine detailed etching on the aluminum sill plates. I believe the active ingredient is oxalic acid which is a great corrosion remover on a number of metals. 

But it may not address the pitting I see in your photo.

Hope this helps.

Yes, main active ingredient of Barkeepers is oxalic acid, however it DOES have a fine grit feel to it even when wet. That can be confirmed by placing some BK with moisture between two metal objects and move them together. You will hear and feel the grit grinding.

 

For our stainless pans with copper bottoms if I use BK on the bottom and do not wash it off fully I can sit the pan in the sink and hear and feel the grit if I drag the pan.

 

Our pans are not highly polished so I really do not know how much or how little of impact there may be by using it on trim. I do know that the copper cleans nice, but it does not have any polished gloss look when done.

 

As far as removing fine details, most likely not to much but in soft metals like aluminum, copper, brass the possibility is you may introduce micro scratches, if the aluminum, copper, brass surface was originally polished, it may result in a less polished finish if not careful.

 

You will not notice the grit feel using sponge or cloth with it, but it is present.

 

 

[bennyblanco99]

2 hours ago, ABear said:

Yes, main active ingredient of Barkeepers is oxalic acid, however it DOES have a fine grit feel to it even when wet. That can be confirmed by placing some BK with moisture between two metal objects and move them together. You will hear and feel the grit grinding.

 

For our stainless pans with copper bottoms if I use BK on the bottom and do not wash it off fully I can sit the pan in the sink and hear and feel the grit if I drag the pan.

 

Our pans are not highly polished so I really do not know how much or how little of impact there may be by using it on trim. I do know that the copper cleans nice, but it does not have any polished gloss look when done.

 

As far as removing fine details, most likely not to much but in soft metals like aluminum, copper, brass the possibility is you may introduce micro scratches, if the aluminum, copper, brass surface was originally polished, it may result in a less polished finish if not careful.

 

You will not notice the grit feel using sponge or cloth with it, but it is present.

 

 

BK definitely has some sort of grit material in it.  I have the powder and the liquid form and both are similarly textured.  That said, it would have to be a very soft metal to introduce any noticeable scratching, I think. 

[Bloo]

I'm not knocking barkeepers friend, and I always keep some around. There are other ways to buy oxalic acid though if one so desires. The crystals are on amazon (mix it yourself, no grit!) or maybe at the local pharmacy if you are lucky. I use it on small hardware sometimes.

 

Based on what I have seen on TheCabe (bicycle forum) I believe oxalic acid may lift less paint from painted parts than evaporust or electrolytic derusting which is a third option. Paint comes off anyway if there is rust underneath, and there probably is. Any of the three are likely to remove plating in my opinion.

 

[EmTee]

1 hour ago, Bloo said:

There are other ways to buy oxalic acid though if one so desires.

I have a small tub of Wood Bleach on the shelf in my garage.

 

[36 D2 Coupe]

5 hours ago, ABear said:

Yes, main active ingredient of Barkeepers is oxalic acid, however it DOES have a fine grit feel to it even when wet. That can be confirmed by placing some BK with moisture between two metal objects and move them together. You will hear and feel the grit grinding.

 

For our stainless pans with copper bottoms if I use BK on the bottom and do not wash it off fully I can sit the pan in the sink and hear and feel the grit if I drag the pan.

 

Our pans are not highly polished so I really do not know how much or how little of impact there may be by using it on trim. I do know that the copper cleans nice, but it does not have any polished gloss look when done.

 

As far as removing fine details, most likely not to much but in soft metals like aluminum, copper, brass the possibility is you may introduce micro scratches, if the aluminum, copper, brass surface was originally polished, it may result in a less polished finish if not careful.

 

You will not notice the grit feel using sponge or cloth with it, but it is present.

 

 

I do agree it does have a grittiness to it but for the cleaning of something heavily oxidized, like the doorsill plates,  micro scratches are likely already there. And it does make them presentable although certainly not Concours quality. For a highly polished surface, it may not be the best choice.