Does a polish fade by itself?

[piryohae3]

I know a polish can be ruined from frequent drawing and sheathing, but does it ever fade out by itself?

 

Thanks,

James J

[Ken-Hawaii]

You would have to ask a togishi to be sure, but I am not aware of any reason that would cause a polish to "fade." Steel is a pretty-durable metal, & without external influences like drawing & sheathing, & with no rust or corrosion, I'm fairly sure that a polish can last indefinitely. I've seen several blades that were temple offerings, partially unsharpened, with only their original polish, that looked brand-new after many hundreds of years.

[Rivkin]

Its an extremely tough question that sort of does not have a good answer.

There are some swords in major collections which were polished the last time during the early Edo period; they do not show pristine early Edo level polish, one can say they are completely out of polish.

 

Sciense-wise it can come down to question of how stable is a grain of martensite in a configuration where it sort of physically "sticks out of the surface".

Yet stability of martensite, probability of phase transition and thus ability to retain structure versus time is a highly arcane subject; In fact everything that comes down to real sciense of steel is an arcane subject, in part since its notoriously resistant to first principles modeling and its more or less clear we are talking about centuries in the least, i.e. beyond the practical lifetime of what is sold today.

 

There were even some (nonsense) analytical estimates that predicted that martensite and thus evidence of heat treatment actually disappears in 1000 years.

 

Kirill R.

[Jacques]

It can if you use Uchiko. Hadori is only a cosmetic process which can be wiped by a too strong cleaning.

[Jon MB]

Surely some sort of discrete patination is likely to occur over time, slowed by by oiling,  and only the abrasive features of uchiko will remove that patination, at the expense of the 'clarity' of the polish. Just a thought.

[IJASWORDS]

A polish by definition is the removal of surface defects like micro scratches. So any addition of surface scratches, corrosion etc after a polish will diminish the level of polish . 

[BIG]

Polisher Kenji Mishina polished 3 shin shinto swords, two of them made 1820 and one made 1848, some years ago. Now they are in a "fresh" polish. It is said, a good sword has to have a good polish, so maybe we have another kantei point, if it's not an attic found.

So if you are going to buy from a collector or dealer for a not low end or medium sword, buy a plolished sword.

After that, don't worry, be happy.

 

Best