Rust question

W

Whoever Wherever

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Nov 17, 2006
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OK, dont ask me how I got into this mess. Lets just say some ol' timer sourdoughs are hard to say no to. Long story short I am refurbishing an old knife. Problem is its covered in rust (I know, I know but it was his dad's homemade knife) and I dont know how to proceed.

First I hit it with naval jelly, worked for some of the rust. Tried that a few times, then I hit it with a fine grit sandblast. That moved alot more and now I am down to some whats left in the deep pits that just wont blast away. I wanted to get most of the rust before cleaning it up on the belts because theres not a whole lot of knife left. Any suggestions? Is there a way to neutralize the remaining rust and then get a good mustard or an etch patina going to protect it while blending in the color of the remaining rust?

In the future I will avoid such projects like the plague, hehe. Thanks for any help.

Dustin
 
what about media blasting it? sandblasting with something that is not as harsh as sand, I mediablasted a blower I was working on for a car where my tollarances had to be kept and it did a wonderful job, when I worked in a machine shop we would have to change the sand because it breaks sown and does not cut as much as new sand try your local head shop
 
Google "electrolytic rust removal" you'll need a decent sized DC power source (automotive 12v battery charger) but it will remove all the rust without taking away any of the remaining base metal.
 
Phosphoric acid will convert the rust to a black iron oxide. Is the blade separated from the handle?? If you soak it in the Phosphoric and then boil the blade it will set the oxide and you can hit the high spots. Kind of like a rustic finish.... If it were not an item from your father I would suggest starting with a new blade....
 
Thanks guys. I use crushed glass sand so that may not be helping. The electrolytic sounds good, should have payed more attention to Mr. Wizzard. The phosphoric sounds like it would work to. I'll do a little research on the two and go from there. The knife is for a good friend and belonged to his father. I would much prefer to make a new blade but I am stuck with this job so I want to do the best I can.

Dustin
 
Naval jelly is phosphoric acid in a gel .There are proprietary compounds that convert rust to a stable for to prevent further rusting.
 
So what I am percieving as left over rust in the pits is actually black iron oxide. If thats the case I should be good to go, right? Would a patina protect the iron oxide as well as the rest of the blade? Thanks again for the input.

Dustin
 
a patina is broadly defined as an oxide layer on metal vis a vis rust.
if you are down to black oxide in the pits that is a somewhat stable version of rust. Kevin Cashen had a recipe for neutralizing after etching damascus involving sodium bicarb and hydrogen peroxide that someone pointed out was suspiciosly like rust bluing, which would be a nice finish and would neutralize the phosphoric acid residue in the pits. if you want to keep it pretty much as is, there's a product called renaissance wax that museum curators use
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