Would Like to Learn about the coatings etc

shootur44

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I would really like to learn all I could about the different types of coatings for steel etc , I have been looking into the dura-coating products some but before I make an investment in all that you would need I would like to check out other coatings and especially about what I have heard referred as Tool Blackening . I am all ears for any info available ,I am plum dumb in those areas , Thanks Mike:thinking::whiteflag:
 
As far as tool blackening aka Black Oxide... It's just a different (earlier) version of gun bluing. Steel is mainly iron (Fe) and when exposed to air, the diatomic oxygen (O2) in air combines naturally creating FeO2 -simply known as rust! Well, there are other types of oxidation where the iron and oxygen contain other elements. Copper is one of the other elements commonly used but, there are many others which give different hues and colors. The nice thing about the other elements is that once they are in place, additional normal rust cannot molecularly combine and thus you get a stable surface treatment.

Most oxidizing treatments contain acids (sulfuric, nitric, phosphoric etc) which etch the surface allowing other inert elements to combine. There are many ways to skin the cat and sometimes it's done with single chemistry or multiple steps.

I use Casewell black oxide (see the thread about "Mystery Project) which has the oxidizer (acid) and copper solution in the 1st step and a sealer (which is just a penetrating oil) as the second step.

Aluminum coatings are pretty-much the same but not only are chemicals needed to etch, an electrical current is needed to force the inert coating to bind at an atomic level.

For these type of coatings, the word coating is a slight misnomer. It's not really coating, its changing the chemical structure of the exposed surface. For all practical purposes, most coatings of this type have no measurable change in dimensions -unless you have a micrometer that can read the orbit diameters of electrons around a nucleus.

HTH... Ray



I would really like to learn all I could about the different types of coatings for steel etc , I have been looking into the dura-coating products some but before I make an investment in all that you would need I would like to check out other coatings and especially about what I have heard referred as Tool Blackening . I am all ears for any info available ,I am plum dumb in those areas , Thanks Mike:thinking::whiteflag:
 
Thanks so much Ray. Great info there- I haven't blue'd something since I rebuilt a 20 guage shotgun twenty-five years ago. Hah - I forgot it was that long! My Dad still hunts with it.

Has anyone out there attempted Parkerizing? It sounds nasty to basically almost boil phosphoric acid. And there are some kind of tolerance issues- but also creative plugging, and pre-planning machined surfaces, that would be built up (like when anodizing) would work.

I have read that it is a very durable surface. Just nasty to "apply"


Bernie
 
Got a Question for you ??

QUOTE=shootur44;124224]I would really like to learn all I could about the different types of coatings for steel etc , I have been looking into the dura-coating products some but before I make an investment in all that you would need I would like to check out other coatings and especially about what I have heard referred as Tool Blackening . I am all ears for any info available ,I am plum dumb in those areas , Thanks Mike:thinking::whiteflag:[/QUOTE]

Ray I want to THANK YOU for the info and lesson , you know I believe a person can learn something new everyday -- but in my case the 1- thing I learn , I forget 2 things.
Seriously thou --THANKS , I want to continue to follow and learn as much as possible about all the diff coatings and finishes so I DO APPRECIATE YOU SHARING YOUR KNOWLEDGE . Mike

QUESTION ????
Ray as far as tool Blackening goes -I saw a bottle of what was basically naval JELLY TO REMOVE RUST , I STARTED READING THE INGREDIENTS AND IT WAS BASICALLY phosphoric acid and I was wandering if you rubbed or painted it on a piece of steel would it do the same as the "tool Blackening that you pay so much for and it the same basic ingredient ???????
 
Re: Got a Question for you ??

Hi Mike...

You're welcome.

If the bottle of stuff you have also contains trace amounts of copper, selenium or other "tinting" elements then, yes, it might do something along the way of providing an oxidized surface. I tend to think however, it will just etch the surface and predispose it to air contact and thus make it rust with the undesirable type of rust we battle with.


