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The Black Knife always triumphs!


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Wes,

 

truly a beautiful knife, btw, was that you I saw in a popular knife magazine?

 

the only things I could add to the rust bluing process is use rock salt or kosher salt rather then table salt and keep adding salt and peroxide as it boils down and earl grey tea works the best for turning steel black. anything else I do, might be considered a little too far fetched, so I'll keep that to myself lol

 

R

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/r/changemyview all time top... www.reddit.com/r/changemyview/comments/4k83qf/cmvstrange_women_lying_in_ponds_distributing/

 

Haha, I guess it could have some merit...

 

 

 

I love it. I won't beat the Holy Grail thing to death, although i even manage to work, "Now you see the violence inherent in the system," into my psych and law classes.

 

Ricky never comes here any more, he has been rust bluing to good effect for the last couple of years. He may add something, if he ever comes around.

 

kc

 

Thanks Kevin, I'm glad you like it. Please, by all means, beat it to death. Or you can quote "The Life of Brian" or any of the Monty Python skits (my personal favorite).

Ricky lurks quite well; I know because we have an ongoing PM conversation :) Rust bluing is actually the first thing we ever had a conversation about, so I am glad he decided to weigh in.

 

 

Wes,

 

truly a beautiful knife, btw, was that you I saw in a popular knife magazine?

 

the only things I could add to the rust bluing process is use rock salt or kosher salt rather then table salt and keep adding salt and peroxide as it boils down and earl grey tea works the best for turning steel black. anything else I do, might be considered a little too far fetched, so I'll keep that to myself lol

 

R

 

Thanks Ricky! i appreciate the compliments :) That is correct; I am in the September issue of Blade Magazine, which is the one on newsstands now. The Rosewood skinner I showed on here a few months was sent away to Kim Breed and he did a review of it. It did quite well, and Mr. Breed said some nice things about the knife.

 

I do the same, I am always adding more peroxide and salt. As you said, it boils away and after a while seems to stop reacting as well. I have only ever used table salt and the most generic black tea. Have you had better luck with rock salt and Earl Grey? On a side note, I love Earl Grey tea.

Edited by Wes Detrick
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Wes, about that rust bluing. This new learning amazes me sir. Explain again how ram's bladders may be used to prevent earthquakes.

 

You can also find muriatic acid in one-gallon jugs at Home Depot, Lowes, or pool supply stores. It's the acid most often used for lowering the PH in pool water. For those of you who don't want to keep buckets of this stuff in your shop, try a dry pool acid called "PH Down". It comes in a bag and you mix it with water to whatever strength you desire. That's what I use to clean the forge scale off when it gets too thick.

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whoa! thats amazing! what is the air-speed velocity of an unladen swallow?

 

European or African? :) Thanks!

 

 

 

Wes, about that rust bluing. This new learning amazes me sir. Explain again how ram's bladders may be used to prevent earthquakes.

 

You can also find muriatic acid in one-gallon jugs at Home Depot, Lowes, or pool supply stores. It's the acid most often used for lowering the PH in pool water. For those of you who don't want to keep buckets of this stuff in your shop, try a dry pool acid called "PH Down". It comes in a bag and you mix it with water to whatever strength you desire. That's what I use to clean the forge scale off when it gets too thick.

 

Hahaha, as soon as I figure that one out, you will be the first know!

 

What do you do with the remains of the acid once you have removed the scale, and don't want to keep it around anymore?

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What do you do with the remains of the acid once you have removed the scale, and don't want to keep it around anymore?

 

Pour in either baking soda (sodium bicarbonate) or washing soda (sodium carbonate) until it stops fizzing. That neutralizes any remaining acid and gives you a relatively nontoxic slurry of off-white to blackish goo that can be watered down and poured out. Or, going back to chemistry 101, hydrochloric acid saturated with iron oxide results in ferric chloride! HCl + Fe3O4 = FeCl + H2O.

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Pour in either baking soda (sodium bicarbonate) or washing soda (sodium carbonate) until it stops fizzing. That neutralizes any remaining acid and gives you a relatively nontoxic slurry of off-white to blackish goo that can be watered down and poured out. Or, going back to chemistry 101, hydrochloric acid saturated with iron oxide results in ferric chloride! HCl + Fe3O4 = FeCl + H2O.

 

Hmmm, I can see how this new fangled alchemy thing might be useful in the future... thanks for the info Alan!

 

 

Huh? I dont know that. Wes how do you know so much about swallows? :lol:

 

Monty Python taught me everything I need to know!

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Pour in either baking soda (sodium bicarbonate) or washing soda (sodium carbonate) until it stops fizzing. That neutralizes any remaining acid and gives you a relatively nontoxic slurry of off-white to blackish goo that can be watered down and poured out. Or, going back to chemistry 101, hydrochloric acid saturated with iron oxide results in ferric chloride! HCl + Fe3O4 = FeCl + H2O.

So I can take my forge scale and just add it to my muriatic and it will make Ferric Chloride? Is there a weight ratio?

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Chemistry my friend... just figure out the # of mols of HCl you have and then find out how much that many mols of forge scale you need and then convert that to weight.

 

Here is my go at this... I haven't done this in a year, so I might be wrong...

 

Molar mass of HCl is 36.46g/mol. 1g=1mL

1 L of HCl is 27.42 mols.

 

8HCl + Fe3O4 => FeCl2 + 2FeCl3 + 4H2O

 

So you need 27.42 mols of Fe3O4

The molar mass of iron (III) oxide is 231.53 g/mol meaning that you need 794 g of scale per liter of HCl

 

But don't count on my chemistry skills right now .....

Edited by Timothy Artymko
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Chemistry my friend... just figure out the # of mols of HCl you have and then find out how much that many mols of forge scale you need and then convert that to weight.

