Buyers Guide: When to Use Rust Encapsulator VS. Rust Converter

Our tech team answers a lot of technical calls and emails each day, and there are a lot of common questions asked and advice given. Many of them are about when and where to use our different coatings and paints. Rust products might be the most confusing as far as when to use them and which one is correct for your rust situation. Obviously, you want the best way to remove rust from your barn find. But using the wrong product at the wrong time can increase the risk of not effectively treating the existing rust or creating new rust down the road.

We offer both rust encapsulator and rust converter for DIY automotive restorations. The question isn’t whether rust converters and encapsulators work. Both are very effective at preventing rust through the task they are designed for. The question is when to use rust encapsulator or rust converter to treat corrosion. They are two different products with different uses depending on the rust that is present. I decided to put together this quick Rust Treatment Buyer’s Guide to help you decide when you should use rust encapsulator versus rust converter.pencap4

Rust Encapsulator

Rust encapsulator is one of the oldest and most well-known products we sell. We’ve been an innovator in rust treatments, and this “paint over rust” product has stood the test of time. It seals rust in and stops it from spreading while acting as either a primer or base coat. Since the encapsulator has UV resistance, you can even leave it without a topcoat on chassis parts and wheel wells. In addition to the original formula, we also offer Rust Encapsulator Plus and Platinum for particularly tough corrosion fighting and longer-lasting protection.

Encapsulator is probably the safest and most universal of our rust products as it doesn’t much matter what it is applied over — it can even be applied to partially rusted surfaces. Below are some examples of situations where rust encapsulator is ideal and where another product may be better.

1.Surface Rust— Encapsulator will easily go over areas of surface rust and stop the rust from spreading. One medium coat usually covers light surface rust.

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2. Medium Rust — This is rust that is more than just surface or flash rust. It may have started to lightly pit the metal but hasn’t started to affect the rigidity of the metal. Start by wire wheeling or mechanically removing any loose rust and apply two or three medium coats of encapsulator to get complete penetration into the rust.

3. Bare Metal — Rust encapsulator can be used over bare metal, but I wouldn’t suggest it over epoxy or etch primer if you only have bare metal to deal with. It can be used to quickly seal bare metal in a pinch to avoid flash rusting as well.

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  1. Mixed Surfaces — Rust encapsulator is the best rust product to apply over surfaces that might vary in grades of rust or have a combination of bare metal and old paint present. If you have an area that you cleaned to bare metal or repaired and there’s still rust around that area, I’d suggest rust encapsulator.

Poor Uses for Rust Encapsulator

While rust encapsulator can be applied to almost any surface, it isn’t always the best option. Below are instances where we’d suggest a different product for the best results.

  1. Over Rubberized Undercoatings or Heavy-Duty Anti-Rust — Undercoating and Anti-Rust are great products for undercarriage or hidden areas on a vehicle, but using rust encapsulator over them is unnecessary and isn’t using the product to its full potential. I absolutely prefer to use it as a base under rubberized undercoating for peace of mind.
  2. In Hidden, Boxed or Hard-to-Reach Areas — Rust encapsulator needs some basic prep before application (wire brush loose rust and degrease with PRE Painting Prep). It also needs complete coverage to properly stop the rust, and it can be tough to get it to cover properly on an area that hasn’t been prepared completely. For hidden, boxed and hard-to-reach areas, we suggest our Internal Frame Coating.

Rust Converter

Rust converter is a coating that will convert heavily rusted areas into a protective polymeric coating with little prep. The resulting black surface is also fully paintable as a primer so you can directly apply paint and sealant without sanding or further prep. It is compatible with most top coats we sell and is popularly paired with Eastwood Chassis Black.

This product works well when used as directed. However, unlike encapsulator, it doesn’t have room for error when it comes to using it on incorrect surfaces. There has to be 100% rust present for rust converter to work correctly and to fully cure. The surface also needs to be top coated after it is cured. For the best protection, we suggest applying rust encapsulator over the converter and then applying the top coat.

When Does Rust Converter Work?

  1. Medium Rust — Areas that are completely covered in substantial rust are okay to use rust converter on as long as it isn’t mixed with bare metal or other coatings around it.


