Altering to oxide stale of iron oxide.

[Justincase]

I hope you do not mind me asking a none gold orientated question.
But it involves the alteration of iron oxide from its lower red state to its higher black state.
Fe2O3 to Fe3O4
I have always undertaken the restoration of antiques as an easy way to add value to an investment.
But on occasion I am hampered with this process because the only method I am familiar with to achieve this change in oxide state is the use of steam.
For this I normally have to be capable of the disassembly of the item in order to preserve any material that would be adversely affected by this process.
Unfortunately some items can not be dissembled but still need the rust to be stopped, and preferably the black haematite patina left in its place.
Is there any way to achieve this in a manner which could be controlled enough not to affect delicate organic material in its close proximity.
This would help me treat small iron parts which resist stripping form woodwork, and with a nice Napoleonic era sword I am just starting to plan for.

 

[Lino1406]

Did you consider conc. NaOH at 200C. This is called blackening

 

[Justincase]

Did you consider conc. NaOH at 200C. This is called blackening

No, I do not try and artificial create a finish as in alkaline oxidation blackening in a preservation.
Sometimes if I fabricate a new part that should stand out as a replacement I will finish it in such a manner, but I do prefer Philips Professional Cold Blue instead.
Also, if distilled water at 100c would be destructive to delicate organic matter that is closely situated, I would hate to see what NaOH at 200c would do to it.

 

[kurtak]

No, I do not try and artificial create a finish as in alkaline oxidation blackening in a preservation.
Sometimes if I fabricate a new part that should stand out as a replacement I will finish it in such a manner, but I do prefer Philips Professional Cold Blue instead.
Also, if distilled water at 100c would be destructive to delicate organic matter that is closely situated, I would hate to see what NaOH at 200c would do to it.

because of the underlined -"cold bluing" is going to be your only option (at least as best as I know of)

The trick is going to be protecting the organic (wood, leather etc.) during the cold blue chem process

If it were me I would (first experiment) by taping off the iron part - then seal the organic part by melting some bees wax & pouring it on the organic part (some wax will end up on the "taped" iron part) - then using a razor blade cut the wax between the organic & the iron so that the wax can be removed from the iron by pulling the tape

You should then (at least in theory) be able to cold blue the iron without having much if any bleed over of the cold blue chems to the bees wax sealed organic material - then you can remove the wax from the organic part

For what it is worth - I have cold blued 6 antique guns over the years - all of them turned out with a VERY nice "antiqued patina" that improved their value - two of those guns hang on my living room wall as they were given to me by my grandfather when I was a young man - the other four I bought to restore & sold

of course when cold bluing the guns all the organic is first removed so not sure the above would work - just my thought on what I would "try"

Kurt

 

[Justincase]

Thank you, that is a good idea.
I am in the process of picking the brain of the people at the Royal Albert Museum to see if there are any safeguards I should put into place before going forward with the Prussian cuirassier pallasch, it was issued to the 5th Regiment of Prussian Cavalry and was likely involved in the fight against Napoleon. It is sometimes called the "Russian" or 1819 model and is not very commonplace.
I also have a bit of a weakness for The Martini Henry and their close relatives, but affordable parts and examples in need of help are also quite hard to find.

 

[jimdoc]

You could go on Weaponsguild.com (you would have to join) and ask over there. They should be able to help, and give advice to not destroy the value of the items.

 

[Justincase]

You could go on Weaponsguild.com (you would have to join) and ask over there. They should be able to help, and give advice to not destroy the value of the items.

I am a member of a few groups, but if you happen to know a bunch of metallurgical chemists, it would be silly not to ask them for help.
You never know, we might come up with a new method no one else has thought of.

 

[FrugalRefiner]

Check Lou's signature line for a link to sciencemadness.

Dave