 

Here is my go at this... I haven't done this in a year, so I might be wrong...

 

Molar mass of HCl is 36.46g/mol. 1g=1mL

1 L of HCl is 27.42 mols.

 

8HCl + Fe3O4 => FeCl2 + 2FeCl3 + 4H2O

 

So you need 27.42 mols of Fe3O4

The molar mass of iron (III) oxide is 231.53 g/mol meaning that you need 794 g of scale per liter of HCl

 

But don't count on my chemistry skills right now .....

I'm going to have to count on your chemistry skills.

I went to high school for 5 years and didn't graduate.

We'll say its a little over my head.

Except I can convert the grams to ounces and the liters to gallons.

Thanks,

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I think the liters to moles conversion depends on the concentration; HCl is actually a gas dissolved in water, so it comes in various concentrations unless you buy it as a gas (unlikely). I think if I recall correctly, concentrated HCl is around 37% or 12 molar, while what you can buy as pool chemicals etc. is usually already diluted somewhat. So check the label, then convert percent to molarity if molarity isn't given, then figure liters of HCl to react with moles (convert to grams) of iron.

 

Another way to think of this might be, how much rat has it got in it? :)

Edited by Michael Stuart
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I remember the rat story!

 

No need to overthink it, you are adding scale until it won't take any more. I can't promise it'll be clean etching, or that it won't be a funkadelic failure, but n theory it should work. It'd work better starting with reagent grade HCl and pure iron powder, of course.

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Yep, as long as you strain out the grinder grit, which of course may affect the etching abilities on its own. I mentioned the chemistry as a curiosity, not as a great new source for ferric chloride. I'm not sure of the resulting concentration or of the effectiveness of homemade, which is why I stick with the store-bought stuff.

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Yep, as long as you strain out the grinder grit, which of course may affect the etching abilities on its own. I mentioned the chemistry as a curiosity, not as a great new source for ferric chloride. I'm not sure of the resulting concentration or of the effectiveness of homemade, which is why I stick with the store-bought stuff.

So unless you are one of those modern day prepper people........

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Could you use the pile of dross left under your grinder instead. Because I have loads of that.

 

I imagine a strong magnet would be great at this. And even if you don't make your own Ferric Chloride, the swarf could be used if even make canister damascus or your own steel. Maybe... correct me if I wrong here guys.

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I imagine a strong magnet would be great at this. And even if you don't make your own Ferric Chloride, the swarf could be used if even make canister damascus or your own steel. Maybe... correct me if I wrong here guys.

I've been saving it for that very purpose. I think I have 4 of those smaller Gatorade cans packed full of it.

So, I hope it would work.

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I'm letting my grinder swarf turn back to ore before smelting it. At least that's how I explain the big wads of rust by the back fence to my wife...

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I hadn't noticed this had turned into a chemistry thread. I did a pretty involved lab and writeup about basically this exact reaction a few months ago. It turns out that scale and pickling, which is pretty much the same reaction as making ferric and ferrous chloride from scale/swarf, is pretty interesting (at least to me). Scale actually consists of three different types of iron oxide, the inner most being FeO (wüstite), then a layer of Fe3O4 (magnetite or black oxide) and finally an extremely thin outer layer of Fe2O3 (hematite, or red oxide). When you submerge it in a strong acid, the hydrogen ions react with the lattice in a way that they free iron ions at the surface to dissolve into the solution and form water with the oxygen ions.

 

There are different types of iron oxide because iron tends to form two different types of ions, Fe2+ and Fe3+. FeO has Fe2+, Fe2O3 has Fe3+ and Fe3O4 contains a mix of both in a 1:2 ratio. Fe2+ ions can actually react with Fe3+ ions on the surface of a piece of oxide in a way that busts them out of the lattice (reductive dissolution), so Fe3O4 dissolves the fastest of the three different types of oxide because as soon as some of it is in solution, it starts almost dissolving itself.

 

A consequence of iron's ability to form two different oxides is that there are two types of iron chloride: iron (II) chloride (ferrous chloride) and iron (III) chloride (ferric chloride), both of which form from dissolving scale in HCl, forming a solution referred to as iron (II,III) chloride. The composition of scale or grinder swarf likely varies greatly, but, at least with mill scale, you would expect there to actually be a bit more ferrous chloride than ferric. In this sense, home made iron chloride would be somewhat chemically different (and likely a measure less "aggressive" as an etchant) due to the presence of Fe2+ ions.

 

Something to keep in mind about these reactions though is that they are very slow. The reaction mechanism is fairly complicated with several steps and since it takes place on the surface of a solid, the rate is further limited. Using smaller particles (the powder from under a belt sander vs. the flakes of forge scale) would help mitigate this, but it is still very slow. When I was investigating the reaction (and I used magnetite with particles around the size of flour), there was no noticeable pH change out to the hundreds place after an hour. I had to switch to spectroscopy (its whole own can of worms) to be able to quantitatively measure the reaction at all.

 

Wow, that's a wall of text. Sorry if this is too chemistry-ish/boring, this topic is a hammer I spent about six months researching and writing a paper about and it felt like I might have found a nail. I hope some of this was interesting/educational. I'm by not an expert, just interested in the topic and if I got something wrong don't hesitate to correct me.

 

TL;DR, iron forms two types of oxide which dissolve in HCl to form two different types of chlorides, one of which is ferric chloride like you would buy and the other ferrous chloride which is 2/3 less effective as an etchant. The reaction mechanism is complicated and slow, so expect to wait a while if you try making your own.

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I never mentioned it, but I love this knife Wes!!

 

Haha, thanks Timothy. It got lost for a while in there because of the chemistry lessons :) (not that I mind them of course)

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