10 Best Rust Converters (October 2026)

Rust converters go wrong in predictable ways. A buyer picks a single aerosol for a trailer frame and runs out halfway across the rails, or buys a gallon for one bracket and leaves most of it unused. Others treat the converter as a finished coating when the black, primed surface it leaves is meant to be painted. Loose scale and flaking rust also need to come off first, whatever the label promises. Best Rust Converters depend on three things: how much metal you need to cover, whether you want to brush, roll or spray it, and what goes on top afterward.

The short answer: the Corroseal Rust Converter, 1 Gallon suits garages, boat trailers and shops that want a water-based product they can brush, roll or spray. The Rust Kutter Rust Converter suits owners who want a quart-size bottle with a sprayer already included, and the Eastwood Rust Converter Aerosol suits restorers who need a 13 oz can for chassis parts and brackets. The rest of the list covers higher-coverage gallons, Rust-Oleum aerosols and two 35 oz black converter primers for truck frames and undercarriages.

TL;DR: top picks at a glance

• Best overall: the Corroseal Rust Converter, 1 Gallon, a water-based converter and latex metal primer rated for 200-250 sq ft per gallon.
• Best for sprayer-ready repairs: Rust Kutter Rust Converter, a 32 fl oz bottle that ships with a sprayer and also works with a brush, roller or spray gun.
• Best for aerosol touch-ups: Eastwood Rust Converter Aerosol, a 13 oz can that weighs 0.81 lb and needs no sanding, scraping or grinding.
• Best for large areas: FDC Rust Converter Ultra, a 1 gallon container rated for 500 sq ft of smooth, nonporous surface.

Best Rust Converters Comparison (October 2026)

#	Product	Best for	Size	Coverage	Format
1	Corroseal Rust Converter, 1 Gallon	Large projects	128 fl oz	200-250 sq ft per gallon	Liquid, water-based
2	Rust Kutter Rust Converter	Sprayer-ready repairs	32 fl oz	Not listed	Liquid with sprayer
3	Eastwood Rust Converter Aerosol	Chassis touch-ups	13 oz	Not listed	Aerosol
4	Corroseal Rust Converter, 1 Quart	Small projects	32 fl oz	200-250 sq ft per gallon	Liquid, water-based
5	FDC Rust Converter Ultra	Maximum coverage	128 fl oz	500 sq ft per gallon	Liquid
6	Black Star Rust Converter	Industrial steel	1 gallon	400-500 sq ft per gallon	Liquid
7	Rust-Oleum Stops Rust Reformer	Fast spot repairs	10.25 oz	Not listed	Aerosol, oil-based
8	Meuvcol Rust Converter Primer	Truck frames	35 fl oz	Not listed	Liquid, brush-on
9	Smaphy Rust Converter Primer	Undercarriage work	35 fl oz	Up to 100 sq ft per can	Liquid
10	Rust-Oleum Rust Reformer 3-Pack	Multiple rust spots	3 x 10.25 oz	Not listed	Aerosol, oil-based

1. Corroseal Rust Converter, 1 Gallon: Best Water-Based Rust Converter for Large Projects

• Size: 128 fl oz (1 gallon)
• Coverage: 200-250 sq ft per gallon at 8-10 mils wet
• Formula: Water-based rust converter with latex metal primer
• Application: Brush, roll or spray
• Weight: 10.2 lb

Pros:

• It converts and primes in a single step, so no separate primer coat is part of the plan.
• The formula is water-based and non-flammable, and cleanup needs only soap and water.
• Brush, roll or spray application covers both small parts and wide flat panels with one container.
• It is intended for marine, automotive, household and industrial work, which suits shops that handle mixed jobs.

Cons:

• The 200-250 sq ft per gallon figure is well below the 500 sq ft of FDC Rust Converter Ultra.
• At 10.2 lb, the gallon is more product than a single bracket or panel needs.
• Dry time and recoat window are not listed, so the container directions matter before topcoating.

Best for: Owners of trailers, boats and shop equipment who want a water-based converter and primer in one gallon container.

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What sets the Corroseal Rust Converter, 1 Gallon apart is its chemistry. It is the only water-based converter in this group that is described as a latex metal primer, which is why it can be cleaned from brushes and rollers with soap and water. The other gallon options, such as Black Star Rust Converter and FDC Rust Converter Ultra, do not state a base in the same way. The rust-treating step and the priming step happen together.

