Why use oil?

I don't use either, myself, but I think the "wipes off easily" aspect is part of the appeal of oil over wax. Many use wax for long-term storage of their swords, but day-to-day oil is king, because it's easiest to get off the sword and interferes less with cutting. That is, to my understanding. Someone will correct me shortly.

I've never had an issue with blades rusting, and I consider myself lucky for that because I don't exactly live in an arid environment... However, even the one sword I have in only a tanned leather sheath has never had any rust. Even the sword I hadn't looked at in some three years when I checked it last for something, I don't remember what, was as shiny and clean as the last time I looked at it.

Others have not been so fortunate, and many of them do use wax...but it seems oil is more accessible, cheaper, and easier to deal with.

Yes, that's true, but I think it was the thinner nature of the oil that made it preferable to wax. I want to say I've read before that wax interfered with the edge somehow that was unfavorable in cutting, but again, it's been a long time since anybody's discussed it. There's no denying a slippery blade goes through things more easily. I think the reason oil is preferred to wax is because it shows its own marring less and generally lends itself to a more even coat that doesn't interfere overly much with the scabbard's own methods of water dispersal.

Again, I don't use either, so I'll let someone else who does chime in. I'm just throwing out what I've heard from others, because nobody else is taking.

I'll bite. I generally don't store with a coating. I use (about once a month) Eagle One wading polish from the auto store. It wipes on like an oil, I wait for it to dry to a haze, then polish off with a clean cloth. Nice luster. They're a soaked wading cloth ready to go and can be used many times. Even if I don't wait for it to dry to a haze, the initial application cleans it up nicely.

I have coated a few blades I was storing for 3 years, when I came back to them, the haze was still coating the blades and they were no worse for wear.

Me too.

Some oils and waxes are lubricants, and some a sticky. (Consider surfboard wax.) Don't want one that's too sticky, but this isn't a big deal for swords.

Wax: more permanent
Oil: easier to apply, re-apply, remove

Want to polish a sword? Sharpen a sword? Want wax on your stones? Better remove it first. Easier to remove oil.

Cut with it? Will you need to clean gunk off the blade afterwards? That's easier if oiled. Either way, need to re-oil or re-wax afterwards.

So oil is more convenient for swords you cut with often. But wax has its advantages, as you pointed out in your OP. Wax is better for display only swords, swords you take along places for kids (and adults) to handle, and more. As others wrote above, silicone sprays/wipes can be great choices, too.

A lot of katana owners like oil for the ritual aspect. Even if a silicone spray is better, they'll use oil, for tradition.

Ordinary oil doesn't displace water, at least not in the way that the term "water displacement" is used for oil products. WD-40 for example, was designed specifically to displace water ("WD" stands for water displacement). Regular oil does nothing to break water up into smaller droplets (emulsify), so the surface tension of the larger droplets of water can hold it to the surface of the steel even when covered with straight oil. Water-displacing oils such as WD-40 have added ingredients such as alcohols to break up the water and lift it from the surface of the metal.

Salts aren't necessarily taken care of with oil either; generally, ordinary water is the best cleaning solution for salts. This is how guns fired with corrosive primers (corrosive due to salts) have to be cleaned. If you don't first clean them with water, but rather use ordinary cleaning solvents and oil, the steel will corrode. The typical cleaning method is to use water to dissolve and rinse away the salts, then WD-40 to displace the water, then cleaning solvents, and then coat with a light film of oil.

In any event, it is best to properly clean and dry the surface of steel before protecting it with oil or wax. Fortunately, this is easy to do with a sword blade. For things such as wet guns or carburetors, it isn't so easy just to wipe the water off of them, which is where products like WD-40 come in handy.

I would imagine wax would be more difficult to completely remove from a blade, at least more time consuming than removing choji oil. After cutting with my sword I spray it down with Windex, wipe it clean, hit it again with 90% isopropyl alcohol, dry the blade and then use a soft cloth I've kept in a plastic container and semi-saturated with clean oil, to put a thin coat back on the blade. Quick, cheap, easy, and I've never had rust issues.
I'd likely use renwax if I was storing it long term.

-Josh

Neither one of them did too well in this test:



3 weeks outside with occasional rain, and they both rusted enough to cause significant pitting. I would be very surprised if that brake rotor would have rusted at all under those exact conditions (which weren't particularly harsh) with a good coat of wax, or even grease, on there. As an example of the effectiveness of grease: a few years ago I replaced the entire brake system in my '69 Dodge Charger (it is a beater, but solid), which included a new master cylinder, which was raw cast iron. It was completely coated with rust within a week or two. That didn't harm anything from a functional perspective, but it was ugly. Last summer I converted to front disc brakes (it originally came with drum brakes, which are scary in the front), and this required a different style of master cylinder, so I bought another new one, also raw cast iron. This time I dipped my finger in grease and rubbed it all over the surface of the cast iron. Last I checked, it was still 100% rust-free (which would have been a couple of months after I coated it with grease; I can't easily check it right now because it is under a few feet of snow). I also make a habit of coating threaded fasteners with grease, and ground points, and I haven't had any of those rust on me either.

However, in most rust/corrosion tests, they do salt spray tests, which is a much harsher environment than simply being outside in humidity and occasional rain. Salt is an abrasive (and also a catalyst for corrosion), and combined with water pressure, can quickly remove coatings such as wax, oil, or grease, leaving the metal unprotected. At that point, it is obviously going to corrode very quickly. A product like WD40 Specialist Corrosion Inhibitor or Frog Lube, which is applied to heated metal, and gets into the pores, would stay on there longer under such conditions. But in conditions that aren't harsh enough to quickly remove wax, grease, or oil, I suspect that they would fare better. In other words, it seems to me that wax, grease, or oil offer more complete protection, but they are more easily removed from the equation, while products like WD40 Specialist Corrosion Inhibitor or Frog Lube offer less complete protection, but stick around longer under harsh conditions, due to getting into the pores of the metal.

Preventing rust is very simple. The formation of rust requires 2 components: oxygen and water. If you can create a barrier to either one of those components, rust can not happen. Wax and oil (and grease, which is just oil emulsified in a soap base) are both water and oxygen impermeable.

I would like to read the 48 brands test though; do you have a link?

That's ideal for a sword in my opinion.

As for silicone spray, I don't know how well it would do over time with regard to rust prevention, or how easily it is wiped off. I use it for two things: lubricating the steel pivot ball on a 1980s Nintendo arcade machine joystick (it works great for this because it is so light; oil and especially grease make the stick sluggish when returning to center), and for lubricating the wipe strip on car windows, which makes them easier to roll up and down (it doesn't harm rubber like petroleum-based lubricants can). Unfortunately, the good stuff (3M 08897) is expensive; a dollar an ounce or so.