Here you can see an old rusty motorcycle coil spring and some corroded nuts and bolts bathing in Evapo-Rust. (Image/OnAllCylinders)

Decades of advertising hyperbole have made us understandably hesitant to believe any “too good to be true” claim.

So when we saw that there was a product on the market that claimed to dissolve rust without any aggressive brushing or harsh chemicals, we were a bit skeptical.

But that’s exactly what Evapo-Rust says it’ll do—which means it could be a potential game changer when it comes to our metalwork, surface prep, and part restoration. Better still, EvapoRust says it is safe to the touch, doesn’t release any harmful vapors, and can even be re-used a few times.

Fortunately, our Honda CB350 motorcycle project gave us an excellent chance to put EvapoRust to the test. While we were rebuilding the bike’s forks, we noticed its external coil springs were covered in some mild surface rust and could use a bit of clean up.

How to Use Evapo-Rust to Remove Rust & Corrosion

When installed on the bike, the spring is shrouded by a plastic cover, but moisture was still able to get in to rust and corrode the surface of the metal. (Image/OnAllCylinders)

While we could’ve probably worked over the spring’s surface with a wire wheel and some Scotch-Brite pads, we hoped that Evapo-Rust would save us the hassle. So here’s how it went:

In order to work its magic, a part needs to be bathed in Evapo-Rust for a few hours, depending on how bad the rust is. So we took a large snack container, flipped it on its side, and filled the bottom with the rust remover. Then we plopped the spring in, where it was partially submerged in the rust eating liquid. A few hours later we checked back and rotated the spring slightly to cover more surface area.

In order to conserve our supply of Evapo-Rust, we only filled the bottom section of a sideways snack container, then turned the spring every few hours or so to ensure it got fully bathed.

This process went on over the course of a weekend, where we gradually rotated the spring so each side would sit fully in the Evapo-Rust rust remover for a few hours at a time. We inspected its progress with each turn too, as we excitedly watched the EvapoRust gradually eat away at the spring’s surface rust.

It’s worth pointing out here that Evapo-Rust won’t perform miracles. If the part is significantly corroded, don’t expect it to magically return to like-new condition. Evapo-Rust simply removes the surface rust and does not restore the underlying metal. The light surface corrosion on our coil springs here made them the perfect candidates for this test.

After about two days, we fully removed the spring and the difference was dramatic—the spring was virtually free of surface rust, with only very minor pitting remaining. We rinsed the spring off in our utility sink to remove any leftover Evapo-Rust residue (again, it’s non-corrosive and perfectly safe to handle the part), and poured the remaining Evapo-Rust from the big snack container back into its original jug, ready to be used again.

You can see that much of the rust is gone, leaving only trace hints of pitting and minor corrosion. (Image/OnAllCylinders)

Again, the spring only began with minor surface rust, but the results were still impressive. There was little to no evidence that rust was ever there.

We slipped the plastic spring isolators in so you could see the results a bit better. Here the treated spring (right) looks far better than the untreated spring on the left. (Image/OnAllCylinders)

But even after the spring was done, we knew that rust would likely return, so as an extra precaution to prevent the spring from rusting again, we hit it with Summit Racing’s spray rust preventer paint.

A couple of shots of black rust preventative paint will keep the springs from rusting in the future. We used black here because, when installed, the spring is hidden from view; a clearcoat would deliver the same results while retaining an original appearance. (Image/OnAllCylinders)

Does Evapo-Rust Work on Nuts & Bolts Too?

The Honda CB350 coil spring was a pretty large part, but Evapo-Rust works great for small hardware too—we found that out when we repaired an old snow thrower.

These carriage bolts, nuts, and washers held the bottom plastic blade on our snow thrower and, as such, were subjected to plenty of punishment. (Image/OnAllCylinders)
So, we plunked the hardware into a small cup of Evapo-Rust. (Image/OnAllCylinders)
Over the course of a few hours, the normally bright green Evapo-Rust changed to a muddy brown, hinting that its rust-removing magic was working. (Image/OnAllCylinders)
After a few hours in the Evapo-Rust bath, we removed the fasteners and rinsed them off, with similarly successful results. You’ll notice some leftover bits of road crud and paint that the Evapo-Rust won’t remove, but a few seconds with a wire brush took care of that gunk. As with the coil spring earlier, we hit them with some black rust preventer paint to keep ’em nice and clean once they’re back on the snow thrower. (Image/OnAllCylinders)

Evapo-Rust Comes in Several Sizes

For the price and hassle it saves, we keep a small supply of Evapo-Rust on-hand now, so it’s ready whenever we come across any mild surface rust.

Here’s a good comparison between new Evapo-Rust (left) and some used Evapo-Rust (right). The good news, is that you can just pour the old stuff back in the jug to use again and again, until the color turns really dark brown and it loses its efficacy. In our experience, we get three or four good uses out of it—your mileage will vary depending on the size of the part and the amount of rust you’re removing. (Image/OnAllCylinders)
Share this Article
Author: Paul Sakalas

Paul is the editor of OnAllCylinders. When he's not writing, you'll probably find him fixing oil leaks in a Jeep CJ-5 or watching a 1972 Corvette overheat. An avid motorcyclist, he spends the rest of his time synchronizing carburetors and cleaning chain lube off his left pant leg.