The stated coverage assumes an 8-10 mil wet film, which is a measured, fairly heavy application. That is how it reaches 200-250 sq ft per gallon, and it explains why the figure trails the 400-500 sq ft of Black Star. If your project is mostly large, smooth steel and coverage per container is the priority, FDC or Black Star will stretch further.

This is also the wrong choice for a one-off repair. For a small bracket or a single panel edge, the Corroseal Rust Converter, 1 Quart carries the same formula in a container that is much easier to store. Buyers who want a ready-to-spray can with no brush should skip to the Eastwood Rust Converter Aerosol.

2. Rust Kutter Rust Converter: Best Sprayer-Equipped Rust Converter for Car Bodies and Tools

• Size: 32 fl oz
• Weight: 2.76 lb
• Application: Brush, roller or spray gun
• Sprayer: Included
• Coverage: Not listed

Pros:

• A sprayer is included, so a buyer can start treating rust without sourcing a separate applicator.
• It reacts chemically with rust to form a stable black compound that can be painted over.
• It is aimed at car bodies, metal tools and outdoor equipment, which covers most garage rust problems.
• It is manufactured in the USA and offered in both quart and gallon sizes, so a repeat order can scale up.

Cons:

• Coverage per container is not listed, which makes it hard to size a project.
• The 32 fl oz bottle is only a quarter of the gallon containers in this list.
• Dry time and recoat guidance are not specified.

Best for: Hobbyists and garage owners who want a quart-size converter and a sprayer in one purchase for tools, bodywork and outdoor gear.

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The Rust Kutter Rust Converter is a practical choice because of the sprayer. Its closest rival by size is the Corroseal Rust Converter, 1 Quart, which holds the same 32 fl oz and weighs 2.6 lb against 2.76 lb here. Corroseal states its coverage and formula in detail, while Rust Kutter offers the included applicator and the option to move up to a gallon.

The product describes a standard converter process: the liquid reacts with the iron oxide and leaves a stable black surface that accepts paint. That makes it well suited to tools, fences and body panels where the finish will be painted afterward. Because it can also go on with a brush, roller or spray gun, the sprayer is a convenience rather than a requirement.

It is the wrong pick for anyone who wants a spec-driven decision on coverage. If you need a documented square footage, Black Star Rust Converter at 400-500 sq ft per gallon or FDC Rust Converter Ultra at 500 sq ft per gallon give clearer numbers. For quick, tool-free work on a small part, the Rust-Oleum Stops Rust Reformer aerosol is faster to set up.

3. Eastwood Rust Converter Aerosol: Best 13 oz Aerosol Rust Converter for Chassis Touch-Ups

• Size: 13 oz aerosol
• Weight: 0.81 lb
• Finish: Black primed protective coating
• Topcoat: Oil-based or water-based paint
• Warranty: 90-day limited warranty and 90-day return

Pros:

• It turns surface rust into a black primed coating without sanding, scraping or grinding.
• The treated surface accepts both oil-based and water-based paint, which gives flexibility on topcoat.
• The 13 oz can is larger than the 10.25 oz Rust-Oleum cans, and it weighs only 0.81 lb.
• It comes with lifetime tech support and a 90-day limited warranty, which is unusual for an aerosol.

Cons:

• Coverage per can is not listed.
• Eye, skin and respiratory protection are required, and the safety data sheet should be consulted.
• A single 13 oz can is limited to small parts, brackets and short frame sections.

Best for: Car and tractor restorers who need to seal surface rust on chassis parts and brackets without brushes or mixing.

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The Eastwood Rust Converter Aerosol is built around the aerosol format. A chemical reaction turns the iron oxide into a stable, sealed surface, and the spray can reaches awkward spots such as frame rails, suspension mounts and engine bay corners where a brush would be slow. Its 13 oz size is a step up from the Rust-Oleum Stops Rust Reformer, which holds 10.25 oz.

Where it differs from the Rust-Oleum cans is the focus on automotive use and the support behind it. Eastwood describes the product for cars, tractors, trucks and "barn find" chassis, and it ships with a return window and long-term technical support. That is useful for first-time restorers who want answers on topcoat compatibility.

