WhO's THE BEST, rust remover/ encapsulator Options

[mrgjones]

Alright. There are a lot of products on the market that promise to remove rust and prevent it from coming back. From reading the threads it seems the opinions on this forum are as varied as the products themselves. This thread is about making a convincing argument... or a ludicrous allegation, which ever you find appropriate. Horror stories are welcome but please limit yourselves to the chemical rust abatement theme already established. For you slow starters, here is your motivation.

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[Katmanken]

I think the electrolytic process is the way to go. There is a place in Cincinnati on Northland Blvd near the Porsche dealership called American Metal Refinishing that seems to use it and can do a whole car in their tank. I use it at home for everything with no problems. Per the line of sight, yes, but a little creativity never hurt. Can you say coathanger electrode inside a tube? American Metal refinishing can get inside of the cavities if you request it. They removed the paint, inner foam, and all of the the rust from my trunk for $60-$70. The worst that I had to do was slap the rear lip area of the trunk to knock the chunks of blackened and killed rust out of the latch hole. Not sure what process they used as the blackened rust bubbles aren't created with the electrolytic process, but it worked.

Per the hydrogen embrittlement concerns, do your metallurgy. I think you will find that hydrogen embrittlement affects really HSLA ( high strength low alloy) steels or hardened steels, and doesn't do much of anything with non-heat treated steels like the mild steels. For those of you that don't know, mild steels were the automobile steel of choice due to the ductility, low cost and ease of formability before the late 70s. The Japanese pioneered the use of HSLA steels in the mid to late 70's which made the body panels both harder and thinner due to heat treating. HSLA steels are succeptable to hydrogen embrittlement and reduced strength from heating which is why they don't recommend welding late model cars. HSLA steels are also highly prone to rust as witnessed by the notoriety of 70's and 80's Hondas as rustbuckets with shock towers shooting through the hoods, gaping holes under the bumpers, and windshield pillars rusting through for your rollover pleasure. No, I wouldn't throw a nitrided crank in the tank, and ball bearings may fall off the electrolytic list, but I have seen pristine cast iron engine blocks as they come out of the tank.

Yes, it was my amazing rusting-before-your-eyes POS Honda that made this engineer research the mild steel vs HSLA topic.

[Madswede]

Per the hydrogen embrittlement concerns, do your metallurgy. I think you will find that hydrogen embrittlement affects really HSLA ( high strength low alloy) steels or hardened steels, and doesn't do much of anything with non-heat treated steels like the mild steels. For those of you that don't know, mild steels were the automobile steel of choice due to the ductility, low cost and ease of formability before the late 70s. The Japanese pioneered the use of HSLA steels in the mid to late 70's which made the body panels both harder and thinner due to heat treating. HSLA steels are succeptable to hydrogen embrittlement and reduced strength from heating which is why they don't recommend welding late model cars. HSLA steels are also highly prone to rust as witnessed by the notoriety of 70's and 80's Hondas as rustbuckets with shock towers shooting through the hoods, gaping holes under the bumpers, and windshield pillars rusting through for your rollover pleasure. No, I wouldn't throw a nitrided crank in the tank, and ball bearings may fall off the electrolytic list, but I have seen pristine cast iron engine blocks as they come out of the tank.

(IMG:style_emoticons/default/agree.gif) You took the words right out of my mouth! (IMG:style_emoticons/default/beerchug.gif) I would emphasize that the most common cause of hydrogen embrittlement in steel is where there is high pressure and relatively high temperatures during the manufacturing process, both of which will not exist in an electrolytic solution. A high concentration gradient could drive H2 to diffuse into steel as well, but the reduction reaction isn't fast enough (and hydrogen is the lightest gas there is) that it won't be in very high concentration in the solution such that there would be that concentration gradient as a driving force for significant diffusion.

Also, the "line of sight" thing is true in a way. For whatever reason this occurs (I suspect its more of a rate of reaction due to the electrical field between the anode and cathode as opposed to not working at all), from my own research it seems a large enough tank and spacing between the anode and cathode solves this problem to a large extent.

Anyway, I still think electrolysis would be a promising method for that special case where the car/parts in question have lotsa rust all over but not enough to ruin the structural integrity of the part (in other words cut it out and replace it).