When is "Free" scrap metal not a good deal???

[ak9]

MossflowerWoods

20+ years ago I unknowingly bought a 20 arce"farm" that really was a auto/farm/coal mine junk yard. I've been digging /rototilling up stuff for quite a while .I built a few metal storage racks outside using scrap to aid in organization. I save thicker/longer stuff and sell/scrap the smaller thinner stuff .
If you do choose to get rid of the thicker metal put an ad on craiglist first B4 taking to the scrap yard .Structural prepped metal @ me is 14$ =100lb & sheet iron is @$12.5/ 100 lb.I 've bought alot of salvage metal from individuals off of craigslist . In my area the scrap yards do not sell metals out the door any more
ak9

 

[Ken45101]

No, it actually converts the rust by "unoxidizing" it. I doesn't make it back into structurally sound steel, but it converts it into a stabile substance that won't continue to corrode the adjacent metal.

I really, really doubt that it unoxidizes it. That would be taking the oxide out of the iron oxide, leaving pure iron. I'll call BS on that. It takes a blast furnace to unoxidize iron oxide.

I will accept that it seals and bonds to the rust, just like some of the Rustoleum paints or some epoxies.

 

[lostcause]

I really, really doubt that it unoxidizes it. That would be taking the oxide out of the iron oxide, leaving pure iron. I'll call BS on that. It takes a blast furnace to unoxidize iron oxide.

I will accept that it seals and bonds to the rust, just like some of the Rustoleum paints or some epoxies.

i've seen some coatings that are supposed to do more than just bond to it. i agree that it probably isn't removing the oxidization, but since rust is a chemical reaction i bet it is designed to react with it and create a barrier to keep it from rusting further, rather than just a coating to adhere to it.

this type of thing has been done to varying degrees of success before. there is a type of steel called a588, also known by the trade name of corten that is a weathering steel often used in bridges and exposed structures. i never read the data sheets on it, but my understanding was that when exposed it would rust and create a barrier that would not rust further. my understanding was also that it didn't work as well as advertised.

 

[k0ua]

When applied to rusted surfaces, OSPHO causes iron oxide (rust) to chemically change to iron phosphate - an inert, hard substance that turns the metal black


Still not what you want to weld to being iron phosphate. But it does chemically change the rusty metal into something else.. and as noted, it is something you can now paint over.

James K0UA

 

[slowzuki]

The yards here are paying about 0.10$ a lb. Good scrap they are selling at 0.40$ a lb. New is 0.65$ a lb and up. I don't take it in for scrap unless its pretty bad shape.

 

[Ken45101]

this type of thing has been done to varying degrees of success before. there is a type of steel called a588, also known by the trade name of corten that is a weathering steel often used in bridges and exposed structures. i never read the data sheets on it, but my understanding was that when exposed it would rust and create a barrier that would not rust further. my understanding was also that it didn't work as well as advertised.

That is basically how aluminum protects itself. Fresh aluminum oxidizes and creates a sealed barrier to further oxidation.

Ken

 

[Iplayfarmer]

I really, really doubt that it unoxidizes it. That would be taking the oxide out of the iron oxide, leaving pure iron. I'll call BS on that. It takes a blast furnace to unoxidize iron oxide.

I will accept that it seals and bonds to the rust, just like some of the Rustoleum paints or some epoxies.

That's why I put quotes around "unoxidizing". You're not actually removing the oxygen, but you're changing the oxidation state of the iron ion and bonding it with phosphate (that's where the oxygen is now). See K0ua's post above. There are probably other molecules that would work too besides phosphate.


I think the point here is that it actually chemically reacts on a molecular level with the rust and makes it not rust anymore. It doesn't just encase or seal the rust where it is. It changes the iron oxide (rust) into a whole different substance.

 

[muddstopper]

All these unoxidizing agents are is really phosphoric acid, you can buy it cheap at major hardware stores, or you can pay high prices for products such as Metal Ready.

To remove the rust from metal and make it look like new, you need to use electrolis. Simple system of a tank large enought to hold the piece of metal you wish to clean. Fill tank with water and a couple spoonfuls of twenty mule team borax, (adding more doent speed up the process). Suppend the steel to be cleaned in the water borax solution without touching the sides of the tank. Connect your battery charger to one end of the metal to be cleaned and the other end to another peice of scrap rebar or steel fragment that you also suppend in the water borax solution, also not touching the sides of the tank, or the piece you wish to clean. It takes a few minutes to start working, but soon you will see little bubbles leaving one piece of metal and sticking to the other piece of metal. You want the bubbles sticking to the piece of scrap you wont be using. If bubbles are traveling the wrong way, just reverse the battery cables. Lenght of time to clean all depends on the amount of current you can supply with your charger, (must be DC), and how big and rusty the piece is to be cleaned. I've done everything from a old vise to engine cylinder heads and they will look like new metal once done. This process will get rust out of places you cant sandblast clean. Of course this doesnt replace any metal lost thru pitting and the metal will surface rust again if not properly protected once cleaned.