Do not buy it for large surfaces. A single can will not cover railings, a full trailer or steel roofing, and it has no listed coverage to plan around. For that work, Black Star Rust Converter or FDC Rust Converter Ultra is the better fit. For several small spots on one project, the Rust-Oleum Rust Reformer 3-Pack gives more cans.

4. Corroseal Rust Converter, 1 Quart: Best Quart-Size Water-Based Converter for Small Repairs

• Size: 32 fl oz (1 quart)
• Weight: 2.6 lb
• Coverage: 200-250 sq ft per gallon at 8-10 mils wet
• Formula: Water-based rust converter with latex metal primer
• Dimensions: 9.8 x 3.6 x 3.6 in

Pros:

• It is the same water-based converter and primer formula as the gallon, in a quart that suits small jobs.
• Soap-and-water cleanup removes the need for solvents.
• The formula is non-flammable and non-corrosive.
• Brush, roll or spray application works on trim, fittings and small panels.

Cons:

• A quart treats only a fraction of what the gallon does.
• No sprayer is listed with it, unlike the Rust Kutter Rust Converter.
• Dry time is not specified.

Best for: Buyers with a small marine, automotive or household metal repair who prefer a water-based formula.

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The Corroseal Rust Converter, 1 Quart is the smaller sibling of the number one pick, and the choice between them is mostly about waste. If you only have a few square feet of rusty steel, the quart avoids buying more than you will use. It matches the Rust Kutter Rust Converter on volume, though Rust Kutter bundles a sprayer and Corroseal publishes its coverage and film thickness.

Skip the quart for anything larger than a few panels or a trailer frame. The 200-250 sq ft per gallon rating means a quart covers roughly a quarter of that, so the Corroseal Rust Converter, 1 Gallon or Black Star Rust Converter is a better fit for big projects.

5. FDC Rust Converter Ultra: Best High-Coverage Gallon for Railings and Machinery

• Size: 128 fl oz (1 gallon)
• Weight: 8 lb
• Coverage: 500 sq ft of smooth, nonporous surface per gallon
• Application: Sold as a rust repair spray
• Uses: Automobiles, machinery, railings, structures, tools and marine applications

Pros:

• The 500 sq ft coverage figure is the highest stated in this list.
• It converts rust to an inert coating that seals out moisture.
• It removes the need for sandblasting, grinding or scraping.
• At 8 lb, the gallon is lighter than the 10.2 lb Corroseal gallon.

Cons:

• The coverage figure applies to smooth, nonporous surfaces, so pitted or heavily rusted steel will use more.
• Application method and dry time are not described in detail.
• Finish color is not clearly specified.

Best for: Owners of railings, machinery and structures who need maximum square footage from a single gallon.

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FDC Rust Converter Ultra is the coverage leader on paper. Its 500 sq ft per gallon is double the upper figure for the Corroseal Rust Converter, 1 Gallon and edges past the 400-500 sq ft of Black Star Rust Converter. It is aimed at weather-damaged metal on automobiles, machinery, railings and marine hardware.

The caveat is the surface condition. The 500 sq ft figure assumes smooth, nonporous metal, so rough, pitted steel will absorb more product. If you want clearer application guidance, Corroseal lists brush, roll or spray with a film thickness. For a smaller project, the Rust Kutter Rust Converter is easier to handle.

6. Black Star Rust Converter: Best Polymer-Resin Converter for Farm and Industrial Steel

• Size: 1 gallon
• Weight: 8 lb
• Coverage: 400-500 sq ft per gallon
• Application: Spray, brush or roll
• Dimensions: 11.5 in tall x 5.5 x 5.5 in

Pros:

• Coverage of 400-500 sq ft per gallon is more than double the Corroseal gallon's stated range.
• It converts rust into a hard, black polymer resin coating that seals out moisture.
• It doubles as a paint primer, so the converted surface takes color directly.
• Spray, brush or roll application suits fences, metal roofs, grain bins, trailers and tools.

Cons:

• A gallon is more than most small repairs need.
• Dry time and recoat window are not listed.
• It leaves a black surface, so a color change needs a topcoat.

Best for: Farms, workshops and maintenance crews treating large steel surfaces such as fences, roofs and grain bins.

