New Rust Converter Research Results

[doitmyself]

Prompted by Blazes request for treating rusty cars, I wanted to share these recent research results regarding RUST CONVERTERS.

I have had mixed results with rust converters over 20 years, and often they are not the silver bullet that their marketing claim. There have been a few research papers years ago, but this new one seems to support my experience: many have marginal results. I had always favored the more watery phosphoric acid based types, thinking that they wetted and penetrated better. The best one below is the milky latex type.

Enjoy.

http://ncptt.nps.gov/blog/comparative-study-of-commercially-available-rust-converters/

The actual research report:
http://ncptt.nps.gov/wp-content/uploads/metal-paper-88.pdf?1ef327

"Conclusion
After each of the tests were performed and the 1032 hours of accelerated weathering completed, many questions were answered and many were raised. Overall, the Rustoleum®
Rust Reformer® performed the best, with no active corrosion evident and a nice even surface finish intact. The main active ingredient in the Rust Reformer® is tannic acid.
However, the additive acrylic vinylidene chloride copolymer may have been just as important in sealing the metal’s surface. The combination of the two outlasted all other
converters in this study."

 

[Texan4Life]

interesting thx for sharing!

good to know rustoleum is still making top notch products

 

[Blaze]

Thanks!

 

[thescreensavers]

Thanks!

Shame they didn't use more OTC products.

Next time!

 

[Ducked]

Quote from the linked conservators "recipe" paper

"A tannic acid coating will not protect against corrosion in an outdoor environment and will quickly degrade (Binnie et al. 1995)."

This might imply the tannic acid's role is largely or partly cosmetic, and the important part of the rustoleum treatment is the vinyl copolymer.

In other words, they painted it.

I wonder how this, (or other) rust converters would compare in performance with simply using a protective coating such as Fluid Film

 

[JiL]

Originally Posted By: Ducked
In other words, they painted it.


Agree. Fundamentally flawed study: "We tested how well rust converters function as protective coatings."

Treatments that effectively removed rust (as intended) ranked poorly because they didn't prevent its return.

 

[spasm3]

My avalanche has some underbody rust, whoever owned it before me took it on the beach. Am i better off leaving it alone, or trying something like rust doctor underneath? Would the rust converter need to be coated with paint?

 

[Ducked]

Originally Posted By: spasm3
My avalanche has some underbody rust, whoever owned it before me took it on the beach. Am i better off leaving it alone, or trying something like rust doctor underneath? Would the rust converter need to be coated with paint?


I'd say pressure hose it to get salt off first. If you can be bothered to take the carpets and seats out then you can hose it (and subsequently apply protective treatment) from the inside as well, but be careful around electrics.

As hinted above, rust converters are likely to be inadequate alone. Paint is a pain to apply, so something oilier that will creep/soak into crevices and box-sections is favorite. I use a mix of engine oil, diesel fuel and sunflower oil, but there are commercial products (eg Fluid Film) that may be superior.

 

[Donald]

It was an interesting report. But for many of us using the rust converter would only be the first step. Next would be some primer and paint. So many people would only be concerned with how well the rust converter preps the metal for a primer.

But I can see some uses for a rust converter without any paint on top of the treatment.

 

[mdocod]

Hey that's pretty cool. I've been using the Rustoleum Reformer stuff under my isuzu lately to stop rust. Seems to work really nicely to provide a semi-durable prepped surface. I guess that was a good pick after-all! I need to finish what I started though and hit the frame and other metal under there with good durable paint.

 

[doitmyself]

Originally Posted By: Donald
It was an interesting report. But for many of us using the rust converter would only be the first step. Next would be some primer and paint. So many people would only be concerned with how well the rust converter preps the metal for a primer.

But I can see some uses for a rust converter without any paint on top of the treatment.

Donald, JIL, and Ducked,

I came to your same conclusions after initially posting this. Not a flawed study for the investigators because I believe that they are involved with protecting historical items and specifically things like wrought iron fences that they don't want to put paint on.

However, I have used the watery phosphoric acid type treatments on rusty metal, followed by primer and topcoat, only to have rust come through again. My next trial will be the Rustoleum or Corroseal/Rust Doctor type. Maybe the combination of rust converter and acrylic "primer" work well together? I am skeptical of rust covering silver bullets, but it's fun to try. One advantage of these dual rust converter/primers is that they can be used on surfaces that are part rust/bare metal/painted. The watery acid types state to only use on rusted surfaces and/or wipe it off non rusted areas.

Off topic, some 15 years ago I painted a 100% rusted metal T fence post with fish oil based Rustoleum rusty metal primer, followed with a rustoleum top coat. It's been outdoors ever since and is still about 90% rust free. http://www.hantover.com/specsheet_pdf/88387_Spec2.pdf

 

[Donald]

Originally Posted By: doitmyself
Originally Posted By: Donald
It was an interesting report. But for many of us using the rust converter would only be the first step. Next would be some primer and paint. So many people would only be concerned with how well the rust converter preps the metal for a primer.

But I can see some uses for a rust converter without any paint on top of the treatment.

Donald, JIL, and Ducked,

I came to your same conclusions after initially posting this. Not a flawed study for the investigators because I believe that they are involved with protecting historical items and specifically things like wrought iron fences that they don't want to put paint on.

However, I have used the watery phosphoric acid type treatments on rusty metal, followed by primer and topcoat, only to have rust come through again. My next trial will be the Rustoleum or Corroseal/Rust Doctor type. Maybe the combination of rust converter and acrylic "primer" work well together? I am skeptical of rust covering silver bullets, but it's fun to try. One advantage of these dual rust converter/primers is that they can be used on surfaces that are part rust/bare metal/painted. The watery acid types state to only use on rusted surfaces and/or wipe it off non rusted areas.

Off topic, some 15 years ago I painted a 100% rusted metal T fence post with fish oil based Rustoleum rusty metal primer, followed with a rustoleum top coat. It's been outdoors ever since and is still about 90% rust free. http://www.hantover.com/specsheet_pdf/88387_Spec2.pdf


So which of the rust converter/primers are you thinking of trying?

 

[doitmyself]

Probably the Rustoleum tannic acid product, based on this test AND probably locally available.

The Coroseal and Rust Doctor seem to be very similar gallic acid products and would be next on the list, as they also have the coating/primer component.

If I was doing something or high importance or quality,I would do the correct procedure and sandblast (or other 100% removal), followed by proper preparation, primer, and top coat.

Again, based om my mediocre experiences (about a dozen), I don't think rust converters are a silver bullet.

 

[Donald]

I have a couple of rust spots on my 1999 pickup where the rust has been stopped in its tracks from the inside by Carwell, but I was looking at doing something easy on the outside.

I have tried Loctite Extend on s few things and it seems to do OK. But will be trying some Rust Reformer shortly.