Black rust

[Greybeard]

I encounter this problem for nearly 40 years -- first with my early Colt automatic pistols, now with some of my keris blades: spots of black rust!

While red or brown rust usually comes off easily, black rust is very hard and very stubborn and seems almost impossible to remove. Is there any method to get rid of those ugly black rust spots? Any suggestion will be appreciated.

Regards,

Heinz

[sirek]

Black rust is caused by iron impurities that leaves too much sulfur behind
what causes the black spots.

I myself have tried various attempts to remove rust
(See the topic: cleaning the blade)
I had at that time only a blade with brown rust, but maybe this is a solution?

or you can try with :Oxalic acid

[kronckew]

found this:
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A simple and inexpensive way to remove rust from steel surfaces by hand is to rub the steel with aluminium foil dipped in water. Aluminium has a higher reduction potential than the iron in steel, which may help transfer oxygen atoms from the iron to the aluminium. The aluminium foil is softer than steel and will not scratch it, as steel wool will, but as the aluminium oxidizes, the aluminium oxide produced becomes a fine metal polishing compound.
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seems worth a try

p.s. - black iron oxide is an alternative form of rust to the more destructive red rust we all hate. rust bluing is/has been used to produce a nice blue/black protective coating on steel, and the black ferrous oxide coating is somewhat protective against red rust, and is the major component in the patina steel aquires over the years. removal of black rust or patina from antiques may lower their value.

[A. G. Maisey]

Aluminium foil in warm soapy water is the easiest way to clean silver cutlery --- beats silver polish any day of the week.

[Greybeard]

Sirek, Kronckew, thank you both for your suggestions.

p.s. - black iron oxide is an alternative form of rust to the more destructive red rust we all hate. rust bluing is/has been used to produce a nice blue/black protective coating on steel, and the black ferrous oxide coating is somewhat protective against red rust, and is the major component in the patina steel aquires over the years. removal of black rust or patina from antiques may lower their value.[/QUOTE]


I think it will be best to leave the "black rust" alone and just plane off the high spots with a brass scraper. My home-made brass tools have always been very useful for a gentle (red/brown) rust removal without harming the patina.

Heinz

[kulbuntet]

dilute vinegar

[Greybeard]

Originally Posted by kulbuntet

dilute vinegar

Thank you, Kulbuntet. Would grapefruit juice or pineapple juice also help? Seems less aggressive to me than vinegar.

Regards,

Heinz