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Black Star Rust Converter targets industrial and agricultural users, with applications from farm equipment and sheds to trucks and trailers. Its polymer resin chemistry converts rust into a hard coating that also works as a primer. Compared with FDC Rust Converter Ultra, it gives a coverage range instead of one figure, and it lists spray, brush and roll methods outright.

It is not a match for small automotive touch-ups. A quart-size product such as the Corroseal Rust Converter, 1 Quart or an aerosol like the Eastwood Rust Converter Aerosol is easier to store and use for a single part. If the water-based formula matters, the Corroseal gallon is the one to choose.

7. Rust-Oleum Stops Rust Reformer: Best Oil-Based Aerosol Converter for Quick Spot Repairs

• Size: 10.25 oz aerosol
• Formula: Oil-based
• Dry time: Tack free in 20-40 minutes, 24 hours before topcoat
• Finish: Flat black
• Spray design: Any-angle, including upside down

Pros:

• It sprays from any angle, even upside down, which helps under frames and inside wheel wells.
• It is tack free in 20-40 minutes, the only fast dry time published in this list.
• It works on rusty surfaces, painted metal and bare metal.
• The oil-based formula bonds to the rust and leaves a surface that paints easily.

Cons:

• A 24-hour wait is needed before the topcoat goes on.
• A 10.25 oz can is small for anything beyond spot repairs.
• Coverage per can is not listed.

Best for: Drivers and homeowners who need to convert a few rust spots in awkward positions and want a quick, flat black result.

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The Rust-Oleum Stops Rust Reformer is the simplest product here to use. The comfort tip and any-angle spray mean you can treat the underside of a rail without twisting yourself around the can. Against the Eastwood Rust Converter Aerosol, it holds less (10.25 oz versus 13 oz) but publishes a dry time, which makes planning easier.

It is not the right fit for big surfaces, where cost in cans and application time add up. For those, Black Star Rust Converter or FDC Rust Converter Ultra works better. If you expect to treat several areas, the Rust-Oleum Rust Reformer 3-Pack uses the same formula in a multi-can set.

8. Meuvcol Rust Converter Primer: Best Brush-On 35 oz Converter for Truck Frames

• Size: 35 fl oz
• Application: Brush, in thin coats
• Coats: Minimum of two
• Dry time: 24 hours to form a protective film
• Finish: Flat black

Pros:

• It is a single-component, ready-to-use encapsulator paint, so no mixing is needed.
• It leaves a flat finish on both rusted and bare metal.
• It is positioned for automotive, truck, farm, industrial, marine and construction use.
• The 35 fl oz size sits between a quart and a gallon, which suits a frame or chassis job.

Cons:

• It needs at least two thin coats and 24 hours to dry.
• Grease and oil have to be removed from the metal before application.
• Coverage per container is not listed.

Best for: Owners of trailers, truck frames and car chassis who prefer a brush-applied black coating over an aerosol.

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The Meuvcol Rust Converter Primer is a converter and primer built for chassis and frame work. It is marketed as a heat-resistant rust neutralizer, and its instructions focus on a clean surface and thin coats. The two-coat minimum and 24-hour dry time make it slower than the Rust-Oleum Stops Rust Reformer.

Compared with the Smaphy Rust Converter Primer, which has the same 35 fl oz volume, Meuvcol does not publish coverage per container. It is the wrong choice if you need fast turnaround or a square footage estimate. For those needs, the Rust-Oleum aerosol or FDC's gallon fit better.

9. Smaphy Rust Converter Primer: Best Matte Black Converter for Undercarriages and Exhaust Parts

• Size: 35 fl oz
• Coverage: Up to 100 sq ft per can
• Finish: Matte black (also available in Gloss Black)
• Resistance: Heat and UV
• Topcoat: Not required

Pros:

• It converts and primes in one coat, with no grinding needed beforehand.
• A heat- and UV-resistant barrier suits road salt, coastal conditions and exposed undercarriages.
• Coverage is stated at up to 100 sq ft per can, which gives a planning figure that Meuvcol lacks.
• It is intended for chassis, brakes, engine bay, exhaust pipes, trailers, railings and lawn equipment.

Cons:

• 100 sq ft per can is a small area next to the gallon products.
• Application method and dry time are not described.
• The finish is black only, in matte or gloss.