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  1. Heavy, Flaky Rust — Rust converter works best on rust that is heavy. This would be scaly rust that has begun pitting the surface and has covered all of the metal, such as in the image above. We still suggest knocking off the loose, flaking rust using a wire brush or wheel before applying the product. The goal is for the entire surface that is rusted to turn a purplish-black once the converter has finished curing. It may take two to four coats to fully convert a surface.

Poor Uses for Rust Converter

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1. Bare Metal — Do rust converters work on bare metal? That’s a big fat no. This product needs 100% rust present for it to work. In fact, virgin, clean metal could actually flash-rust if rust converter is applied and left on it.

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2. Mixed Surfaces — Again, rust converter needs 100% rust present for it to fully cure. This means it won’t work completely on areas that are a mix of rust and bare metal or a mix of original paint and rust. If you’re trying to treat small rust spots that have paint surrounding them (that we assume you don’t want to damage), you can use Fast Etch rust remover to saturate the area and get into those small rust spots. Then touch up with paint as needed.

3. Painted or Coated Surfaces — This product won’t work on bare metal areas to protect or prevent them from rusting. If applied to areas that are painted or used to coat for prevention, the rust converter won’t fully cure and the surface will stay sticky.

If you follow these quick guidelines, you can quickly determine if you need rust encapsulator or rust converter. Both can be purchased in our online Rust Solutions store, a brick-and-mortar Eastwood store or through our catalog. Each rust coating is available in sizes ranging from small aerosol cans to one-gallon cans and jugs depending on the severity of your project.

Feel free to drop us a comment if you’d like to see a Buyer’s Guide for any other product. Our other guides, along with demonstration videos, project walkthroughs and more, are available via the 24/7 Eastwood Garage home page. Eastwood has been a DIY automotive leader since 1978 and is committed to helping enthusiasts Do the Job Right.


  1. I hammered off what I think is paint over undercoating on my 15 passenger 2000 Dodge Van. It was on the frame and body. It flaked right off heavy flakes when hammered leaving a rusty surface. I also wire brushed it. I have a little frame extension rusted through in the far front and a little rust though of the floor by the rear wheels. I want to stop the rust. I drive on salty winter roads. I do have a HVLP spray gun/compressor. Also, what about brushing on bed liner after treating the rust? What would you recommend?

  2. Hi We would definitely suggest cutting out and welding in new metal in the areas that are actually rotted out and missing metal. For the other areas you can wire brush like you mentioned and hit it with our Rust Encapsulator and then follow it up with our Chassis Black or a bed liner like you mentioned for durability.

  3. How does your “internal frame coating” and “anti-rust in Amber” compare for treating enclosed box sections in a 35 year old car?

  4. When I have cleaned entire body down to bare steel and all rust is gone, what should I put on to protect from flash rust. Is ‘after blast” acceptable?

  5. I have a set of wheels that are about 80 years old, manufactured in England and used there until about 1972 when the car was shipped to USA. Wheels are wire spoked bolt-on with rims like a bicycle rim – edges are folded over (where the tire bead seats). This creates an inaccessible pocket around the circumferance of the rim. I hear loose rust flakes (possibly metal flakes from the vent hole that was drilled at manufacturing) within the voids. I have injected Evapo-Rust “rust remover” into the void of each wheel. Evapo-Rust “removes rust to bare metal” and “a rust eliminator” is their claim. I have never been sure if this is a “remover”, “encapsulator” or “converter”. What can you tell me about what I have done and what I should do to prevent further rusting of the wheel rims? Thanks.

  6. I have a replacement windshield frame for my ’69 Blazer. The inside of the frame is showing signs of rusting on the bare metal.
    I cant see a good way to get down into the frame to brush on anything to deal with the rust short of pouring something in and sloshing it around. Any suggestions and help are greatly appreciated.


  7. Very informative information about the various types of rust as well as products that work the best.
    Thanks for this

  8. Two questions.I have some pitted area around the back glass of my car. Some area are probably half way through the metal. What is the best thing to do to stop it? #2. I have some rust hole in the quarter panel. I was wanting to know if I crimp the panel and use panel bonding glue to attach the new metal. Then cover it with fiberglass and body filler. later down the road would it crack? Thanks

  9. The only correct way to repair those areas is to cut the metal out and replace it. Panel adhesive is good to use if you prepare the panel correctly. We’d suggest using good primer and body filler over fiberglass. A good repair will outlast the rest of the car.

