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 Post subject: rust paint
PostPosted: Sun May 10, 1998 4:47 pm 

does anyone have experience with the paint which you can put over rust to seal it in, then paint over it?<br>

 Post subject: Re: rust paint
PostPosted: Mon May 11, 1998 2:31 am 

Why would you want to just cover rust. This is only a cosmetic fix. There is no way to fix rust except to get rid of it. Blasting with a beneficial media is one way. Grinding, sanding or chemically attacking it are the other methods.<br>

 Post subject: Re: rust paint
PostPosted: Mon May 18, 1998 5:38 am 

<br>You are right on the world of RR preservation, though rust can be reduced to a pure metal state through very careful electrolytic reduction. Problems - you have to separate EACH INDIVIDUAL PIECE. All fasteners will most likely be destroyed, and they are a great deal of the object's inherent worth. Each individual piece ideally goes into it's own vat, and is reduced, and yes, I can reduce rust to iron. Simple. Get rid of the oxygen and the chloride/sulphate ions. However, if the structural matrix is destroyed from corrosion expansion (rust jacking), well, that's all she wrote. Lots of pristine pieces of shapeless iron. <br>Now, how does one apply this to a heavywieght bag car? You tell me. <p>BTW, all the blasting in the world will not cure somthing that is contaminated. <p>Bob mentioned something to me that got me thinking.... iron/steel corrodes based on a curve between the ambient Ph and the electolytic (galvanic) potential. Even Cor-10 steel will rust away at the wrong Ph, given small galvanic charges. However, inducing a current on the piece knocks it out of the curve, problem being, everything has to be electrically well connected by liquid or mechanical means. Like Bob said, the navy does this on ships, but they are sitting in a very conductive bath of salt water. <br>One other important point, you think you've gotten rid of all the dissimilar metals? Steel itelf is formed of dissimilar metals, at least four depending on the steel. Magnetite, cementite, hematite, graphite, plus the admixtues of chrome or whatever. etc. All it has to be is wet and you've got a battery, and hence, corrosion. Add contaminants and you have iron sulphates, iron sulphides, and iron chlorides and chlorates at even higher galvanic potentials. <br>Fixorust, chemically attacking the stuff is the way I see on heavy equipment. Phosphorus has a greater affinty for iron than oxygen. Turn those iron oxides into iron phosphates, it's one of the most stable of the iron compounds. Get rid of the water next. get the thing under a shed if you care anything about it. Move it to Arizona. Whatever. <br>I've been having really good results with magnesium chlorate for getting rid of sulphate contamination, won't work with chlorides though, BTW. <br>Coating it with paint is a halfway solution, iron will expand many times it's original size when corroding, so it will blow the paint off given less than half a chance, the water gets back in, and away we go. The force of this is something you have to see to believe. I have seen a 3/8" x 16" x 16" plate lift about 30 tons of masonry several inches. You will have localized really nasty corrosion cells as opposed to overall rusting. These cells will eat the important parts of your artifact (where it's joined together) fairly quickly. You will have lots of stuff to make pencils (graphite) and no artifact. <br>Anyrate, the next person who talks about raising the Hunley to save it, please report to Savannah, Georgia to finish the lobotomy that was obviously started and not completed. <br>

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