wallaby Posted April 13, 2006 Share Posted April 13, 2006 I have some pieces of potmetal that are in near perfect shape but they have some areas where corosion is becoming an issue. The damaged places might be pinholes or missing plating, but they form a lump of corosion that grows up & out of the area and rubbing away the lump isn't really a solution. I'm wondering if anyone knows of a chemical or process that will stop the corosion so I can maybe paint over the area and be done with it. I know POR15 works to do that with iron oxide (rust), but any ideas what to use on potmetal? Link to comment Share on other sites More sharing options...
alex's72fgmc Posted April 13, 2006 Share Posted April 13, 2006 pot metal is almost poured alluminum so one thing i would try is called "alodine" it is a corrosive yellow liquid that you emerse your part it for 30 seconds to a minute to corrode it and prevent oxidization. then rinse it off with water. "the idea behind it is you can only have metal corroded by one form of corrosion not by multiple forms. basically once its corroded this way it wont corrode the oxidization way and in a sence protects it. then rechrome it or paint it. the other idea is to use phosphoric acid to clean the part of oxidization and rince it off with water. Alex Link to comment Share on other sites More sharing options...
Mo's70MCs Posted April 13, 2006 Share Posted April 13, 2006 Wallaby, I remember while working for Mcdonnell/Douglas, and working with untreated 2024 aluminum which corrodes in less than 24 hours if left untreated, using (alodine) a chemical application of a protective chromate. Usually used on small parts that required surface protection after working or sanding, don't now if it will work on Zinc Die- Casting (pot metal) How about using this! Pot Metal Primer. link Rod Link to comment Share on other sites More sharing options...
wallaby Posted April 14, 2006 Author Share Posted April 14, 2006 Hmmm...I wonder if a dab of Zinc-Chromate primer might work? Of course the areas where this is happening is the inside surfaces of my grille. You know, the gaps between the teeth. I want to repaint the grile and I don't want the darn corosion to continue under the paint. They talk about soldering holes in potmetal but that sounds pretty scary. I think the potmetal and the solder have close to the same melting point...and still there is no mention on how to prepare the surface other than drilling out the affected area. I guess it'll have to be fixed like a cavity in a tooth; I can't just put something over it. Here is some additional help: http://www.matronics.com/rv-list/hovan/tips/AlAnDef.html I see that DuPont calls it 225S cleaner and 226S conversion coating. Most of these treatments are meant for aluminum. I should check at my local auto paint supply. Link to comment Share on other sites More sharing options...
Mo's70MCs Posted April 14, 2006 Share Posted April 14, 2006 Cool on the definiton of alodine and makes for a good read! Kinda refreshes the old noggin, because I forgot to mention the staining capabilities of the "Alodine" process.. it required a quick rising right after you stain the surface! I could see it working wonders if you?.. prep the surface! dip the entire grille, quickly dip it again in a water bath? The way it was used primarily; pretty much on small scale and only the surface of the item, where the amount of alodine needed not on large scale.. I mean small amout (1gal) would probably treat the entire surface of a car if it were made of aluminum. I think the process was done because most of the time sanding the surface of Alclad would require reprotecting the surface of the metal, although aluminum is wonderful corrosion-resistant alloy it's not impervious to the elements? Including Riffraff! Rod Link to comment Share on other sites More sharing options...
wallaby Posted April 15, 2006 Author Share Posted April 15, 2006 Here is something else I just stumbled across: http://www.caswellplating.com/aids/solderit.htm This site has some pretty neat stuff. All kinds of home-plating kits and whatnot. Link to comment Share on other sites More sharing options...
Heckeng Posted April 15, 2006 Share Posted April 15, 2006 Aren't all of the potmetal (aluminum mainly) pieces used on our cars chrome plated? Therefore corrosion is not an issue? I'm probably forgetting some parts that were plain or something. If you are talking about pitting beginning and creating a bump under the chrome plating, I believe that is caused by hydrogen being trapped in the cast metal during the pouring process and then working it's way out after the part has been chromed. The hydrogen moves until it hits the chrome then bursts through. Link to comment Share on other sites More sharing options...
Guest Posted April 15, 2006 Share Posted April 15, 2006 Let us not forget that chrome plating can chip thus making the potmetal a magnet for the corrosion. Link to comment Share on other sites More sharing options...
FOOLISH Posted April 16, 2006 Share Posted April 16, 2006 Hey Everyone, In the new Chevy High Performance Mag there is an article called Shine Brite and it covers anodizing pot metals and the company that does it in california. http://www.anobrite.com and scroll down to king of trim. Seeya, Foolish Link to comment Share on other sites More sharing options...
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