Best for: Truck and trailer owners who want a documented coverage figure and a matte black finish for undercarriage and engine bay metal.

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The Smaphy Rust Converter Primer is a rust converter and premium primer in one can that does not require a topcoat. It also comes in Gloss Black for buyers who prefer a shinier finish. The heat and UV resistance fits exhaust parts and exposed chassis metal better than a general-purpose converter.

Its 100 sq ft per can is the limiting factor. For large surfaces, Black Star Rust Converter at 400-500 sq ft per gallon is more efficient. For fast spot repairs with a published dry time, the Rust-Oleum Stops Rust Reformer is the better pick.

10. Rust-Oleum Rust Reformer 3-Pack: Best Multi-Can Aerosol Set for Several Rust Spots

• Size: 3 cans of 10.25 oz each
• Formula: Oil-based
• Dry time: Tack free in 20-40 minutes, 24 hours before topcoat
• Finish: Flat black
• Weight: Not listed

Pros:

• Three cans give 30.75 oz of product in total, enough for several repairs on the same project.
• It uses the same oil-based formula as the single-can Rust-Oleum.
• It is tack free in 20-40 minutes.
• Any-angle spray technology works even upside down.

Cons:

• Coverage per can is not listed.
• The 24-hour wait before topcoat is the same as the single can.
• A three-can commitment is more than a single repair needs.

Best for: Owners with several separate rust areas, such as a trailer, gates and tool racks, who want one aerosol formula for all of them.

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The Rust-Oleum Rust Reformer 3-Pack is the same product as the Rust-Oleum Stops Rust Reformer sold as a multi-pack. The choice is simple: buy the single can for one repair, and the three-pack when several jobs are lined up. It converts rust into a flat black, paintable surface that is protected against future corrosion.

Do not buy it if you have one small spot to fix, because two of the cans may sit unused. For a larger single project, a liquid such as the Corroseal Rust Converter, 1 Gallon or FDC Rust Converter Ultra will be more economical per square foot.

Buyer's Guide: How to Choose the Right Rust Converter

The core trade-off is between convenience and coverage. Aerosols such as the Eastwood Rust Converter Aerosol and Rust-Oleum Stops Rust Reformer are fast and need no tools, but their cans treat small areas. Liquids in quart and gallon sizes cost more effort to apply but handle larger surfaces, and several publish coverage figures.

Before choosing, check these project details:

• Surface area: Estimate the square footage so you can match it against stated coverage, such as 500 sq ft per gallon for FDC Rust Converter Ultra.
• Rust condition: Loose flakes and scale should be removed, and heavily pitted steel will use more product than smooth metal.
• Application method: Decide whether you want an aerosol, a brush, a roller or a sprayer, since products differ.
• Topcoat plan: Some products leave a primed surface meant for paint, while others are described as needing no topcoat.
• Safety gear: Eye, skin and respiratory protection are advised on products such as the Eastwood aerosol.

Water-Based Versus Oil-Based Formulas

The Corroseal Rust Converter, 1 Gallon and the Corroseal Rust Converter, 1 Quart are the two water-based options. They are non-flammable and clean up with soap and water, which suits indoor shops and garages. They also include a latex metal primer, so the converted surface is already primed.

The Rust-Oleum Stops Rust Reformer and the Rust-Oleum Rust Reformer 3-Pack use an oil-based formula that bonds to the rusted surface. The trade-off is a 24-hour wait before topcoat, though they become tack free in 20-40 minutes. The other products do not state their base, so check the container directions.

Container Size and Coverage

Gallon containers give the most area. FDC Rust Converter Ultra is rated for 500 sq ft, Black Star Rust Converter for 400-500 sq ft, and the Corroseal gallon for 200-250 sq ft at 8-10 mils wet. These suit railings, roofs, trailers and machinery.

Smaller formats suit repairs. The Rust Kutter Rust Converter and Corroseal quart each hold 32 fl oz, while the Meuvcol Rust Converter Primer and Smaphy Rust Converter Primer hold 35 fl oz. Smaphy states up to 100 sq ft per can, and the aerosols do not list coverage.

Application Method

Brushing and rolling give control on flat steel and let you work the product into pitted areas. The Corroseal products, Black Star and Rust Kutter all support brush or roller use, and the Meuvcol is a brush-on product. For large panels, a sprayer speeds things up, and the Rust Kutter ships with one.

