So Evaporust is citric acid pre mixed in water. So you’re paying for a pre mix.
People old and with long memories will remember the original Navel Jelly(not the eco-friendly stuff they sell today by the same name). It was the same as Evaporust in results and often left your metal darker.
Uhhh... No.
I am not knocking either of those things as rust remover but they are both acid, and Evaporust is not acid. It is PH neutral. Acid is going to attack the base metal on some level or another because it is acid. Extra care is needed.
Naval jelly and most rust removers from days gone by (and today for that matter) are based on Phosphoric Acid. This includes Naval Jelly, Ospho, Jasco, Coca Cola (LOL), and a million others. My experience with these, which are often called "rust converters", is that they never get all the rust. They get some of it and then skin over whatever is left with a black phosphate. While this can slow down rust a lot, it just ain't what I am after if I am trying to REMOVE ALL of the rust. Evaporust will get all of it, given long enough to work. Once you are down so the only rust is in deep pits, the surface area of the pits is tiny and it takes forever, but it does not stop. Phosphoric acid will skin over with black phosphate and stop.
Vinegar is Ascetic Acid. It removes rust. Being an acid, it also attacks base metal. It can work well. You probably want the canning grade. It is stronger.
Citric acid probably works too. It is also in the canning aisle, and it is also acid. I don't have much experience with this one. I have a bunch of the powder I bought trying to go after lime deposits. I hear it removes rust too. Your mileage may vary.
Muratic Acid (pool acid) is aggressive as hell and removes all the rust. It also attacks the good metal pretty aggressively, though slower than it attacks the rust. Read up on this one and how to handle it so you don't have any explosions. Protect your eyes and everything else. DON'T breathe the fumes. It ruins almost anything it touches. Don't keep it in your house or shop. It can be sitting in a sealed jug, and other iron and steel stuff in the same building will start rusting faster within a large radius. I can't explain that. It can be extremely useful in some situations. Your mileage may vary.
Oxalic acid is a terrific rust remover. It is an acid, so no doubt also attacks the base metal. Like all acids, it needs a close watch on progress. The best results I have ever seen on bicycles with the least apparent paint loss I have ever seen have been in CABE threads by other people. I have only used it on small parts. I like it.
So much for acids. If you want to go down a DEEP Internet rabbit hole, there are people who think they have identified the chemical in Evaporust, using spectroscopy and reading old scientific papers and so on. It is nothing you could just go out and buy in the canning aisle, I'm sure of that. If identified correctly, it is also nothing you have ever heard of unless you are a chemist. Is it overpriced? Maybe. Probably. Are there cheaper products that might have the same chemical? Probably. Are there more concentrated versions available somehow so you aren't shipping a bunch of water? Probably. I don't know. As I said, the rabbit hole is deep. I invite you all to go look. I gave up.
Evaporust in no way resembles any of those previous acid-based rust cures. I can only assume the people saying so have never actually seen any, or got any on their hands. The only old fashioned rust cure that seems similar is molasses. I understand that it works well, and is probably a lot cheaper down at the farm store. Of course molasses stinks (not that Evaporust is entirely stink-free), and molasses is going to attract bugs because it is sugar. There is a persistent ant problem in my neighborhood, and the ants went for my garbage can of Evaporust for about a day and a half. Then, they decided they did not like it at all. They never came back. Molasses also might be acid on some level, but mainly works by chelating rust just like Evaporust does. It is the closest thing you are going to get for cheap in bulk, but may be impractical for some of us to use.
There is also electrolytic derusting. The results are errily similar to Evaporust, and it is way cheaper. The trouble is it sort of works well as line of sight from the steel electrodes, so it doesn't work too well on hollow parts or mechanisms that don't come apart. Evaporust does not have that limitation. Electrolytic derusting would work awesome on something like a fender where the surface is all on the outside. Read lots of HOW-TOs so you don't get the polarity of the power supply backwards due to someone's typo. That will damage your parts. It is pretty harmless when done right, just like Evaporust. In my opinion it is going to remove paint, but in my experience so would Evaporust. Either of these methods will get to the rust even if it is under paint, and then there is nothing holding the paint on anymore.
