If you are in possession of a Japanese sword or set thereof, and are not simply 'dumped' with an unwanted weapon via unconventional means, it is very important that you know exactly how to take care of your sword. Although the advice below is applicable to swords of most eras, provenances and styles, my expertise extends very specifically to swords from the region of Japan and to a lesser extent China, therefore this writeup will be similarly focused.

Care of a sword is far from an easy task, and is seen by many owners as the greatest downside to sword ownership. Whereas there are a great many people who would (for a variety of reasons) wish to own an ancient and powerful blade with histories all its own, there are a great many less willing to clean, oil, and maintain the sword and its fittings as often as once in a month. Although waving a large piece of sharp metal around may feel formidable and even makes some people feel safe and secure, this blade will quickly become a rusted and useless shadow of its former brilliance, rather than the piece of history it is, if not cared for in a proper and diligent manner.

If there is one single menace (rather than the multitude that exist in reality) that the replica sword industry has unleashed upon the field of sword forging, fighting and collecting, it is the belief that all swords are made equal. By this I mean that newcomers to the field are often armed with a variety of knowledge about swords in general when they attend their first sword show, but it is in general the wrong knowledge for the task. Replica swords are constructed from stainless steel or aluminium/zinc alloy, metals unsuitable for blade construction but crucially are both highly visually attractive and extremely resistant to corrosion. Such display-only blades would shatter immediately in combat and cause serious injury to the wielder and his opponent, but in the brief seconds they were intact they would gleam and flash in the light just like swords in the movies. There is a very direct link here in that the film industry actually spawned most of the replica sword industry; modern display swords are designed upon wisdom gained by prop departments making stage swords for the theatre and film.

The result is that whereas in days past a newcomer would seek out knowledge in books to better understand the weapons that so fascinate them, now there is a seemingly vast body of knowledge immediately available in the form of replica swords and their attendant accessories. It is a fact that a large majority of sword collectors admit to buying a replica sword as their first weapon, due to the their low price and (apparent) beauty. Stainless steel swords in particular possess a high mirror shine which requires almost no care to maintain other than avoiding scratches and knocks. Genuine swords however, are far more fragile, and applying knowledge gained from ownership of replica blades can be fatal to an otherwise artistic and valuable blade.

Identifying your sword

The first and most important step is to identify what kind of sword you own. Although not strictly part of this writeup's topic it is still vital information, as improper cleaning can and will destroy any sword. This is of great use to those who have received one or more blades via inheritance or generosity and are now at a loss as to what to do with them. If you are already fully aware of your blade's properties then please omit this section. All swords possess certain characteristics in their appearance and shape that allow identification of their origins, and are summarised below;

Blade surface
Most important is the appearance of the blade itself, as it takes a highly advanced replication process to construct an authentic-looking blade of inferior materials, which is generally too expensive for replica manufacturers to consider. The greatest giveaway of a replica sword is a mirror-like finish to the blade surface; stainless steel can be polished to a high mirror shine in which you can quite literally see your face, whereas genuine swords constructed of high-carbon steel tend to be duller, greyer, and have a great deal of activity within the blade. By activity I mean what would first appear to be imperfections in the steel; Japanese swords are forged by an ancient process known as pattern welding, which repeatedly folds several layers of steel over and over to create a more homogenous blade. This creates great variation in the appearance of the blade steel, which may actually make the blade appear amateurish or of lesser quality than a nice shiny stainless blade. Another identifier is the appearance of a hamon or temperline; this should appear as a line of some variety on the steel itself, roughly one quarter-inch from the cutting edge, and is the result of differential tempering. A genuine hamon will look like a transition from a lighter to a darker metal, a fake hamon (usually sanded or acid etched onto a plain blade) will look like a foggy version of the rest of the blade, and most likely be a highly regular sine wave pattern. Also, look for rust on the blade; stainless steel is called stainless for a reason in that it does not rust quickly or easily. Perhaps the most important thing to look for is a signature or inscription on the tang, which would indicate a blade of traceable history which may be over a hundred years old. If such an inscription is found (in Japanese characters, English characters are extremely rare even among Western smiths) it is highly advisable to take the sword to an expert and have its origins traced.

