ferric for corrosion resistance?

J. Neilson

J. Neilson

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Feb 6, 2001
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I have a customer that is thinking about a ferric etch on a blade for corrosion resistance and wanted to know if it would help. I've used plenty of ferric chloride but, I never thought it would protect the blade. Anyone have an idea on this one?
 
If he wants corrosion resistance, I would say parkerizing. That's doable at home.
I really don't know if Ferric Chloride imparts any rust protection to steels soaked in it. But, I have my doubts.;) :D
 
The secret is in what you do 'after' the etch J. After you get a nice etch on the steel, buff it with fine steel wool just enough to take the 'rough' off of it. Then boil the blade in baking soda water for at least 15 minutes. That 'sets' the oxides and becomes a barrier for rust once it's oiled down (it also neutralizes the ferric chloride). I use Ballistol for the best results. Every damascus blade I forge gets that baking soda treatment. It works great and really sets off the contrast in the pattern.
 
I have used FC on a carbon steel kitchen knife for rust protection and it worked good, just a quick etch and clean off. The knife was used for several years and was used no extra care and never showed any sign of rust. Gib
 
Originally posted by MaxTheKnife
... Then boil the blade in baking soda water for at least 15 minutes. That 'sets' the oxides and becomes a barrier for rust once it's oiled down (it also neutralizes the ferric chloride). ..
Click to expand...

That's a pretty neat idea Max;) . But it is worth a mention that ferric chloride corrodes from two different directions. First, it does have a HCL base to it so it is slightly acidic, and the baking soda will kill that, but the baking soda cannot help with the second line of attack- chlorine. But I have found that the boiling in bakin soda water will kill both. You see to get rid of that nasty chorine affect you need to just plain rinse like crazy to clean all of the Cl atoms off the steel and boiling seems to do the trick.

So you are right with the boiling in a baking soda solution, but I wanted to make the further points before somebody jumped on the idea that baking soda alone would nuetralize FeCl, as they always do when I describe the process.

I have a old FryDaddy that my wife discarded that sets in my shop full of a baking soda solution, just for damascus fittings, works real nice ;) .

P.S. How have you been Max?!
 
Good thread!

A couple of questions on procedures... What would you guys recommend for the mixture of the ferric chloride and the soak time in it. Do you just let the blade sit in it or agitate/stir while the blade is in it? Would soak time and strength of solution vary depending on the type of steel being etched? What is the mix of baking soda water that you boil the blade in?

Thanks,
Rick
 
By no means am I a knife etch expert, but on the question of agitating the solution I used to design electronic printed circuit boards and the pro's that etched then sprayed the solution on them to etch. In etching more simple boards at home I would occasionally stir up the solution.

RL
 
For my ferric etches I started out using a fish tank "bubbler" (don't know what you really call them). This made for a faster etch. Later on I stopped using the bubbler believing that the slower etch would be cleaner looking. (Opinions?) I use a 1/3 mix of ferric to distilled water and hang the blades in the mix. On damascus I usually etch about 15-20 min. but, when I'm just trying to bring out the temper line and nice ferric "tint" I'll only leave it in for about 5 min.

I use a large stock pot and dump about 3/4 of a cup of baking soda for boiling solder joints but, never used it for ferric etched blades. I've always cleaned them with Windex w/ ammonia and I haven't had any problems, so far, with this method.
 
I just dipped the blade in the FC till I got a gray color to suite me then washed it off with the hose. The FC started out as a 4 to 1 mix. Gib
 
Great thread folks!

One question, can you use this stuff around a finished knife. I got my Daughter a new kukri and I was trying to decide how to finish it?
 
You sure can, I've done it before on high carbon steels. Just tape off the handle/guard and make sure the blade is clean. You can take some straight ferric (on a clean cloth or cotton ball) and wipe down the blade a few passes. Then sparay the blade down thoughly with Windex w/ ammonia. You'll get a nice patina tint to the steel and a temper line if it's edge quenched. Try it out on some scrap steel first, if you can, just to get the hang of it.
 
I sell cleaners, deoxidizer and of course phosphate for a living. I service a lot of platers and I'm impressed with the level of alchemy I just read. Every point was dead on from the etch to the Cl issue. Not sure if TSP would be better then Baking soda and don't know about the boiling part. But even if a small improvement was made I don't think it would effect the end results.

My hat is off to you all,

Joe
 
Hey Kevin, thanks for the comments old buddy! It seems like I always need a cleanup crew to come in behind me and fix the mess I make. He he. So what you're trying to say is that I've been doing the right thing I just didn't know why it was right? Makes sense to me. I find out most things by accident just because they work. I got the boiling in baking soda water thing from my step-dad and teacher Mr. Ogg (he added dish washing liquid). He always boiled his blades after the heat treat because it helped get the hardened oil off the blades without having to go back to the satin finish wheel. I just added the baking soda as a neutralizer for the ferric chloride. It just made good sense. And I noticed that it also 'set' the oxides as a permanent finish. Even sandblasting won't remove it all!

By the way, I'm doing pretty good Kevin. How are things going for you and yours?
 
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