Aerosols reach tight spaces. The Rust-Oleum cans spray from any angle, which helps under frames and inside wheel wells. The Eastwood can suits chassis parts and brackets where a brush would be slow.

Surface Prep and Topcoat Planning

Most converters work best after loose scale is removed, and grease and oil should be wiped away before application, as the Meuvcol directions stress. Wire brushing throws off sharp flakes, so a pair of welding gloves protects your hands during prep. Eye and respiratory protection matter with aerosols.

For the finish, the Eastwood surface takes oil-based or water-based paint, and Black Star works as a primer for color. Where the steel is deeply pitted, a high build primer can level the converted surface before the final coat. The Smaphy product is described as needing no topcoat, though a painted finish may still be your preference.

Frequently Asked Questions About Rust Converters

What Does a Rust Converter Actually Do?

A rust converter reacts chemically with iron oxide and turns it into a stable, black compound that can be painted. Products such as the Rust Kutter Rust Converter and Eastwood Rust Converter Aerosol work this way on surface rust. It is not intended for thick, flaking scale, which should be removed first.

Do I Need to Paint Over a Rust Converter?

Several converters leave a primed surface that is meant to be topcoated. The Eastwood Rust Converter Aerosol accepts oil-based or water-based paint, and the Rust-Oleum Stops Rust Reformer requires a 24-hour wait before topcoat. The Smaphy Rust Converter Primer is described as needing no topcoat.

How Much Surface Does One Gallon Cover?

It depends on the product. FDC Rust Converter Ultra is rated for 500 sq ft of smooth, nonporous surface, and Black Star Rust Converter for 400-500 sq ft. The Corroseal Rust Converter, 1 Gallon covers 200-250 sq ft at 8-10 mils wet.

Can I Use a Rust Converter on a Car Chassis?

Yes, several products are aimed at chassis, frames and undercarriages. The Smaphy Rust Converter Primer and Meuvcol Rust Converter Primer are both sold for this work, and the Eastwood aerosol is designed for car and truck chassis parts. Clean off grease and oil first, and apply thin coats where the directions call for them.

Is a Water-Based Rust Converter as Good as an Oil-Based One?

Both types convert rust and leave a primed surface, and the choice comes down to handling. The Corroseal Rust Converter, 1 Gallon is water-based and non-flammable with soap-and-water cleanup. The Rust-Oleum Rust Reformer 3-Pack is oil-based and bonds to the rusted surface.

Should I Buy an Aerosol or a Liquid Rust Converter?

Buy an aerosol for small, hard-to-reach repairs, and a liquid for larger surfaces. The Rust-Oleum Stops Rust Reformer sprays from any angle, while the Black Star Rust Converter treats 400-500 sq ft per gallon. If you want a liquid in a small size, the Rust Kutter Rust Converter includes a sprayer.

Final Verdict: Which Rust Converter Should You Buy?

Best Rust Converters for most buyers start with Corroseal Rust Converter, 1 Gallon: it is a water-based converter and latex metal primer rated for 200-250 sq ft per gallon, with brush, roll or spray application and soap-and-water cleanup. Its main weakness is coverage per gallon, which is well below FDC and Black Star, and it has no listed dry time. For mixed marine, automotive and household work, it remains the most versatile choice here.

For alternatives by use case, the Rust Kutter Rust Converter suits owners who want a sprayer included, and the Corroseal Rust Converter, 1 Quart suits small water-based repairs. The Eastwood Rust Converter Aerosol is the pick for chassis touch-ups, while FDC Rust Converter Ultra at 500 sq ft per gallon and Black Star Rust Converter at 400-500 sq ft per gallon suit large surfaces such as railings, roofs and machinery.

For specialist jobs, the Rust-Oleum Stops Rust Reformer and Rust-Oleum Rust Reformer 3-Pack give fast, tack-free results in 20-40 minutes for awkward spots. The Meuvcol Rust Converter Primer and Smaphy Rust Converter Primer target truck frames and undercarriages, with Smaphy publishing up to 100 sq ft per can. If you are still undecided, measure the area first: choose a gallon for anything over a few hundred square feet, and an aerosol for anything smaller.