Rust bluing steel

[Naiveambition]

Here you are cogsy, you lucked out that I have a few pieces I forgot and am doing them now:thumbup:

Alrighty then "rust bluing". For those that don't know is taking a clean part and slightly rusting it, or micro rusting it. Then after a period of time in a damp environment, you boil it in water to stop the rusting and turn the red rust into black oxide, you use a soft bristle wire wheel, wire brush or steel wool and "card" the fuzzy layer off and underneath is a lite color change with the oxide taking hold of the metal.

First step is sanding to around 320' . No file marks or they will show. Second step is clean, clean, clean, the part . I boiled it and used brake cleaner before starting.
Third step is to apply rusting agent which is nitric acid and other acids. Wait allotted time 3-24 hrs depending on humidity. Can get rust bluing solution thru brownells, midway etc... There are many different kinds with different methods that achieve the same process. Mostly depends on how long your willing to wait on the finish to achieve its goal.
Fourth step is to boil the part in deionized water for 10-30 min depending on manufacturer instructions. I did use deionized water for the first few cycles and the part maintained a nice luster till switching to tap water.simply cause I ran out due to evaporation. I think this caused my slightly brownish finish under fluorescents but under sunlight it's a nice bluish luster.
Fifth is card the part and don't touch the part EVER without gloves thru the whole process from cleaning to finish.

Now granted you take precautions with the acid when applied to not get into screw holes etc.. It's just a simple wipe of a damp cloth then let it sit. Repeat the process till desired color is achieved and if correct will be a nice bluish black but can vary depending on amount of coats.
From my reading this was the process on all guns before hot rust bluing came into play. Quite simply the amount of time involved with slow rust bluing was the issue that caused the switch. Although it is still used on parts that require soldering. As a hot blue will eat away at the solder, the slow rust blue does not. It will not cover or stick to the solder, but is not affected by the acids.

Here is a part on the left that is cleaned and ready for rusting. Now I chose not to do this part but is here to show where I start. The part on the right has had 3 rusting sessions and is on its 4th. I will show the steps as I go from here over the next couple days till finished

 

[Cogsy]

Awesome - I'll be on the edge of my seat waiting for the next instalment. I'm very keen to have a go at this sort of process but though it'd be too difficult.

 

[Naiveambition]

Here's the steps for today
View attachment ImageUploadedByModel Engines1515307215.455813.jpg
here's the part out of the rust box

Here's the boiling setup I use.
View attachment ImageUploadedByModel Engines1515307288.559607.jpg

Then the part after boiling
View attachment ImageUploadedByModel Engines1515307376.283927.jpg

And after carding.
View attachment ImageUploadedByModel Engines1515307421.524357.jpg

I should note that carding is done with a special soft wire brush or wheel not your typical wire wheel. This is about 6-7 cycles as the first few times are double coated before boiling

 

[Cogsy]

So the carding is a light buffing type procedure to remove loose surface material I take it? It's looking very nice already.

 

[WOB]

Having done a lot of rust bluing in past years, I offer some tips:
1. Just go ahead and use distilled water. It is dirt cheap at the grocery store and eliminates possible problems. It can be reused until it starts to look rust colored and then you discard it. The boiling vessel can be aluminum, stainless steel or porcelain enameled steel (cheap at the thrift store). 5-7 min. in the boil is usually sufficient. Longer does nothing.
2. Carding off the black rust after boiling can be done with 4/0 steel wool ( hard on the fingers) or fine wire brush (.005" wire or finer) Brownells offers many different shapes of carding brushes both for hand and motor power.
3. If using a 5 or 6" motor driven brush on an arbor, do not run it faster than about 300 RPM or you will wear through the blue you just created. Always card away from sharp edges and don't press hard or you will see bright metal appear. This slow speed requirement can easily be achieved by using the drill press or lathe spindle to drive the brush. Use sufficient machine protection covers and always use eye protection.
4. On plain carbon steel, 4 or 5 application cycles will usually produce a good dark blue-black. Alloy carbon steels with chrome and nickel ( like 4140) are harder to blue because they are more rust resistant to start with. You can get a decent dark gray-black, but the depth of color will not be as nice as plain carbon steel or iron. I have never tried HSS, but I predict poor results. Over 6 rusting cycles will not help on any steel and eventually the color already achieved will start to lighten. Some steel alloys will not rust blue, no matter what you do, but they are rare in the home shop.
5. If using the traditional gunsmith's rusting (mild acid) solutions, absolute cleanliness is required ( brake cleaner, rubber gloves, paper covered holders, etc). This makes solution application and carding tricky and real PIA. However, there is a solution on the market that is much more forgiving and produces excellent finishes at the same time. It is Laurel Mountain Forge Barrel Brown and Degreaser. It was developed by a chemist looking for a better way to brown muzzleloader barrels. Since browning is the same process as bluing less the boiling in water part, the solution works perfectly well for bluing. The kicker is that it also contains a detergent. This means that perfect cleanliness is no longer required. You can apply the solution to clean steel parts and also card them after boiling with clean bare hands. By eliminating the gloves and paper covered plier and vise jaws, etc., the whole process goes faster and there is less tendency for the rotating brush to grab the parts and throw them across the room. You will not appreciate the improvement until you try rust bluing for the first time. BTW, the corrosive in the solution is ferric chloride, the same stuff used to make etched copper circuit boards.
6. The rusting environment needed is warm and humid. I built a plywood cabinet that contained a hotplate/water pot and 6" fan because I didn't have another location that would work. I found that about 90F and 80% humidity promoted rapid, even rusting. The cabinet allowed me to control the conditions fairly well. YMMV.

WOB

 

[Naiveambition]

Thanx for the tips I by no way am an expert as this is my first time. So it's nice for the more educated to chime in, cause I'm still learning.
I also noticed the change in my parts after changing the rusty water out. They are now more bluish. So after this coat I will finish out with a bath in a non rust removing oil bathe for 24 hrs then wipe clean.

I did look into the laurel mtn, but I found it after I had already ordered the pilkington style solutions. I like the idea a little more for cleanliness and time vs traditional methods. But am liking the nostalgia of this one too. The weather normally in the summers the exact temp and humidity you describe everyday :wall: . It has been unusually dry, and the parts are having a slow rust on them. I may try to recoat a couple parts if my new method of changing the water every time works better.

 

[Naiveambition]

Here a pic of the finished part. Definitely happy with the last few pieces , so changing out the water helped.

 

[Cogsy]

Looks great - thanks for the tutorial, I'll look into getting the bits I need together and having a go.

 

[BucksMachinist]

Looks great Naiveambition. I have rust blued using the same procedure but I used my own mix of chemicals. I have wanted to try the Laurel Mountain product but at the time I had no income so I made my own solution. I used the following Solution:

- 2 oz 3% hydrogen peroxide

- 1/4 tsp white vinegar and sea salt to make a saturated solution then heat in microwave

Lastly I mix the hydrogen peroxide and vinegar salt mix and then reheat in the microwave.

I had to repeat the process about 8 or 9 times until I was happy with it. I did not notice the finish start to deteriorate or get lighter after the 6th time, it only got darker and darker.

To add, I also tried a HCL with either hydrogen peroxide mix or vinegar mix, I can’t remember which one it was but it did work but I never followed through with the full 7-8 repeating steps.

I have been anxious to try this method that I found on YouTube from The Cogwheel. His process seems a lot faster and he gets it done in one day. Check out the link below. It seems very promising and I might add he got really Great results!