i know I'm bringing back a old post... but i just finished reading every single post on this forum Friday and i gave this method a try over the weekend. i used a 5 gallon bucket and the little old 6 volt charger i use on my truck, i was very impressed with just 7 hours.
but i got a couple questions about different details to this. i noticed that the water became more "active" when i turned up the charger to 12 volts, does the higher voltage increase the speed of the process? i noticed above that someone used a welder! I'm not in that much of a hurry but did that in fact speed it up a lot??
also, if i needed to get a lot of small parts cleaned, could a person hook a good clean metal "plate" to the negative, lay it on the bottom of the tank, and lay the parts to be cleaned on it? assuming if this were to work, a small spot would have to be cleaned where the parts sat on the plate. just brainstorming
i told my step dad about this cleaning method.. all he had to say is that he didn't thing i could find a tank big enough to fit my whole truck! HAHAHA!!
RE: voltage and speed:
I chaperoned my kids field trip to UC Berkeley, where they were de-rusting ancient metal artifacts using the reverse polarity technique.
They emphasized keeping the voltage low (I remember 5 volts DC) and taking a long time to lessen loss of metal to the emulsion.
Also, no physical contact between the item and the tank or the electrode.
Always connect your object to the negative.
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I've used this method in getting rust off metal. I've also burned out several small battery chargers. The one I use now is a larger one. The smaller ones just stop working. I set my charger on 6 volts 4 amps. does great. What I do is put my metal in the soda treatment for about half an hour, soak it over night in white vinegar rinse and put it back in the soda treatment for an hour 6 v-4 amp. The metal seams to come cleaner this way. I made several different shape holders to soak parts in vinegar. Hood hinges are one that needs to soak in vinegar to free them up. after getting them freed up it should be taken apart and cleaned an lubed. What I used to soak the hood hinge in is, I took a piece of 2" pvc pipe cut it 6"longer than hood. cut a 1 1/2" split the length of the pipe, caped both ends,filled with vinegar let set over night, check movement in hinge and soak again. the hinge should move more freely, if not free soak again and again!!!!! you can soda bath this also
I don't think its the voltage as much as the amperage for how quickly this set up works.
Some guys have baskets formed up from metal mesh, or use an old frying basket and just drop all the small parts into the basket. Hook up the basket and your ready to go. give it a few shakes after a few hours or flip the parts and supposedly you get complete derusting coverage. I haven't been able to get this method to work that well for me though.
Maybe you can't find a big enough tank for you body but there is always a way. I swear I saw a picture of some guys using this method on the body for a hot rod, in a swimming pool, and using multiple dc welders. I think they also made a cage with rebar that was there cathod. Not saying this is safe by any means, just that it can be done if you are willing.
Another option to consider (especially on AA cabs) is building a frame with 2 x 4s and laying plastic sheeting to make a "pool" large enough to fit half of the body in. You could probably use the bed of a pickup truck while propperly supporting the chassis on jack stands or if you have a large dump/express bed, lay in your plastic and fill her up. You run the setup for a while, then rotate and repeat until the entire body is derusted. When using this method you need to make sure you have sacrificial metal inside the cab WITHOUT touching the cab (rebar hung in an upsidedown tree like fashion works pretty well but doesn't have the surface area that plate does). You also need to lay down some wood blocks so your body doesn't scratch through the plastic. On the other hand if you do have an old pickup bed that needs some derusting and it holds water, you could just hook up the bed as the negative side and drop in your body without the plastic sheeting.
I don't really understand why everyone says that the sacrificial metal and the peice being cleaned can't touch the sides of the container. If you have a plastic container then it doesn't matter unless so much metal comes off your parts that the bottom of the container has a layer of metal that allows the current to flow through. Usually by the time this happens I've changed out my water because mesquitoes larvae and dirt make the water disgusting.
Of Note: I am considering the 2 x 4s and plastic sheeting on my body just because this process make it soooooo much easier to sandblast. I don't know if I would consider painting over all the residue thats left behind, and scrubbing a full body with 3m pads would take way longer than just buying 100 lb pressure pot from HF. So hydrolysis then sand blasting is the plan for me. If you haven't tried it I sugeest you do it on a few test materials. The hydrolysis breaks up all the real difficult rust, and the black stuff lefts behind is rediculously easy to sandblast off.
i did a little test and i noticed that about the black after wards, incredibly easy to clean off. i got a 55 gallon drum now and my next victim is going to be one of the windshield frames.
at first i didn't like the vinegar idea to much due to the difficulty of neutralizing it all but i suppose that the soda and the bubbling of the solution might do a pretty good job of easing my mind
i've used white vinegar and muratic acid to de-rust parts (not together, though!).
the vinegar was more of a soft cleaner that took time to get the job done. i put a few gallons in an old kitty litter bucket and covered it when i wasn't actively digging through it or scrubbing the parts. i don't know if it made a difference, but my theory was that with the solution contained, it would concentrate and work better than it being exposed to air and dissipating. vinegar does remove paint, but unless it's loose, it takes awhile. it's also soft on the skin.
the muratic acid is a harsh, quick cleaner/de-ruster. two gallons for $10 at home depot. must be used outside, and i'd personally recommend wearing a mask (at the very least, hold your breath) because the vapors are pretty intense. i also used an old kitty litter bucket for this, covered it when it was cleaning parts (maybe 5 mins) or not in use, kept it outside. it'll eat away thin parts like speedometer numbers, as i found out, but if you have heavy rust and want a quick shock to get most of it off, this is a good method. don't let the acid touch your skin... wear gloves, use wire hooks or baskets. my plastic cooking strainer worked good at first, but after the coating melted off, it didn't last long. my old metal fry basket got tarnished quickly. if you feel you must dilute it with water, remember it's acid into water, not water into acid!!!
i've also put purple cleaner (some use simple green) in an old crock pot no longer designated for food.
i also found the small brass bristle brushes with the wooden handles work very well for cleaning small parts, and opening the surface for the chemicals to do their work better; the vinegar especially. since the vinegar does work slow, every other day i'd brush the parts soaking in it with the brush. kept that up as long as it took until i was satisfied with how clean the part was. i used quite a few of those brushes, and unfortunately i can't find the 3-packs for $1 anymore.
with any of these cleaners, it's important to wash the parts completely and thoroughly when you're done. especially with the muratic acid, since you don't wanna touch that! since my acid was outside, i just ran the parts over to the hose. the vinegar and purple cleaner, i just ran under the sink; sometimes with the brass brush and/or an old toothbrush. sometimes you gotta wash them under water before you try to de-rust further. most importantly, in order to prevent flash-rusting, you've gotta spray the bare metal with pb blaster or wd40... something like that. i let the parts sit another day or two after spraying with pb blaster before wiping them down to work with them.
oh, and as with anything like this, the solvent does break down after awhile and loses its effectiveness, so you have to dispose of it correctly and replace it.
