What should you have in your cleaning kit for your typical production katana?
It’s very simple and you don’t need a store bought kit or even any fancy and expensive gear.
What I’m recommending here is not for Nihonto or blades with a high level and expensive polish. If you have a blade that isn’t nihonto or expensive but let’s say has a high mirror polish and it’s for display and you will never cut with it, you should change one of the listed items. For any production blade you will be using to cut with, that will eventually build up surface scratches, the following is fine.
I use simple paper towel to clean and wipe down my blades. these won’t do any damage to typical polishes though will probably build up micro scratches over time. If you prefer a softer material, use a clean cotton cloth or microfiber/micro flannel.
Isopropyl/rubbing alcohol will remove most debris, grease and oil. Use the highest percentage you can as this will contain less water and will evaporate more quickly. If there is very stubborn debris, such as maybe gunk from mats or bamboo, you can use a simple glass cleaner such as Windex. Don’t use anything too harsh or that contains heavy duty chemicals. Sometimes the blade will not get very dirty at all and simply wiping it down with blade oil can do the job.
You should have something in your kit to aid in removing the mekugi when they’re tight, such as a mekugi-nuki. These come in many forms, including the most popular, little brass “hammer”. They’re typically in two parts, a thin punch and the hammer. Be careful as some of these types have sharp edges that can damage mekugi, especially the cheaper and softer “chopstick” variety.
I make my own, as seen in the pic. There are many other everyday household items that can work as well, avoid using anything sharp or that can damage the mekugi or tsuka.
Sometimes the tsuka will be fairly or very difficult to remove by hand so I like to keep a small wood block in my kit to aid in removal. I simply took a small rectangle of scrap wood and glued a piece of leather on one end and one side. I place this on top of the blade side seppa, with the leather against the seppa and also against the habaki. Hold it tight up against both and give it a few taps with a mallet. Alternate sides. Don’t ever use a metal head hammer and of course remove the mekugi first. For a video tutorial on removing a tight tsuka follow link
I keep a rawhide and rubber mallet in my kit. I use the smaller rawhide mallet to remove the tsuka and the heavier rubber one to put it back on, protecting the kashira.
I use paper towels or cotton cloth to clean the blade, as mentioned but to apply fresh oil, I like to keep a clean piece of cloth, lightly saturated with clean oil. This helps avoid applying too much oil or making a mess. I keep this cloth in a small plastic container to keep it clean and fresh. When the cloth becomes dirty, I replace it. When the cloth becomes dry, I add more oil.
As for oil, any good quality thin oil used for rust prevention and general blade/tool maintenance should be fine. Which type or brand is personal preference, some like more advanced formulas, some prefer extremely simple. Thin or light mineral oil from the drugstore, typically used for skin, is fine.
I also like Camellia oil. Most of the time, I use a simple sewing machine oil. Many of the “Choji” oils sold as sword oil can be on the sticky or goopy side and often contain cheap oil or are not mixed in proper ratios with clove oil. If it’s super cheap, it’s likely not the best thing to use. The real trick to oiling is to go simple and light. All you need for a clean blade is a super thin layer, avoid any amount that pools or drips off the blade since this will only wind up damaging the saya and will collect more dirt and debris, which will in turn collect moisture that will damage your blade.
So, that’s pretty much all you need for a typical production cutter. It’s recommended to not wipe your blade down before cutting targets since the layer of oil already on it can help prevent the blade from collecting debris and will help repel water, if cutting water filled jugs or bottles. One thing to keep in mind if cutting wet targets is to try to avoid letting the liquid run down inside and under the habaki. It’s good practice to keep cloth on you when cutting so you can quickly wipe the blade before re-sheathing or letting the water travel too far down the blade.
One other item I keep in my kit is not for cleaning but for saya maintenance. The more you un-sheath and re-sheath your blade, the more wear you’re causing on the wood inside the saya opening, called the koiguchi. This will eventually wear down enough to loosen the fit of your habaki. This is normal. Also, if you live in a climate that changes drastically, you might experience a fit that can be tighter and looser, even without much use. Having some thin, non acidic wood veneer is helpful for adjusting the fit. If your habaki seems loose inside the koiguchi, add a small piece of veneer to the bottom of the opening with some craft or wood glue. Don’t use harsh glues such as super glue or expanding glues. This should tighten the fit. If too tight, simply use a small file to remove some wood from the same area. NEVER USE SANDPAPER. Don’t apply shimming to the side walls since this can cause the saya to split at the seams, which are located along the ha and mune. If your koiguchi fit is already very tight at the sides, usually noticeable by scratches on the habaki, you can file them down a bit. Wood veneer good for this purpose can be found with the name kyogi.
I hope some or all of this information is helpful 😊
With regular use, these 2 ounce bottles should last a good long time. Results may vary depending on your individual climates and application technique but I have seen little to no reduction of the coatings I applied on my blades over three months ago, and it has been fairly humid in my area. Of course, always check your blades that are not in use periodically and clean and replace the oil as necessary. It might be common knowledge among long-time sword collectors and sword arts practitioners, but for those who don’t know how to clean and re-oil your blades, I will be posting an easy to follow guide that will be available on the oil sale page. 
