Question Re: sword straightening

[Utopianarian]

For those with previous experience and knowledge regarding consultation with whom can remedy a very slight bend in blade. The blade in question is a 28 inch katana with what appears like a slight bend in 2 places 3 inches apart from one another (monouchi) 6-7 inches from tip of blade. At some point somebody tried to straighten the blade I would assume which left the two very slight bends in blade. Hard to notice unless eyeing length wise and looking at reflective area on hada which shows slight wavering when light is cast upon affected areas. I would guess maybe <2mm deviations. I would assume a trained Togishi may be able to correct but generally from your knowledge and experience can this be done to a certain degree or completely if at all with such a slight bend. If this was left as is in your opinion would it affect the outcome obtaining high level papers at some point in the future from this prospective 

[Jacques D.]

I have already straightened quite a few blades, to do this I use this tool (see photo) after soaking the blade in hot water (60°C) for 2 or 3 minutes. You have to go very gradually and gently.

[Utopianarian]

Thank you Jacques. That does sound pretty straightforward but I am a little apprehensive being this would be my first attempt and not the best one to practice on. Togishi are 3-4 years wait. I did read one of the older threads on this board Re: straightening. The reason this has 2 bends I would think somebody already  made an amateur attempt. I do like to be self reliant on most things but just hesitant on this one. I think I need to think more about this one.

[PNSSHOGUN]

If the blade is good enough to consider high papers don't attempt doing it yourself, the risk of doing some sort of extra damage isn't worth it.

[Franco D]

Polisher !

 

2 hours ago, Utopianarian said:

high level papers

 

And, if the sword is really that good it should go through the hands of a well trained polisher anyway. 

 

Regards,

[Bruno]

I have a gendaito who was bent on several areas. Woody Hall in Las Vegas straightened it.

[Alex A]

Jacques, reading your instructions above, i cant help but wonder if it is totally necessary to add soaking in water into the equation 

 

I'm not advocating any DIY straightening. Would suggest not buying any blades with bends or if a tiny bend, live with it.

 

Could you not just put a towel over a not too hot radiator or heater and leave it there for a while ?

 

The thought of inexperience and "soaking in water" makes me cringe.

[rematron]

7 hours ago, Alex A said:

Jacques, reading your instructions above, i cant help but wonder if it is totally necessary to add soaking in water into the equation 

 

I'm not advocating any DIY straightening. Would suggest not buying any blades with bends or if a tiny bend, live with it.

 

Could you not just put a towel over a not too hot radiator or heater and leave it there for a while ?

 

The thought of inexperience and "soaking in water" makes me cringe.

I suppose it's too much to hope for that one would have the common sense to dry off a high carbon blade? 

[Alex A]

Hi Jeremy

 

Will explain.

 

Steel is porous, also, we don't know about the blade in question. Is it full of open grain?.

 

You may well think you have dried a blade off but that's where that story ends and where a thread about rust starts

 

Seen quite a few threads on here with regards folk not taking care of blades properly after a polish, which as you know allows water into the pores of the blade. 

 

Rust spots can appear within a very short time and stain the blade. Even read of blades arriving from the polisher with rust spots. Remember a real horror story where someone put a blade away after receiving it back from polish, forgot about it for a few months then had a real big issue.

 

My point was about inexperienced folk that may well be daft enough to think a blade is dry after submerging it in water for a few minutes, sheathing it, then dealing with the consequences.

 

Do a google, im not making it up.

 

As always, horses for courses. Just though worth a mention before someone does something they regret.

 

 

 

 

 

 

[Franco D]

It might be wise for NMB members to think carefully before posting "how to" information on this message board, where a novice with little or no experience and perhaps even less common sense happens upon this website who just by chance might be in possession of an art sword, decides to have at it. 

[rematron]

6 hours ago, Alex A said:

Hi Jeremy

 

Will explain.

 

Steel is porous, also, we don't know about the blade in question. Is it full of open grain?.

 

You may well think you have dried a blade off but that's where that story ends and where a thread about rust starts

 

Seen quite a few threads on here with regards folk not taking care of blades properly after a polish, which as you know allows water into the pores of the blade. 

 

Rust spots can appear within a very short time and stain the blade. Even read of blades arriving from the polisher with rust spots. Remember a real horror story where someone put a blade away after receiving it back from polish, forgot about it for a few months then had a real big issue.

 

My point was about inexperienced folk that may well be daft enough to think a blade is dry after submerging it in water for a few minutes, sheathing it, then dealing with the consequences.

 

Do a google, im not making it up.

 

As always, horses for courses. Just though worth a mention before someone does something they regret.

 

 

 

 

 

 

Oh, I believe you!  Just having a little fun. Cheers!

 

5 hours ago, Franco D said:

It might be wise for NMB members to think carefully before posting "how to" information on this message board, where a novice with little or no experience and perhaps even less common sense happens upon this website who just by chance might be in possession of an art sword, decides to have at it. 

Indeed!

[Jacques D.]