  10. Hi Robert, you should be able to change your page view in the print preview feature when printing the page out. Hope that helps.

  11. Our internal frame coating works well for etching and sealing the metal, leaving a phosphoric coating. The Anti-Rust works best in areas that are already fairly clean. It does seal out moisture and will slow down pre-existing rust. I like to use the internal frame coating first to stop the rust and then the Anti-Rust as an extra barrier.

  12. The methods you have used is about the best you can do, that is a tough one without exposing the rust fully it is hard to completely remove it since it is so hidden.

  13. What if I coated most of the car with Rust-Oleum and the rust keeps coming back in patches, Any advice what rust control would work well with the patches of rust that comes back? I’ve used many products and finally seen good rust preventatives and stoppers but haven’t tried any until this summer.

  14. Hi Joe, your problem may be more an issue of hidden rust that the rust products can’t get to. If you only treat the surface and there is rust down below that it may come back. We’d suggest first sanding or wire brushing as much of the rust off as you can and then coming back with a few heavy coats of rust encapsulator to seal it up.

  15. What about places like windshield frames and A Pillars? I have rust inside and need to stop the rust. I do not know what all of the inside looks like as far as a mixed surface.

  16. Hi MattM, I’m fixing my 2000 Honda Civic Coupe driver’s side window which is stuck half down. While I’ve got
    everything all apart I thought i would think about rust prevention. Everything looks clean inside but I’m concerned about where the door skin is crimped on to the door frame. There is no visible flaking rust, just
    what seems to be a slight color change in the groove where the metals are joined when you look at it inside the door. The bottom inside edge of the door does show rust, the paint is lifted up and you can see rust. What would be the approach to deal with the inside and outside?
    Luann Casey

  17. Hey guys, hey I live in northern Michigan, I’m looking at buying a new truck in the spring. I want to be able to under coat it for salt protection, and I want to be able to coat the inside of the doors and cab corners and such areas with some thing to help with moisture and rust over time…. Wanted to know if and what products of yours would help me the best with these projects.. Thanks

  18. Hi Kevin, I’d first apply our Internal Frame Coating product to those areas and then follow it up with the Heavy Duty Anti-Rust for extra added protection. This combination has been the ultimate in neutralizing rust and sealing those hidden areas back up. Hope that helps!

  19. Hi Luann. That is a difficult one. The only 100% correct way to get into that area is to unfold the metal and clean the rust and apply rust encapsulator or an etch primer to seal the metal back up. The more realistic solution is to clean out any junk or flaky rust out of the inside of the door and apply our Internal Frame coating or Rust Encapsulator inside the door, focusing mainly on the seam where the door skin and inner structure touch. Our protects do have some ability to creep into the seams and will help stop and seal the rust issues. After that I would suggest applying our Heavy Duty Anti-Rust inside the door as well to give an extra barrier to any future moisture getting back down into the seam.

    Without seeing the door it’s hard to see how bad the rust has gotten, but this method will be the closest to unfolding the edge and cleaning the metal and then refolding. Hope that helps!

  20. Hi Richard, Our Internal Frame coating is the best bet for areas like that. It has a conical spray nozzle extension that will coat hidden areas. I’f you’re seeing rust bubbles or rust through the A pillar and windshield frame it already may be to the point of the metal being compromised. You can try tapping the small rust areas with a screwdriver pick lightly to see if it pushes through those areas. If it pushes through in those spots the metal has been compromised to the point of needing more than a chemical coating to repair. You can slow the rust down with our products, but at that point the correct repair is to cut the rust out and replace with new metal.

  21. I am redoing all my brakes on my 1978 Bronco and even tho I am replacing most of the hardware in my rear drums there are some internal components that need to stay such as the parking brake plate. It is all rusted so I submerged all the parts in evaporust to remove the rust but I am not sure what to use to prevent it from rusting again because these parts get really hot.

    How does rust encapsulator withstand high heat? Would Rust encapsulator work for drum brake components or even engine parts?

  22. Hi Hugo, Rust Encapsulator should up just fine as long as the brakes are gotten up to red hot (at which point you have bigger issues). We have used it on brake drum internal parts with no issues.

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