Rust Bluing

[Olle]

Originally Posted by timn

Most all early rust blued pieces were polished to 320-400.
I'm talking about a true polished surface. A piece of steel actually polished to a 400 grit finish should be very shiny.

There seems to be some confusion regarding the grit sometimes, and I'm not really sure that all grits are the same (paper, compound, abrasive pads etc). Are you talking about P400 paper or polishing compound?

I use paper and elbow grease for most of the polish (I don't trust myself with power tools around guns), but a fresh P400 paper gives me a brushed finish. It still seems to be a good base for the bluing, after a few cardings you can't see it anymore. I have even tried a light blasting with aluminum oxide, and it did require a heavier carding but came out almost as smooth as a 400-600 grit polish.

It would also be interesting if someone could elaborate a bit on how to get different colors. The only variation I have seen has been because of the steel quality, but some say that you can get different results by using different chemicals.

[nukem556]

THATS the $64,000 question...how to get that elusive true blue you see on early Lugers...I haven't seen any commercial solutions that match it, theyre all a lot blacker. Those who can replicate it won't tell anyone else how they do it. Also, on older Lugers you can see the grain of the polish in the metal, which usually disappears after a few cardings with modern solutions.

[Olle]

Originally Posted by nukem556

THATS the $64,000 question...how to get that elusive true blue you see on early Lugers...I haven't seen any commercial solutions that match it, theyre all a lot blacker. Those who can replicate it won't tell anyone else how they do it. Also, on older Lugers you can see the grain of the polish in the metal, which usually disappears after a few cardings with modern solutions.

I just bought a mismatch with a near mint early DWM frame, and the color is a dark charcoal color that gets a blue hue when you oil it. In other words, it's exactly what I get with pretty much any commercial solution. There are some faint polish marks, but they seem to be from the final carding and not from the metal prep.

I'm wondering if the blue color you see on some guns simply has to do with aging. After all, many Lugers are 100+ years old so it's not too far fetched to believe that something has happened to it through the years. Or does the color vary between the brands?

[timn]

Originally Posted by Olle

There seems to be some confusion regarding the grit sometimes, and I'm not really sure that all grits are the same (paper, compound, abrasive pads etc). Are you talking about P400 paper or polishing compound?

I use paper and elbow grease for most of the polish (I don't trust myself with power tools around guns), but a fresh P400 paper gives me a brushed finish. It still seems to be a good base for the bluing, after a few cardings you can't see it anymore. I have even tried a light blasting with aluminum oxide, and it did require a heavier carding but came out almost as smooth as a 400-600 grit polish.

It would also be interesting if someone could elaborate a bit on how to get different colors. The only variation I have seen has been because of the steel quality, but some say that you can get different results by using different chemicals.

Since you have obviously done some experimenting, you have started discovering the "secrets" to a good finish.

When I said a 320 to 400 polish, I was talking about a sandpaper finish.
A true 400 polish with paper should look very shiny. If you you look closely though, you can see the very fine lines left by the paper.
These can be blended somewhat using a carding wheel.

You are right about using a fresh sheet. It will change the way light is reflected. For a glossier finish, use the 400 till the steel is bright. Something else to try, after it's polished out, turn the paper over and polish with the back side.

Bluing steel,or as it once was called, blacking, is a process of rusting. All you are doing is converting red oxide into black oxide.
That is true in rust bluing and hot bluing. It just happens a lot faster in the hot process.

There is no such animal named blue oxide.

In these processes, our only real variable is the way light gets reflected off of the surfaces (polishing) and the alloys in the steel.

There is a true blueing process. It's called carbona or carbonia, depending on who you ask. This is a heat process akin to color case hardening.

Another method is nitre bluing. Again, it's a heat process. The straw colorings you see on Lugers are a variation of this process.

If the surface of your steel is polished out correctly, the final coloring is dependent on the number of "trips" through the rust, boil, card process and the makeup of the steel.

Also, you can not hide any blemishes when rust bluing. Except for color, the appearance of the steel before bluing is exactly the way it's going to appear when blued.

