I will tell you everything I know about rust removal. FORGET WD 40 AND LOTS OF WORK. THIS WILL THIN OUT YOUR BLADE AND RUIN THE LINES OF YOUR CUTLERY. I have tried so much products and techniques for removing rust and pits from cutlery in the past. I have lots of experience in this. I hope this will save you from all the headaches I have had before while dealing with rust. I only suggest these:
Red Metal Finishing Pad~ This works well as an abrasive to remove surface rust from blades. Note that I said surface rust, as it will NOT get the black hardened oxides from within "pitted" metal. Pitting is spot where the red rust (which is the worst kind, red rust is active and will eat away at un-oxidized metal) has eaten a tiny hole into the surface and left behind more stable black rust. This black rust acts as more of a patina, and is more stable than red rust. I still hate it.
1000 grit Wet/Dry Sandpaper~ (black) This is good for creating a mirror finish on metal. This only looks good if there is no pitting just FYI. Use honing oil or some type of lubrication while you lightly sand if necessary. This also works for getting rid of the micro scratches left over on your blade after using a Metal Finishing Pad, Or Green Kitchen Brillo Pad.
CLR (Calium, Lime, Rust)~ A household cleaner. You can purchase this at a local hardware store for six dollars. It is a green liquid that has an acid in it. Acid is a harsh word, keep in mind. The product will melt the oxidation right off steel. For use let the metal soak FULLY SUBMERGED in the CLR for ten-fifteen minutes AT MOST, Then use a Metal Golf Club Brush, or Brass Brush/Metal Finish Pad/Steel Wool as an abrasive on the metal. The Oxides should come right off after about five strokes from whatever metal you are using. Keep in mind**** You need to thoroughly clean the metal you used the acidic medium on after an application, or it will create rust again. All the CLR will do is melt that oxide and make it loose, if you apply the CLR without abrasive cleaning and cleaning afterwards, the metal will pit and become more rusted. I know this from personal experience. You also will need a container to contain the CLR and whatever you are removing the rust from while it soaks, as it cannot be applied with a cloth without hurting your blade; such as a mason jar, pickle jar ect. You should only use CLR on small things such as pocket knives, multitools, ect.
***FOR LARGER APPLICATIONS SUCH AS SWORDS: Use naval jelly instead of CLR. It is more powerful than CLR, Less harmful in my opinion, and is a gel based product as opposed to CLR, which is liquid. You don't need a container, just apply directly to the metal with a cloth or Q-tip. Apply Liberally, use abrasives such as the ones listed above, then rinse with warm water. Please take my advice and have at least a pint of K1 Kerosene to wipe your metal down with after the cleaning with water. K1 Kerosene is a petroleum distillate based penetrant that will remove all the remnants of the CLR/Naval Jelly and protect your blade. I suggest Naval Jelly over CLR for all applications, but CLR is second best. Loctite makes the Naval Jelly I use, found at any hardware store for $6-7.
Rem Oil~ Works well for cleaning of debris from metal and rust prevention. It is petroleum distillate based, so do not use directly on leather, as it will darken and dry the leather out. This is a 2 in 1 product. I use it more for cleaning than oil. It is okay to apply to a metal, then sheath in leather. Rem Oil is a gun oil found most everywhere.
Hoppes Weathergaurd Oil~ Works as a rust preventative and lubricating oil. This is what I used AFTER I use Rem Oil. It doesn't collect lint like Rem Oil does..
A Brass Wire Brush ~(Found at a Gun Specialty Store for $1-3) Use as an abrasive on metal. The ONLY thing that, together with Naval Jelly will fully remove oxidized rust from the Pits in metal caused by rust.
Steel Wool ~ A fine abrasive made from steel. Found at most tool stores. Steel Wool will leave behind metal powder on metal that will only come off with oil. (Use Rem Oil)
Green Brillo Pad~ Basically a wimpy version of the Metal Finishing Pad. It is finer, and will leave green powder behind. I follow up a metal finishing pad with a green kitchen pad for finish.(FYI)
My best advice to you is buy Loctite Naval Jelly, A Metal Finishing Pad, A Brass Wire Brush, and Can of Rem Oil.
Start by liberally applying Pink Naval Jelly to the entire machete blade with a rag. Rub the blade down with the metal finishing pad liberally, then rinse thoroughly with warm soapy water, dry with paper towel, repeat until rust is removed. This may take a few applications.
If the metal is pitted and you want to remove the oxidation from the pits, brush the pitted areas with a brass wire brush. This might take a while. Finish with rem oil.
If you have any more questions feel free to ask. I don't want anyone to have the headaches I had with this. I know a good deal about rust removal. Take it easy. -Zemapeli