Yes electrolysis. I have just done butt load of research on it and is by far more superior method for removing rust , But if you have no electricity then I guess you are sol. The item in image was one piece before this process. Now have $500 dollar antique multi tool.
(Hoo, boy, am I going to hate myself for this --) What do you feed the hamsters that turn the wheel that runs the gennie that runs the sandblast booth? (Or do monkeys throw sand at the work piece ---)
All you need is something to propel the sand. Air, water and apparently steam. Source the energy where ever you can get it. Where I live the old timers used compressed air powered pumps to extract water from deep down over 300ft. Wind Mills were used to compress the air. Even most people who are off grid have access to and use some gasoline, diesel and propane powered engines. Even the Amish use compressed air, most people would consider them pretty much off grid. A pressure washer can also be used to sand blast. I don't recommend using a generator to power an air compressor for sand blasting. Because it takes about a 15hp, 10,000w generator to power a 2.5 to 3hp electric compressor. A single 3hp compressor won't do a lot of sand blasting very fast at all.
@oil pan 4 Ya honda rusted tanks ! , I just did a 500G tidy tank ! Ya didn't get it !! RE FURBISH DUH Stainless 316 & above for 30% nickel !! rest is so-so Sloth
I use most 304 and it works great as long as it stays below around 1000F. Then use 316 filler if I need to weld it together. I tried electro deoxidization about 20 years ago, I noticed the parts rerusted really fast. That is the only disadvantage I know of.
Harbor freight sels a product called Evaporust. I can attest to it's effectiveness . I used in in a rusted gas tank and it came out sparkling ,no scrubbing at all and the product is ecofriendly . Sand blasting will remove material and so will caustic soda . murratic acid will as well . Now for preservation there is an oil that gets in metal but once in it an't be removed it's called Rislone . It smells like Hoppies #9 gun solvant . some of you older guys can remember that one,. Rislone in a engine will save it far better than many other fancy additives. most importantly though it penetrates IN the metal not just on the surface . but remember that it cannot be removed once in side not even hot tanked. A friend of mine tried with an oil pan . he rebuilt the engine and was painting it and the pan kept fish eying oil kept coming through, even after hot tanking ,because the previous owner used Rislone in the oil.
Now, after the clean , change the water soda & the terminals of the power , Use a copper / silver dime , or something to replate the open unprotected metal . Tidy tank for Diesel got a copper pipe that was eaten in pits but plated the inners .. I spent a few hrs over a month for a free tank . Do OUTSIDE in vented area , don't smoke & wear eye protection / body condom !