I really wish I could give you a formula or process that works exactly the same way everytime, but it doesn't exist.

The best thing about working on your own guns is there is no rush. If you don't like the result, you can start over and try sanding a different direction or polishing it out more, or less.

Most any good refinish job will have some blue color when oiled. It's simply the way light gets reflected.

Take your time, be patient, ang good luck with your project.

If you would like to see an example of rust blue combined with nitre blue accents, I will post a photo of my 1911.

Tim

[nukem556]

do a search here using member name "chuckc"... he has an interesting thread about rusting formulas......always kind of hard to evaluate by pictures, but he shows a side by side comparison of a few samples with different solutions...it looks to my eye that he did get some subtle differences in color

[Olle]

Tim,

You are making some interesting points that also confirm what I have found. Just as you say, black oxide is black, so the blue color is not really the color of the bluing. It usually appears after you oil it so it's just a trick of the light, much like what you see in a rainbow or an oil slick on water. However, I have seen guns that have a slight blue hue to them even when dry (for example, my FN/Browning 1900) but they have all been quite old. This makes me think that aging possibly does something to the finish, not to the oxide color itself but to its surface. It also seems like machined and unpolished parts often get a blue sheen to them when you rust blue, so I'm trying to figure out if there is a way to prep other parts (by wire brushing, burnishing etc) to get the same result.

I usually do the final polishing with fresh paper, as I want all parts to have the very same finish before I blue them. The grit will wear gradually so I have never had any luck getting an even prep using worn paper, it's either too worn or not worn enough. I usually use fresh 600 for the final polish, it gives the rust a good bite but is still fine enough for the rust to etch away any directional polishing marks.

And yes, I'd love to see a picture or two of your 1911. I have found that a lot of the appearance is in the accents, and I have used temper colors with good results. Nitre bluing is probably next on my agenda and the only reason why I haven't used it yet is the possible safety issues, but I'm hoping to get my shop area closed off so the family (including the £$#¤% cats) absolutely positively can't get access to it.

[nukem556]

I'm still a relative newby here, but I'm pretty sure I havent seen any recent posts by Mr chuckc...anyone know of he's still around?

[nukem556]

Timn , I don't think I can buy into your theory that "all rust is created equal". If this were true, I can't see why gunmakers over the years bothered to concoct complicated formulas to rust blue with. Angier lists many of these in his book....which include substances such as nitric and hydrochloric acids, copper sulfate, ferric chloride, mercuric chloride, and various "tinctures" and "vitriols". If simple rust is going to always produce the same shade of black, you'd think they would have just used a cheap, simple solution of any diluted acid. And if hot bluing is just accelerated rust bluing (which it may be), how do you account for the red/plum color many guns ended up with? I doubt there was a drastic enough temperature difference in the bath to color temper the metal, so it had to be a chemical mixture variation.

Also ,in rust bluing the ferric oxide (rust) is converted to ferrous oxide but the trace elements of the solution are still in the matrix of the finish somewhere.....unless they boil off, which begs the question of why they were added in the first place.....my 2 cents

[sheepherder]

A little bit off-topic, but what solution/brand is best to get the brownish-"patina" finish that all old guns seem to end up with??? I have an old gun with some patina on it; I'd like to do it all in that worn brown coloring...

[Olle]

Originally Posted by postino

A little bit off-topic, but what solution/brand is best to get the brownish-"patina" finish that all old guns seem to end up with??? I have an old gun with some patina on it; I'd like to do it all in that worn brown coloring...

You probably want something like the browning you see on some antique guns. Browning and rust bluing is actually the same process. When you're bluing, you boil the parts in water to convert the red oxide to black oxide so the only difference is that you don't boil the parts.

Brownells and Pilkingtons formulas will usually give me a mix of red and black oxide (some parts turn black already when I apply the formula), so I would try somehing less agressive. You could possibly dilute it a bit as well to avoid the black oxide.

Once you're happy with the finish, you rinse in water and oil the parts. Some say that you also have to neutralize in baking soda, but I'm not so sure that this is necessary as long as you rinse good.