Does Rust Breed Rust?

[DerbyDad03]

A question entered my mind as I was sprucing up my utility trailer. I removed the strap hinges and closure brackets, etc. so I could clean off the rust, re-paint, etc.

There are lots of mating surfaces where rust was present on both surfaces, such as the back of the hinge plates and the trailer itself. I started wondering what would happen if I used a wire wheel to get the rust off one surface, but not the other. (That's not my plan, just my thoughts as I was working.)

All other things being equal (weather, moisture, etc) as they would be, does the mere presence of rust on one surface make the other surface more apt to rust?

[dpb]

DerbyDad03 wrote: ...

No. If anything, the rusty surface will tend to inhibit or slow down additional oxidation of the material as it tends to act as a barrier. Cleaning the rust layer off exposes fresh material to be oxidized.

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[dadiOH]

There is nothing in rust - iron oxide - to cause iron to rust as it is stable. However, rust is sort of porous and that means it could retain moisture and *that* would cause rust in the unrusted and unprotected surface.

[Blattus Slafaly]

Rust does protect metal and slows down oxidation but does not stop it. It's powdery and falls off then more oxidation occurs plus it absorbs water. Rust is the natural state of iron ore. Back in early earth history before oxygen, metal was dissolved in the oceans. As plants created oxygen all the metal rusted and fell out of the ocean into concentration that are now our iron ore mines. It's similar to when enclosed oceans dried up and left salt mines.

[dpb]

Blattus Slafaly wrote: ...

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[Norminn]

The surfaces would have to be clean and not exposed to air or water in order not to rust, right? A rusty metal coating would probably encapsulate small amounts of residual rust and so exclude air and water. Otherwise, rust will continue. Don't ask for sources.......just my logic at work :o) Now, if all rust is removed but differing metals are in contact then I think you get electrolysis. Never seen that, but it eats up some metals.

[salty]

Yes. Rust retains moisture.

[gfretwell]

The only rust that actually protects the metal is rust on CorTen steel, a special alloy

[gpsman]

Yep.

Rust Never Sleeps- Neil Young -----

- gpsman

[dpb]

[e-mail] wrote: ...

Not so...it will tend to slow down the rate of further oxidation on ordinary iron simply by providing barrier against oxygen to fresh surface. It's not perfect, granted, but it does have an effect.

It's relatively easy to demonstrate.

[Dan Espen]

Free oxygen in the atmosphere comes from plants. Scientists believe, before plants evolved there was no free oxygen in the atmosphere.

Sounds right to me.

[dpb]

Some of that's right, some of it isn't...

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[Frank]

Bluing or browning of firearms is controlled oxidation to protect the surface but you still need to keep oiled to prevent rust.

[aemeijers]

Chuckle. Learned that the hard way a few times. Prep the metal one day, get tired, figure I'll paint in the morning. Wrong. End up going over the whole thing again, even though the flash of rust was paper-thin. Rust Never Sleeps, indeed. Learned at a young age about waxing saw blades and table saw beds. Not much sadder looking than a rusty table saw.

-- aem sends...

[Dan Espen]

First you ask a question then you tell me the answer isn't right?

How do scientists know free oxygen increased in our atmosphere?

Beginning about 3.5 bya, banded iron ore deposits began to form underwater. Reduced iron (without oxygen) and silica washed into the ocean, combined with oxygen produced by algae, and settled together in banded layers. About 2 bya oceans saturated with oxygen released free oxygen to the atmosphere. Reduced iron no longer existed on the surface; banded iron ore deposits ceased to form.

[DerbyDad03]

re: Now, if all rust is removed but differing metals are in contact then I think you get electrolysis. Never seen that, but it eats up some metals.

I've seen it first hand. Back when the kids were babies, I had a Subaru. I belted the car seat into the back seat and gave it a tug as I always did. The seat belt bracket pulled right out of the floor.

The seat belt was bolted through the floorboard and into a plate on the under side of the car. I can't tell you what the 2 metals were, but they were definitely different. The plate pulled through the floorboard in the exact oval shape of the plate. There was no other rust any where in the area.

I took it all the way up to the regional manager for the North East with no satisfaction since the car was out of warranty (60K miles on it at the time). To them it was just a rust problem. To me, it was one hard stop away from my kid flying into the back of the front seat.

[Blattus Slafaly]

Rust does protect metal and slows down oxidation but does not stop it. It's powdery and falls off then more oxidation occurs plus it absorbs water. Rust is the natural state of iron ore. Back in early earth history before oxygen, metal was dissolved in the oceans. As plants created oxygen all the metal rusted and fell out of the ocean into concentration that are now our iron ore mines. It's similar to when enclosed oceans dried up and left salt mines.

[aemeijers]

Shoulda reported it on the NHSTA web site. I know smog stuff is covered to 100k by federal edict, I thought safety stuff was too. Seat belt mounting points tearing out of the pan definitely sounds recall-worthy to me. Now that I think about it, I had an 83 Mustang where the hardpoints for the front seat basically tore out of the pan, and the pan cracked at a fold point. But I just blacksmithed a hillbilly repair myself. (12 ga galvanized sheet metal plate over roofing tar, and peened bolts with big washers, through all the layers. Crude, but effective.)

-- aem sends...

[Phisherman]

The existing rust is likely a catalyst, but I suspect oxygen is much more important in making rust.

[Wes]

Well that is an interesting question, on my table saw, it sure seemed to. But then, I brown a rifle barrel and then oil it for protection.

I tend to think of rust as a sponge. Untreated it absorbs moisture, treated, it holds oil.

I have a feeling there are many opinions. Best to never let rust start.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller