Today, when cleaning up our swords we can enjoy a variety of products from sandpaper to gentle polishing pastes. But how were soldiers taking care of their swords before the advent of Metal glo, mineral oil or Nevr-dull? I found this interesting excerpt in a French officer memorandum from 1813 which describes some of the options of the time.
Cleaning weapons: To derust portable weapons, we use emery and olive oil, and to scrub them we use soft wood and rough brushes. We clean angles and sinuosities with curettes and spatulas.
If no emery is available, we can also use pulverized sandstone which is sifted and dampened with olive oil to get rid of the biggest stains, and burnt brick, well crushed and also dampened with olive oil for smaller stains.
Every pieces, after having been cleaned, must be wiped with a rag so that no emery, sandstone or brick is left, only a certain oiliness.
Copper pieces must be cleaned with tripoli (rotten stone), or well crushed brick, with vinegar. We must not use fatty substances to scrub them after, as they affect the copper and cause it to oxidize. (another version from 1854 mentions wiping it with vinegar or brandy and rags and to avoid using brushes or curettes)
Saber blades must only be put back in the scabbard once they have been coated with a fatty agent.
We prefer oil to grease for this step; olive oil and tallow molten together (the mix will be even better if, instead of tallow, we use pure wax) in the proportion of 244 gr (half a pound) of oil to 978 gr (2 pounds) of tallow.
Here is a process to purify olive oil. We pour liquefied lead into cold olive oil to a proportion of roughly 245 gr (8 ounces) of lead to 979 gr (2 pounds) of oil. This will evaporate the aqueous substances they may contain, and the crude parts or other foreign bodies will attach to the lead, so that by repeating 2 or 3 times this operation you obtain well purified oil that will aggregate much less than other fatty substances of this nature, and which preserves iron much better.
This process necessitates no other precautions than to put the liquor in a steel pot so that it does not break when lead is poured in, and to let it rest after the operation by exposing it to the sun or an artificial source of heat for some days.
The memorandum also mentions that if rust is well inlaid a polishing stone must be used to remove it. It seems like this method was used all throughout the 19th century.
Source: Mémorial de l’officier d’infanterie. By Étienne-Alexandre Baron Bardin, second edition, Paris, 1813, p. 421.
Another French manual, this one from 1754 has a few variations on the care of the sword.
To brighten the hilt of a sword, you must first scrub it with wet ashes, then with crushed charcoal. You then wipe with a few rags, and to give it a perfect shine you must scrub it with tripoli powder. When the saber has been thoroughly cleaned, you only need to scrub the hilt with Tripoli each time it is used. (This is not unlike how Japanese swords are cleaned after use, using uchiko powder and oil)
To preserve the polish and shine of the blade, and prevent it from rusting, you must once in a while soak a small rag in oil and scrub the blade with it.
To clean the blade and remove oil for inspections, you must take fire ashes on a small rag with which you must scrub the blade well until all the oil is gone. You then wipe it with another white towel. After the inspection you scrub the blade with the oil covered rag.
If you haven’t cleaned the blade in a long time, the old oil might create yellow stains. you must then take no ashes, sandstone or sand, but only new oil and scrub the blade well until the old oil is removed. you then take a little ash and scrub the blade until it comes back to its original luster.
Source: Institutions militaires pour la cavalerie et les dragons. By M. de la Porterie, Paris, 1754, p. 342.
Update: Apparently the wax and olive oil mixture is still being used today for black powder guns and is called “Bore butter”. It can be conveniently bought in ready made tubes, saving you the trouble of brewing oil and molten lead in the sun for days. Be warned that it creates a greasier surface than modern mineral oil. Thanks to Ted Glenn for the find.
HEMA MISFITS (I don't do longsword) 
I believe there is a mistranslation in that latter one from 1754; French uses Charbon for both coal and charcoal and while crushed coal would not make a good polishing compound crushed charcoal does. (Similarly Spanish uses carbon for both, German at least splits it out into Kohle and Holzkohle!)
Hello Thomas,
Thanks for spotting this. It would indeed be charcoal. You are right that there is no equivalence to this word in French, we would rather say “charbon de bois” (wood coal) but of course the distinction wasn’t quite relevant in 1754.