IRON/STEEL OXIDIZATION OR FINISHING?
 

Hello guys, i would discuss a question with you, if you are interested.
Often when we buy a white weapon, especially on Ebay, we receive at home a sword or a dagger that is rusty and so we clean the blade from rust, but after this we can find that the blade is black. Now, and i speak especially about african weapons because is the field that i know, in many good books the authors write that african blacksmiths embellish the blade giving a burnishing by burning palm oil, and the blackened finish will never loose its color. My question is: the black on the blades is always a burnishing, or the iron/steel oxidization can provokes this result? In other words, could the black color be a fase of iron/steel oxidization (and so the rust a second fase)? And if that is true how we can distinguish the two cases?
Thank you to everyone who wants to participate.

Hello Flavio, A good question. I have old 19th cent pictures of weapons shining in the sun, so some were obviously shown off clean and bright but that is not how collectors want them, strangely if it were a cavalry sabre parade clean is disired. The black from cleaning a white weapon is I think, oxidization and a small amount of etching action by rust. I personelly have not seen blackening by application only from the use of the natural iron scale produced in the forging of the metal this like decorative blueing on military fancy swords offers protection from rust. You will see on your pieces that where the iron scale is left on or used to decorate the piece there will be very little if any rust. The iron scale may be made to shine with the application of some substance but that is not what makes it black. I hope I have not taught your grandmother how to suck eggs :D You might not understand that ;) Tim

Flavio, blackening can be two things:

1. when steel is etched with acid, it can turn black, especially if it has been tempered. Tempered portions tend to turn black in the presence of acid.

2. when steel is older, the oxidation can create a patina on a blade. This surface patina can turn a brown-black, which means it is stablized oxidation.

3. when rust is present and it becomes stabilized, it can turn black, again a sign of stabilization.

Hope this helps.

Thank you Battara, this is of great help, but as i said on african weapons the blackening is also made by burning oil palm. One can distinguish this case only as Tim says: the piece there will be very little if any rust? or the the oil burnt give a more shining finishing?
Thank you