Information about first antique tanto and kogatana

[Haon]

So, a few months ago I got this "old" tanto in a bad shape. It has a severe chip on the edge the polish is more or less scratched, one scratch is fairly long and well noticeable, the others are really fine, and even in person hard to see. 

As general information, it has a motohaba of 28,4mm and a motokasane of 6,9mm, the nagasa is 22,65cm, with a saki-sori of roughly 5-6mm. The blade itself is mumei, and has a slight amount of niku. The habaki fits very well and seems to have been made for the blade, it is a genuine "double"-habaki made out of two pieces, and copper if I had to guess, as this has some small pieces of verdigris on the inside.

The second one is a little signed kogatana, which I acquired shortly after the tanto, and I am curious to know if the signature is genuine, given the bad shape it is in. It is 2mm thick, 12,6mm wide, and has a nagasa of 11,8cm.

 

I hope to get an age estimation for both, maybe eben an estimate on quality. Generally, just some more information than the nothing I know currently. Maybe one or both are worth getting restored if possible, or is there a possibility to get both estimated professionally? I live in Germany, if this helps.

 

Also, no, I won't touch either of this with anything than a cotton rag and oil. 

[Nihontocollector752]

I might be really wrong here but this looks more like a katana thatbwas broken and formed into a Tanto. I would like to see what Tanto collectors say on this one....

[Brian]

I was just thinking that something about the sugata just seems very off. More of a gut feel.
I think this might have been much longer at one point. Mayble/likely a broken blade with a new nakago crudely done. Possibly naginata or nagamaki?
But at least it's genuine. So is the kogatana, although signatures are usually more decorative than real.

[Haon]

Thank you very mich for you input. The point of a broken blade would explain to me why the shinogi-ji changes so early after the habaki. Maybe also the chip in the blade. 

Regarding the kogatana, maybe someone can translate the name (if it is one)? It seems to have rusted far less heavy at the ha, so maybe it is a laminated construction, or it has a, now hardly to make out, hamon. Seems that way, the steel should rust less if it has a smaller grain structure.

[mas4t0]

9 minutes ago, Haon said:

Thank you very mich for you input. The point of a broken blade would explain to me why the shinogi-ji changes so early after the habaki. Maybe also the chip in the blade. 

Regarding the kogatana, maybe someone can translate the name (if it is one)? It seems to have rusted far less heavy at the ha, so maybe it is a laminated construction, or it has a, now hardly to make out, hamon. Seems that way, the steel should rust less if it has a smaller grain structure.

 

Derek,

 

Why would you expect the steel to rust less if it has a smaller gain structure?

 

My understanding is exactly the opposite; that a smaller average grain size will make the metal more susceptible to corrosion.

 

Grain boundaries are like surfaces, and show higher reaction rates compared to the inside of the grain. The finer the grain structure, the greater the amount of grain boundary and the greater the level of corrosion.

 

This is readily apparent during etching, where grain boundaries are etched to a greater extent, revealing the grain pattern.