Soo I jusst mixed some mustard and ketchup,  spread it on a rag,  and wrapped it around my Mora classic six inch carbon steel knife.  How long do I keep it wrapped?

Making sure it's even, anywhere from 30 minutes to several hours. Knowing Mora's, I'd say 2 hours is good. Past that if it's not deep enough, just keep going on. I'm not sure what the prices are up at the top of the world, but Ketchup and Mustard isn't that expensive.

I'm new here so I'm kindof curious. Why would you treat a knife blade with mustard?

Little, would that work on firearms as well? I sometimes use browning instead of blueing and it's been a while but I think it was some kind of plum concoction. I have an old .22 rifle, my throw into the back of the Jeep bolt action rifle that got suntan lotion on it and screwed up the 'finish'. I'd like to refinish the barrel and action and now I'm wondering of Frenche's could lend a hand.

It's an old and not valuable rifle outside of me because it's reliable so it may be worth it for me just to try it and if it doesn't work, I'll use a commercial grade finish. I just think it's interesting and something new to try. Thanks for the tip.

not oxidation.  
 
both mustard and ketchup are fairly acidic. So there is obviously some reaction between the acid and the metal that creates a barrier to oxidation - rust is not a good barrier.  
 
the acid in question is acetic acid - vinegar.  
So you could simply wipe the knife with vinegar or mix vinegar with a little flour to make a paste if you don't want to waste condiments  
 
Had a quick look and as far as I can tell what actually forms is iron carbonate which does act as a barrier against oxidation.

Pickled iron. Now it makes sense.

Method for using Qak leaves / tea as the tannin supplier in browning  
 
From:     http://www.britishblades.com/forums/
 
Browning/blackening steel
 
    Hi guys can you help.
    I remember from my days in the conservation lab, the first thing we ever made was iron gall ink.  
Basically wasp galls from an oak tree, lumps of bark mixed with iron sulphate. Hey presto! mix together  
and you have an iron ink compound.
    I was wondering if you could blacken an existing steel blade in a similar manner by dipping it in vinegar  
and then dipping it in a tannic acid containing solution? Would this form a lasting black oxide on a blade?  
I have a great knife that rusts like stink, trying to get a consistant oxide coating on it.
    Thanks
    Sandsnakes  
 
Re: Browning/blackening steel
    if the blade is carbon steel you could put a patina on it, that should stop it rusting and it will give it a  
cool antique look just soak some tissue in vinagar wrap it around the blade and leave it over night.
    ant.  
 
Re: Browning/blackening steel
    Thanks Ant. What i did in the end was to soak it in vinegar and then soak it in the cup of tea from hell,  
entire packet of tea boild for an hour. Blade is now black. I will keep you posted and see if it works.
    Sandsnakes  
 
Re: Browning/blackening steel
    Liberon's Tourmaline black or brown (it says it's for brass and copper but works fine on carbon steel),  
wipe down the alcohol or acetone prior to application to get rid of any grease marks or finger prints first.  
works even better on a warm blade.  
    Simon
 
Re: Browning/blackening steel
 
    the browning solution i used said to boil the blade for 10 minutes at the end. i think it helps set the oxides.  
let us know how you get on.  
 
 
Re: Browning/blackening steel
 
    I just use the tourmaline and then give it a wipe down and a wipe over with rennaisance wax. It's not a totally  
scratch resistant blackening but it depends upon what you are looking for.  
    Simon
 
 
Re: Browning/blackening steel
 
   Its a khurkri from the KH in Nepal. Its recycled car leaf spring, so who knows what grade steel, keeps its edge  
well but rusts like an old bucket. So trying to get a stable oxide coating on the blade. In the end went ancient  
chemistry used by the calligrapher monks and alchemists.
    Brewed malt vinegar, blade soaked over night.
    Boiled in oak galls for about an hour(used tea instead-tannic acid being the thing you need)
    Allowed to dry     Post boiling, soaked human urine (Technically should have been female morning urine, at the time  
they were in short supply so used mine).     Blade now has a hard black deposit all over which is fairly tough. Dont ask
 me what oxide it is, all I can tell you is it works.
    Sandsnakes  
 
Re: Browning/blackening steel
 
    If you want to put an oxide layer on a blade to slow down rusting, why not try ferric chloride? Etched damascus  
blades are supposedly much better at resisting rust than say a Scotchbrite finished blade. Craig Camerer has been  
known to put a low shine "tactical" finish on some of his 1084 blades by first bead blasting them ( normally a recipe for rust)  
and then etching them in ferric chloride. The blade ends up looking kind of like it was parkerized, but without the hassle.  
 
Re: Browning/blackening steel
    Quote Originally Posted by jdm61 View Post
    then etching them in ferric chloride. The blade ends up looking kind of like it was parkerized, but without the hassle.
    That makes sense, a ferric etched logo or "drawing" on a blade holds well and doesn't rust. Nice one,thank you.  
    William
 
Re: Browning/blackening steel
    Ive had very good results using oak leaves(tannins make it work)I just took a handful of oak leaves and boiled them  
in a couple of cups of water.  Put your blades in while hot or boiling.Keep an eye on it,it worked fast for me.Fur traders  
used to blacken their traps like this and I thought it would work well for blades.Im happy with the results and have been  
doing it for a while now.Doesnt cost anything either!