Ray



QUOTE=shootur44;124224]I would really like to learn all I could about the different types of coatings for steel etc , I have been looking into the dura-coating products some but before I make an investment in all that you would need I would like to check out other coatings and especially about what I have heard referred as Tool Blackening . I am all ears for any info available ,I am plum dumb in those areas , Thanks Mike:thinking::whiteflag:

Ray I want to THANK YOU for the info and lesson , you know I believe a person can learn something new everyday -- but in my case the 1- thing I learn , I forget 2 things.
Seriously thou --THANKS , I want to continue to follow and learn as much as possible about all the diff coatings and finishes so I DO APPRECIATE YOU SHARING YOUR KNOWLEDGE . Mike

QUESTION ????
Ray as far as tool Blackening goes -I saw a bottle of what was basically naval JELLY TO REMOVE RUST , I STARTED READING THE INGREDIENTS AND IT WAS BASICALLY phosphoric acid and I was wandering if you rubbed or painted it on a piece of steel would it do the same as the "tool Blackening that you pay so much for and it the same basic ingredient ???????[/QUOTE]
 
BTW: I'm hoping others chime-in about different metal finishes as, I have very limited knowledge about the different techniques. My knowledge only goes as far a black oxide and whatever I can surmise based on some formal education in chemistry (which was admittedly my weakest area).

Ray
 
I don't claim to be an expert at using this stuff. But I've been around and have used it, written specifications for its application, for what is called Manganese Phosphate coating. Most everything I've dealt with in the real world in the past 35 years has some kind of phosphating applied to it.

There two types of phosphate coatings. 1) is Zinc phosphate and 2) Manganese phosphate. The only difference I've ever seen between the two is the zinc phosphate give a lighter gray coating while the manganese phosphate is a much darker gray to black coating.

For either one to be applied to a surface properly, the solutions should be heated. It does work without heat, but the adhesion rate is very slow and does not coat evenly. The parts must be cleaned with a soapy water solution, rinsed, and run through a solution that helps activate the phosphate solution.

There several websites that deal with phosphating, from doing it for you to sources for buying the stuff to do it yourself, to just learning about the stuff.

One site I ran across is http://www.phosphating.net/manganese-phosphating.html . There are others, just do a search! There's also some video's on YouTube too.
 
I haven't done it for a while but Manganese Phosphate "parkerizing" is relatively easy although relatively expensive if you are doing small quantites. Chemicals are available from gunsmith supply sources, Brownell, Midway, etc.. I used SS steam table pans on hot plates and a candy thermometer. Like all finishing projects prep is the most important step.
 
Here's a simple, low temperature method for true black oxide. The only chemicals involved are hydrogen peroxide, salt and boiling water.

 
Yes - something acidic to pickle the surface, and clean any loose hydrated iron oxides (Fe2O3·nH2O) i.e. "flakey rusts" away, to first get a blotch-free surface. Now the game is to lay on some high adhesion rust Fe2O3 and convert it to another kind of "rust", Fe3O4 , called magnetite.

Without adding in any other elements, just boiling in water, or promoting a high adhesion corrosion with a powerful oxidizer like peroxide, makes, a (thin) coating of magnetite, and it can end up gun-metal blue-black colour. It blocks the direct exposure of iron to wet air. In doing this, you have to follow through until you have the coating. Any iron that has seen any acidic cleaning will turn orange before your eyes in seconds. This also happens if you have been steam-cleaning. Leave the stuff under the liquid, or get the process to continue until the surface is protected. The recipes vary, but this intermediate stage always leaves the iron/steel vulnerable.

Without going into the generally complicated chemistry of iron oxides and hydroxides (the flakey stuff), or the zillions of recipes for adding in other solutions or heat processes to get a special color, in general these coatings are stable, but not really permanent. If you seal it with a penetrating oil, you have a very durable blue-black surface. This is not to be confused with "rust converter" products that use phosphoric acid to pickle off the rust, and then cover in some of their own oxide (ferric phosphate). It's also blue-black.

We recognize a mad mixture of all these oxides, including magnetite as mill scale. A fresh mill scale is hard, and protective, and if sealed, can be attractive, but if left to itself, it will rust through and fall off. The stuff is quite useful, until you want to weld on it or machine it.
 
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