Salt and Vinegar - Rust removal from cast iron

I'd be surprised if it didn't work. Steel is 98% iron after all. - GWE

"Grant Erwin" wrote: I'd be surprised if it didn't work. Steel is 98% iron after all. - GWE ^^^^^^^^^^^^^^ Furthermore, iron oxide is iron oxide, and that's what you're dissolving.

It worked for me. Degrease as well as possible before doing this.

Jim

More accurately, iron is 95% steel ;)

(Yep, it's weird like that...)

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Just don't try to de-rust spring steel. Gerry :-)} London, Canada

I don't see your joke. Maybe you are confusing "cast iron" with elemental Iron.

Thanks, Jim. I was hoping someone had actually tried it. I've got a relatively expensive casting I want to derust, and it was either the vinegar solution or beadblasting to remove the stuff.

Mike Eberle> >

Well, the average piece of 1020 mild steel is about 98-99% elemental iron. The remainder is mostly manganese and a smidge of carbon (0.2 +/- 0.05% is the specification). The average gray cast iron (iron now referring to the cast mixture rather than the element) has 1-3% silicon and 2-4% carbon. It can also have manganese, nickel, etc.

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Or -- electrolytic rust removal.

Enjoy, DoN.

Thus contradicting your own 'in' joke. Steel comprises 98-99% iron, as the OP said.

I've used both to good advantage. Honestly the electrolytic method does have an edge over the salt/vinegar approach, as the residue left behind is a bit less troublesome. Though it is somewhat more trouble as it requires a power supply, etc.

Jim

No, Jim. It means you have a good reason to buy a 12v battery charger to add to the tool collection.

Steve.

I have to agree. The iron used in making laminations for motors and transformers typically is carbon free.

Harold

The bead blasting offers a (minor) benefit due to the peening action, and will generally improve the surface, so given a choice between the two, if you're trying to improve the object, I think I'd choose the bead process.

Harold

Uh. My joke meant the composition "cast iron", which was in the context (machine tools are very, very rarely made of 99.9% pure iron).

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

The trouble with bead blasting is, solid metal is removes as well as oxide. For machine tools it's obvious to try to maintain as much accuracy as possible when doing this - as a very smart person once pointed out to me.....

The electrolytic method does not touch the unoxidised metal.

Jim

Chuckle!! Ok, I agree, assuming it's a machine tool he's talking about. If it's a rusty old water pump that he wants to paint for display, I might feel differently. He didn't really say. I'm not sure any of the procedures is as good as never having to deal with the problem in the first place.

Bead blasting is supposed to remove little to nothing from the base metal, but with cast iron I'm not convinced it doesn't. For certain it removes the free graphite from the surface. I know it has precious little affect on stainless.

Harold

molasses (say a cup) in a bucket of water also works well, if slow ( think a week or two...) and tends to be smelly.....

Leaves the cast completely clean back to grey, after a brush up. Will rust again though...

russ