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Removal of Surface Rust


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Hi Everyone,

Apologies if this has been discussed prior. Looking for advice/techniques on treating and the removal of minor surface rust from interior pieces. I recently moved to a wetter climate and now have notice some parts I had stored have surface rust on them now. They range from metal dash parts to engine parts.

What do all of you folks use to remove and then treat so it doesn't return?

Appricate any advice on what products to use and opinions.

Thanks

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I am a big fan of Evapo Rust. It is a non toxic water based rust remover. It will work good on the light surface rust you describe. The parts must be soaked in a container of Evapo Rust. It has an ingredient to prevent flash rust for a while after treatment. It is best to paint the parts while clean. It is not supposed to remove good paint or plating. My experience is that it will take off paint but not plating. Engine parts that are not to be painted can be sprayed with PB Blaster. I don't think that evaporates like WD-40. 

I live in the midwest.  I had the same problem with parts rusting in storage and the top of my table saw had light rust on it. I went all out to solve the problem. I insulated and finished the walls in my workshop. I got doors and windows that seal better. I got a window air conditioner and a dehumidifier. The portable dehumidifier was the single most effective means to solve the humidity/ rusting problem.

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At about $20 - $22 a gallon, Evapo Rust is a little expensive. It will not eat into unrusted steel if you need to soak it for a long time unlike phosphoric acid. I looked at the msds on the website and it did not say it was phosphoric acid. How do you know that? I don't know. I always assumed it was not. 

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Evaporust is *NOT* phosphoric acid. I see this come up again and again in the forum. I have probably seen and used every new "miracle" phosphoric acid rust remover to come down the pike in the last 40 or more years, and their characteristics are all similar. Evaporust is *NOT* the same. There are some pretty glaring differences.

 

All of these phosphoric acid cures will eventually stop eating rust and form a hard black skin over the top. They advertise this as "rust conversion" but if you break through it, there is still rust under there. Removing rust always involves multiple cleanings with a wire brush or whatever and will never quite get to the bottom of all the pits thanks to this skinning behavior.

 

Unlike phosphoric acid, Evaporust is not really suitable for parts that cannot be immersed. You can try to soak paper towels with it and wrap in plastic, or even arrange a drip. It is extremely slow, fiddly and does not work very well. They may even have a product for this type of use, but I would be skeptical.

 

If you can immerse the part in Evaporust, the rust turns to a black powder and falls into the bottom of the vat. It WILL get all the way to the bottom of the pits. It will get there a lot faster if you take the part out now and then rinse any of that loose black powder off that may be slowing things down. Either way, the reaction will continue until all the rust is gone. It works faster when warmer, and if it gets too cool the reaction temporarily stops. You want this stuff in a warm room. If you leave the part in "too long", or intentionally leave it in a long time to insure you got all the way to the bottom of every pit, the part will turn black. This is harmless, and does not resemble the crust from phosphoric acid. Most will wash off, but what remains will resemble discoloration from heat or gun bluing.

 

The black powder falling off of a part in Evaporust most closely resembles what happens in an electrolytic derusting vat. Electrolytic derusting is much cheaper, and therefore doable on a larger scale. The downside is that there is somewhat of a "line of sight" problem, and areas that are farther away from the electrodes may not get completely done. For instance, the internal ares of a rusty door or trunk latch mechanism might not ever get completely done. Evaporust has no such limitation but is expensive, so better for smaller projects.

 

FInally, phosphoric acid burns your hands, while Evaporust is watery and sticky. Phosphoric acid fumes are acid fumes, while Evaporust fumes are not very strong and are sickly sweet.

 

If Evaporust is related to any old time method, then it must be related to molasses. It resembles sugar more than anything else. It turns to a nasty sticky goo if it dries, but washes off because it is soluble in water. When my vat leaked a little the ants went crazy for it at first, and then decided they didn't like it.

 

 

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And it works... lousy, but it still comes without all the disadvantages of phosphoric acid. I have done this and will probably do it again, but plan for it to take a long time, lose a lot of liquid, and need constant babysitting. It also ruins some pumps. The magic comes when you can submerge the parts. If you can do that, nothing else really comes close.

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