If the blade is either indistinct or perhaps too mistreated, identification by the blade alone may not be possible, therefore other features must be examined. The fittings of the blade, also called the furnishings, include the handle, the saya (scabbard or sheath), and their component parts. Fake fittings are more difficult to spot than blades, but it can be done. The first thing to check is the handle; a genuine sword will be attached to the handle by one or more bamboo pins called menugi-ana; replicas almost universally omit this step and simply glue the blade into the handle, secured at the bottom with a nut. Similarly, any attempt to dismantle a replica sword will probably fail as they are simply not designed for it, whereas genuine swords must be dismantled for cleaning, the eventual point of this writeup.

Please note that Japanese swords come in a great variety of bladeforms; as such I would advise reading Styles of Japanese Swordmaking or a more comprehensive book on the subject if you own a blade of unfamiliar appearence.

Maintaining the Sword

At last, we come to taking care of your sword. This section makes the assumption that you have a genuine sword; if you have an alloy or stainless blade then congratulations, you will likely never need to clean your blade. However, sword cleaning for the owner of an ancient or at least properly made battle-ready sword is a never-ending battle against moisture, acid and dust. As melodramatic as this sounds, after a year of sword stewardship (as opposed to ownership) you will see what I mean. The ancient samurai believed themselves to be merely custodians of a sword, preserving its beauty for future generations of their family; thus they were far more willing to expend hours per day on the blade upon which their life frequently depended than we are today. However, due to proper care many of the swords of those samurai are still preserved today. This section also assumes that your blade is in relatively good condition; if the blade is corroded and/or damaged, it is recommended that you take it to a trained sword restorer. Do NOT take it to a general antiques restoration shop, as such places have a long and bloody history of applying standard metal cleaner to ancient swords, and consequently ruining them forever. The steps outlined below should be performed roughly once per month for a standard sword. You will require the following tools and supplies:
  • Choji oil
    This is an oil mixture of 99% mineral oil, 1% clove oil. If this is not available, pure mineral oil or some non-corrosive gun oils are acceptable, such as Remington. Do not use any form of vegetable oil, as they are chemically active and will 'gunk up' over time and damage the scabbard. Choji oil has been used for hundreds of years, and remains the best option.
  • Uchiko Powder
    Uchiko powder is made from the stones used to sharpen and polish Japanese swords, ground up into a fine white powder and contained within a silk or cotton ball. There is no acceptable substitute for uchiko powder, although it is thankfully far more widely available than in the past.
  • Tissue paper
    Although a somewhat obvious item, it is necessary to make certain that the paper you choose is both soft and as lint-free as possible. Avoid scented or otherwise impregnated tissue, as the chemicals within them attack blade steel. Similarly, recycled tissue can cause more harm than good, as its composition and roughness are highly variable. Human skin heals, steel blades do not.

Before performing sword maintenance, it is necessary to properly prepare the blade. Remove the blade from its scabbard and fully dismantle and remove all the fittings; you should be left holding the blade only. How you hold the blade is up to you, but I would recommend laying it edge-out over your knees while cross-legged, or for the more safety conscious lay it on a clean desk or surface. Carpet is a pretty bad idea.

You must remove all of the old oil from the blade surface before re-applying any new oil, or gaps will appear when the old oil finally evaporates. This can take up to two months, but will leave sections of the blade completely unprotected. Take some tissue paper, and fold it over a few times into a wad. Wrap this wad around the blade, on the unsharpened edge, and slowly wipe from handle to tip, applying gentle pressure to both sides. Repeat this until no oil is visible, using a fresh piece of tissue each time.

A close inspection for signs of rust or damage must be performed each time the blade is dismantled, as it is not uncommon (particularly among martial arts blades) for scars and burrs to form on the blade, in which rust finds a home very quickly. Similarly, it is at high-stress points such as the ‘sweet spot’ (point of harmonic resonance on the blade) and the tang (the part of the blade that extends down into the handle) that stress fractures or points of weakness form, from simple metal fatigue. Look for flare-ups of rust, which if caught early should simply wipe off during cleaning. If it is more persistent it may require more rigorous cleaning with uchiko powder, and in the worst case the attention of a professional polisher. Points of weakness occur where the crystalline structure of the steel develops a fault, and are visible as areas where the blade looks twisted or distorted somehow, usually in linear structures. This could be the death of the blade; upon discovery of such artifacts immediately seek consultation before using the blade again. Similarly, while scratches are merely cosmetic and can be ignored, burrs or nicks in the blade can be extremely dangerous to use. Burrs in particular are very dangerous, as they can cause serious damage to both swordsman (they can slice skin with ease) and sword if they go unnoticed for any length of time. Once again, professional consultation is recommended.

