Home Forums Hunting & Shooting Gunsmithing Slow Rust Blue Question

I'm doing my first piece using this method and am puzzled why, when I take the pieces (revolver) out of the boiling water, they are covered with soot. Where is that coming from? I've never heard of anyone else encountering this. What am I doing wrong?

I believe it is an oxide that needs to be carded off. It's a normal part of the process.

Paul

That would be great, if true. Not one of the YouTube videos mention this soot. I found, on this last go round that it comes off much more easily if you get on it as soon as the part comes out of the hot water.

I don't know what Youtubes you found, but in a quick search I hit one by Larry Potterfield, scanned through it and saw how boiling turns the red rust to black and produces a black velvet which he takes off with steel wool and a fine wire wheel. That's been standard practice for over a century. Isn't that what you're talking about?

It's supposed to look like black soot. The boiling converts the red oxide rust to black oxide rust.

Ah, it's just me not understanding what to expect then. I was expecting the conversion to be just a hard black substance. The first time I boiled, much of the surface area just turned black and only about 40% or so developed this soot, so I thought the hard black areas were the norm, not the sooted areas.

Assuming you do it correctly, each step or coat gets better and better. You just stop when it looks as good as you want it.

It's not difficult, just takes patience, and it's well worth the effort, IMO.

Paul

You should have a uniform coat of "soot" over the entire area you coated with the rust blue solution. If not, you are doing something wrong. Most likely the metal was not clean enough in those areas that did not develop the soot, but I'm guessing. The metal must be chemically clean before coating with the blue and must remain that way while boiling, carding, and recoating as you go thru the process. Most over the counter rust blue solutions cannot cut through the skin oil in a fingerprint and rust will not develop properly. There is a way around this problem, but I won't go into it unless you want me to.

RAN

Ran - absolutely go into it. So I had it just backward about the soot and the smooth areas? I don't know if it matters though since once carded they looked about the same.

Now I don't rust blue but have worked with ferric chloride and copper sulfate solutions. If your "panther piss" includes those chemicals odd things can happen. Can also be an artifact of trace elements in your water. I would be interested in how the finish is coming along and try to ignore the smut.

I've learned some things doing my first firearm (in addition to the soot being normal).

1) Don't polish over 320 grit sandpaper (maybe 400 grit). The rougher grit makes the bluing take better. The rough inside of the frame blued up with the first application.
2) On the first application, instead of making single straight swipes, go over the metal hard and in circles, repeatedly.
3) Put the rust solution on thinly. The smoother the surface, the harder this will be to do.

One thing I tried, that I think worked, was to put the solution on and then let it dry outside in the sunlight, and then take indoors to hang in a moist hot environment.

What solution were you using? I've found Laurel Mountain Forge to be very forgiving in my own limited experience.

The problem of handling and maintaining absolute cleanliness can be eased by using Laurel Mountain Forge Barrel Brown and Degreaser: https://laurelmountainforge.com/barrel_brown.htm
It contains a detergent and will allow barehanding( with clean hands) the metal while coating, boiling and carding. This is a huge advantage especially when using a powered wire wheel. A heated damp box is good if you live in a dry climate. 90 deg. F and 90% humidity will produce uniform rust in a few hours. All wire brushes for carding should have wire .005" dia. or smaller. If you use a powered 6" wire wheel, don't exceed 500 RPM. Boil in distilled water. It is cheap and readily available. Low and medium carbon steel like a barrel will usually develop a good blue in 4- 6 cycles. 4140 like a modern receiver will take 6-7 and won't get really dark blue because of the chrome content. The entire coated area should have a uniform black rust coating before boiling. 5 min. is plenty for boiling time. When starting out, always apply the first coat over a freshly polished surface. The reason is that an aged polished steel surface will develop a thin, transparent iron oxide film that inhibits the first coat's chemical activity. Don't want that. A fine( Gray) grit Scotch Brite pad will do the job just before the first coat of blue.

RAN

I have used the laurel Mountain brown for browning and it's wonderful stuff. But I try to do the superclean drill and consider the capability of the solution as insurance and I've never been disappointed. Now I have gotten overly aggressive with the damp box and got a coarser brown, not the fine rust you're looking for - start all over.