On 12/29/2022 at 10:16 AM, Alex A said:

Jacques, reading your instructions above, i cant help but wonder if it is totally necessary to add soaking in water into the equation 

 

I'm not advocating any DIY straightening. Would suggest not buying any blades with bends or if a tiny bend, live with it.

 

Could you not just put a towel over a not too hot radiator or heater and leave it there for a while ?

 

The thought of inexperience and "soaking in water" makes me cringe.

 

It's simple; a hot blade is softer than a cold one. 60° is the optimum temperature for straightening the blade (a polisher taught me how to do this) because it's hot enough but not too hot to take the risk of unintended softening ( correct?). Soaking the blade in water has no effect on it, polishers soak it constantly as they pass the stones and open the grits. Many people practice tameshigiri with nihonto (7 in my dojo) and sometimes they twist the blade so it has to be straightened.

 

[Alex A]

Hi Jacques,

 

What you or anyone else does with their blades has nothing to do with me, just making the point to seriously keep an eye on the blade afterwards, for a good while.  As mentioned, seen threads with regards rust staining after swords have been polished. If people want to treat their expensive arty swords the same as their bamboo choppers, then that's also their business.

 

If anyone does soak an antique sword in the bath tub and has issues, don't say you were not warned.

 

Remember, lots of people read here looking for tips, even overly eager beginners getting a little pedantic over a slight bend

 

Point made, 

 

Cheers.

 

 

 

 

 

 

[Franco D]

1 hour ago, Jacques D. said:

Soaking the blade in water has no effect on it, polishers soak it constantly

 

I don't know about the polisher of which you speak, however, all of the nihonto I have had polished have been returned with specific care instructions (both written or verbally) of how to oil the blade for the very reason that these swords have been exposed to water during the polishing process, which may have included straightening as well. Yet, no such mention from you. Just because we have been taught or shown how to do something does not automatically qualify us to teach others.

[Jacques D.]

I just said what I was doing, nothing more. I'm not forcing anyone to do the same. Now, when you know the underlying physics, you understand the processes better. A blade at a temperature of 60° dries faster than it cools.

Satisfied?

[Alex A]

Thinking about it, id say a lot depends on the blade Jacques. 

 

Can imagine something like a modern steel bamboo chopper drying out a lot faster than maybe an old koto blade that has its fair share of loose grain and small openings. Guess its not a one size fits all. I don't know how much water may be absorbed into a blade.

 

ps, how do you know your blade as reached the correct temp?, guess maybe you have some kind of thermocouple in your lab maybe?

 

Perhaps with a thermocouple folk wanting to heat the sword without the use of hot water could do, as mentioned earlier

 

Anyways, just thoughts, no physics expert here 

 

Cheers.

[Jacques D.]

Quote

Anyways, just thoughts, no physics expert here 

In that case, why issue an opinion that is obviously worthless?

 

Let's get back to the topic.

 

George,

 

 

Is the edge of the mune (if it is an iori mune) perfectly straight? If it is the case we can be in presence of "mura".  Mura is a slight declivity due to an error of polishing

[Alex A]

As mentioned, it may well prevent someone ruining a blade, surely as a physicist you can get your head around that and shouldn't go around giving out risky advice. As mentioned, not even any after care advice.

 

I'm no physicist, true, but know there are safer ways of heating expensive steel than dunking it in water.

 

Maybe you should do a search of rust/blades after polish.

 

Seriously, cant believe this topic has not been locked and a warning added in big red letters.

 

 

 

 

 

 

 

 

 

[Dave R]

32 minutes ago, Alex A said:

 

I'm no physicist, true, but know there are safer ways of heating expensive steel than dunking it in water.

 

Maybe you should do a search of rust/blades after polish.

 

Seriously, cant believe this topic has not been locked and a warning added in big red letters.

Soaking in hot water is actually one of the safest ways of heating a blade, controlled temperature, even distribution of heat, no heat staining to the blade. Aftercare the same as you would expect, dry it off while still hot, wipe down or spray with 99% isopropil alcohol and then a good dose of sword oil.

 Have I done this successfully myself, well yes, and with no problems, but with the caveat that it was a rather knackered WWII Showato of little value. Would I do it with a really valuable blade.... no, I know my limitations.

[Alex A]

5 minutes ago, Dave R said:

 Would I do it with a really valuable blade.... no, I know my limitations.

 

 

Hi Dave, il leave this subject with your last words, i certainly would not dunk anything i own.

[Andrew Ickeringill]

Straightening the blade is a crucial step of the polishing process, it can also be very risky, so many things can go wrong. Why would anyone advocate a complete amateur to attempt this?

 

No.

 

And to answer the original questions of this thread...

- Yes, even very slight bends can be corrected.

- By my definition of a slight bend, one or two shouldn’t affect paper levels, I’ve seen them in many a juyo and higher-level blades.

[lonely panet]

wonderfull words from a wonderfull person. 

 

ps, Andrew has straighten a odd bend for me in the past. masterfull results.