However, most likely none of these will be discovered, at most some mild rusting will appear on the blade surface if it is well-looked after. The first step is to apply the uchiko powder; as it is made from the finest stones used to polish swords it is mildly abrasive, so be careful not to rub too hard or you may destroy the polish already present. Take the ball (you will notice that uchiko powder is only available bound in a ball) by its handle, and firmly tap the blade all the way along. Depending on the construction of the ball, this will release either a small or large amount of powder, so adjust accordingly. You are aiming for a fine, barely visible even coating along the blade. Ensure that you apply powder to the tang also, as neglecting this can cause rust to ‘creep’ up out of the handle whilst the blades are in storage, which can fast become a serious problem. Once you have applied the powder, wipe gently, again from tang to tip. If there are any small stains or clouds on the blade from moisture or grease it is a good idea to wipe them away, as the powder will greatly assist in their removal. I did this with my own blades quite recently, and they now look better than they have in months. The powder will also absorb and remove any small amounts of oil left on the blade. I stress that caution is required here, as a small misjudgement in pressure can result in a heartbreaking mess of tiny scratches rather than the clean finish you are after. Repeat with both sides of the blade, and the blade spine.

As stated, genuine swords have a habit of rusting very quickly. In museum displays swords do not appear to rust, but that is because they are frequently coated in archival preservation wax. Although a perfect rust barrier, such wax is highly inappropriate for battle sword use as it impedes easy passage of the blade within the scabbard, an undesirable result for reasons I hope are self-evident. Samurai prevented this by coating their blades in choji oil, which as previously stated is mineral oil mixed with a small amount of clove oil. It should be noted that mineral oil is just as good as choji oil, there is no advantage of one over the other. The prevailing theory for the use of choji oil is that when placed in a ceramic urn as they would have been in ancient times, mineral oil looks extremely similar to cooking oil. Neither carry odour or colour, and both can be used for cooking. The unpleasant surprise comes when we consider that pure mineral oil is sold in pharmacies as a laxative agent; thus the fairly unpleasant scent of cloves was added to the oil to aid easy recognition to prevent certain undesirable after-dinner consequences.

Only a very thin coating of oil is required to protect the sword, but the entire blade must be properly covered. Rust from one spot can creep beneath an inadequate oil coating into the surrounding area. Apply one or two drops of oil to a clean flannel cloth or more tissue paper, and dab along the length of the blade, using more oil where required. Then take the tissue and spread the oil out from those areas to cover the blade in its entirety. Hold the blade up to some light to check for areas you have missed. Remember there should only be a coating of oil, there should be no free-running drops anywhere as they will soak into the scabbard wood and could cause damage. Repeat this procedure for the opposite face of the blade, and the blade spine. It is less necessary to oil the tang, as this may cause blade slippage, but a little around where the handle would meet the blade is a good idea.

As important as cleaning the blade is how you store it. Once you have fully reassembled the blade, choose somewhere as dark and cool as possible. Avoid moist areas such as airing cupboards or non-insulated attic rooms, especially for long-term storage. If you do not use your blade very often, you may wish to invest in shirasaya mountings, also known as storage scabbards. Shirasaya are without guards or adornments, and resemble plain varnished, shaped wood. They are designed to be taken apart for cleaning but not for combat, as they are simply two halves of wood held together by rice glue. If your blade has historic or expensive furnishings then shirasaya will also help preserve these artifacts, by allowing their safe storage elsewhere and cutting down on the wear and tear of regular dismantling.

If these steps are followed regularly your sword, whatever its origins, will last many times longer than it would otherwise. If you are in possession of a signed blade, a sword made by a recognised smith, it is almost essential that you keep the blade in good condition. If your sword is a historic blade from the Shinto or Meiji periods it could be argued that you are somewhat obliged to take good care of the sword. If you own such a blade and are unwilling to give it the care that it requires then I would urge you to auction the blade to a collector who will take the time, so that it may be preserved. It is taking this care that separates a sword owner from a sword collector, and in general the latter is far more highly respected than the former.