I don't think zinc is involved to any great degree here. The blade is iron/steel with a number of impurities and has likely been heat treated. Heat treatment can make those areas darker when etched, owing to different crystalline structures and inclusions relative to the untreated areas. We have professional bladesmiths here who can probably give you a more complete answer.

Ian.

Hello Apolaki,

I doubt that the blade produces any really toxic fumes. It's most certainly not arsenic nor zink. (However, it is common sense not to sniff any fumes that smell bad, just to be sure...)

Steel with higher carbon content stains darker.
Hardened steel stains darker than the same steel unhardened, too.

Also, both are corroding faster than mild/unhardened steel.

The current state does not look that bad. In Jaw this would be fully acceptable (except for the splash of fresh rust which should be avoided by quick drying/oiling).

For a Moro kris, the metal surface should preferably be more shiny. It's a fine line between too shiny and no laminations visible and too strong an etch with a dull surface which just needs some experience to achieve. And even experienced folks here will retry the process several times to obtain a better result.

Regards,
Kai

Hello Detlef,

I beg to differ: There are several deep cracks which surely were filled with rust. There is no way that a gentle polish of the surface would have removed these pockets of residual rust. Thus, for long-term preservation a limited acid soak was not a wrong strategy; with good planning, the process could have been shortened though.

Hardly any harm done in this case - we all have seen much worse restoration attempts, I believe!

Regards,
Kai

Hello Apolaki,

Please try to answer those questions raised in post #18.

Regards,
Kai

Odor problem
 

Foul smelling liquids are often contaminated with bacteria and molds. Vinegar contains plenty of nutrients for microorganisms to grow in an aqueous medium. When you say it smells "rancid," I think you are referring to products resulting from microbial contaminants rather than a toxic gas being emitted from acid contacting the metal of the blade.

One possibility might be hydrogen sulfide ("rotten egg gas") if there is any sulfur in the metal. I've not heard of this being a problem with acid etching of steel/iron. Perhaps others have some more information on that possibility. Otherwise, I think your term "rancid" probably covers what is happening here.

Ian

Hello Kai,
I have polished several moro blades with a much harder grade of corrosion without a bath in a vinegar or citric acid solution before, not one of this blades show until now new active corrosion.
But in general I agree, it can't hurt! ;) I only want to state that it wasn't really required. And a more easy way would have been a direct polish.

For sure! :) So please don't push Apolaki to remove the hilt. Who get a small shock when he realize that he need to polish a blade (sorry Apolaki ;) ) will have a great problem to fix the hilt later again proper. All my Moro kris blades I have restored by self never I have dismantled the hilt, the result is in many cases visible at this place, just search a little bit.
Yes, it's a little bit circuitous to polish a kris blade with attached hilt but for sure more easy as to dismantle a hilt and more to reattach it proper again IMVHO.

Regards,
Detlef

By this pictures (taken from Gustav) you can see, how a kris hilt is constructed in many cases and I think Apolakis kris hilt as well. When the brass bands get broken when you want to dismantle the hilt you need to open the binding and you have a difficult restore object. It can be done but only for experienced persons.

Regards,
Detlef

Just a side note, Gustav's Moro hilt looks like it comes from Tawi-Tawi. Their hilts are made in this fashion.

Also Sajen is right - I've done a couple of Tawi-Tawi hilts before and it is a lot of work and time consuming.

Thank you Jose. When there is no compelling reason to dismantle a good fitted kris hilt I never would do it.

The hilt I've shown again with Gustavs pictures missing it's back crest, see picture. How you would classify the complete kris?

Regards,
Detlef