Post rust bluing oil treatment

Rebelson

Rebelson

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Happy 2024 gentleman, ringing in the new year by firing up the tanks and doing some rust bluing on 3 rifles. Tho I've been learning this for 2 years off and on and have had beautiful results, I've never quite found a post rust blue oil treatment method that jumped out at me as better than the other. Today I want to compare some of the most popular suggestions (boiled linseed oil, beeswax, atf, kerosene) so I can nail down my new go too. Are there any others that you guys use and why do you prefer it? Thanks in advance
 
I would imagine that the poster takes the item from hot water boiling bath and dunks it directly into canola oil bath? Metal would be hot, at that point? I've never done genuine slow rust bluing - but I have done multiple time "Express Rust Bluing" - is my impression that you hang the item in a "sweat box" to get it all nice and red rust - then into boiling water tank to convert that red rust to black rust - which most of us would call "bluing". Then card off the residue, and repeat - maybe half dozen times. It will get a bit darker and more even colour, with each "turn".

I have only ever used over-night soak in clean motor oil - I was under the impression you want to "kill" the rusting process and get some oil soaked in there to protect it? I had read others use dirty motor oil - like from diesel engine oil change, etc.
 
Try atf auto trans fluid .... have a jug from last trans change

it does not gum up .... at least i have not had it gum up
you can use it as a oil / lube

I would heat the part up with a hair dryer and soak the part then let drip dry . then wipe it down later

I use it as part of ed red cleaning solution

Linseed oil will gum up
 
Potashminer said:
I would imagine that the poster takes the item from hot water boiling bath and dunks it directly into canola oil bath? Metal would be hot, at that point? I've never done genuine slow rust bluing - but I have done multiple time "Express Rust Bluing" - is my impression that you hang the item in a "sweat box" to get it all nice and red rust - then into boiling water tank to convert that red rust to black rust - which most of us would call "bluing". Then card off the residue, and repeat - maybe half dozen times. It will get a bit darker and more even colour, with each "turn".

I have only ever used over-night soak in clean motor oil - I was under the impression you want to "kill" the rusting process and get some oil soaked in there to protect it? I had read others use dirty motor oil - like from diesel engine oil change, etc.
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I tried used motor oil yesterday and its the reason I posted today, after the soak it was 2 shades lighter than when I stopped bluing and removed a good amount of hard work. I'm assuming it was leftover detergents in the oil fighting the black iron oxide, could be wrong tho. I've noticed already today that kerosene seems to turn it 2 shades darker which I'm all for.
 
I dunk parts in kerosene, then generously coat in castor oil. I let the castor oil sit for at least a day. I have been told a week is better, i cant tell the difference of extra time.

Kerosene alone will leave the metal very dry, and any lighter gun oils will need a lot of applications before the metal stops sucking it up. The castor oil is thick enough it stays put and soaks into the steel.
 
I do a fair amount of slow rust browning and bluing and basically follow the process potashminer outlined. You need to neutralize the remaining acid in the browning/bluing solution to stop the after-rusting and I have never had very good results using water, BLO, kerosene or other oils. You need to use a base and, for some products, a fairly strong base is required. Baking soda is a relatively weak base with a PH of about 8.5, and will work with some of the commercial solutions, such as Danglers. The Laurel Mountain Forge product is more aggressive and harder to kill. Household ammonia has a PH of about 11 (stronger base) and has, in the past worked well to neutralize that solution, but it is a very unpleasant product to use in a closed environment. Ordinary washing soda also has a PH of 11, and is much more user friendly. I am starting another bluing job with the LMF product tomorrow and, when the time comes, will try neutralizing with washing soda. I anticipate results similar to those achieved with ammonia. After the bluing solution has been neutralized, I wash and lube/seal the metal with RIG grease, oil or sometimes BLO - depending on the project.
 
It's great to hear so many variations ! The method I have used for many years now is to let all parts boil at least 10 minutes, making them good and hot, before the final carding. Once that is done and while the parts are still warm I coat them with a heavy coat of Break Free. Some barrels I have done over the years require a second coat after a few hours but not often does this occur. This has worked for me . Very interesting to read what others have used as their way of rust bluing.
 
I think once the metal part is fully immersed in the water - and the water is then up to a rolling boil, the metal will not get any hotter than the water is - boiling theoretically occurs about 212 degrees F (100 Celsius) with minor variations due to elevation, contaminants in the water, etc. - but temperature of that metal pretty much irrelevant how long it boils for - the temperature won't change, until you boil off the water. Is not much doubt that the process that depends on that heat, might benefit from time, though.
 
I do a lot of rust bluing. I use a homemade solution containing nitric and hydrocloric acids. On the final boiling I let it boil a bit longer. The boiling kills any further action of the acids. Baking soda is not needed, in fact I tried it once and it turned the steel grey. I wipe on a liberal coat of gun oil after final thorough carding. I have a jug of sewing machine oil I bought at a flea market I use sometimes. I would imagine any light mineral oil would do. It isn't necessary to submerge parts in a tank of oil, they don't "soak" up oil. With my process the oil turns the steel noticeably darker.
 
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smokinbarrel
Are you willing to share your formula for the rust bluing solution? Your formula containing both nitric and hydrochloric acids sounds like it might be similar to the LMF product. My supply of commercial products is getting a tad low and have not been able to find a Canadian supplier. International shipping is, apparently, not an option.

I have not experienced any color shift using baking soda or other base to neutralize the acid. I agree that prolonged boiling or steaming goes a long way toward eliminating the after-rust problem. However, that step must be omitted when browning, hence the need for a neutralizing agent.
 
smokinbarrel said:
I do a lot of rust bluing. I use a homemade solution containing nitric and hydrocloric acids. On the final boiling I let it boil a bit longer. The boiling kills any further action of the acids. Baking soda is not needed, in fact I tried it once and it turned the steel grey. I wipe on a liberal coat of gun oil after final thorough carding. I have a jug of sewing machine oil I bought at a flea market I use sometimes. I would imagine any light mineral oil would do. It isn't necessary to submerge parts in a tank of oil, they don't "soak" up oil. With my process the oil turns the steel noticeably darker.
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I tryd soak vs wipe on and noticed zero difference after 24 hours. I'm also using my own solution that I'm still working on perfecting and just as I was running out of projects worth bluing, a friend gave me 3 project guns for free saying he'd never use them. I've got the week off so back to the shop I go with a smile you could see from space. Here my results from the first 3 while the parts were warm after coming out of the tank and straight to the carding wheel YMMV

-used motor oil = removed 2 coats of bluing and lightened the part (could be used if it goes darker than intended while doing a conservation but one hell of a piss off when your aiming for jet black)

-Canola oil = 1 shade darker, smell made me hungry. Worked perfectly fine

-beeswax and olive oil 50/50 = 1-2 shades darker and I already have tons for PRB lube. It was wiped on and heated with a heat gun to soak in. Worked perfectly fine

-kerosene = 1-2 shades darker, only issue I had was after wiping on 2 heavy coats it wasn't enough and I had small areas of rust form as I believe the kerosene is a little to dry

I'll try atf today and see how it goes, any other ideas?
 
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B_noser said:
smokinbarrel
Are you willing to share your formula for the rust bluing solution? Your formula containing both nitric and hydrochloric acids sounds like it might be similar to the LMF product. My supply of commercial products is getting a tad low and have not been able to find a Canadian supplier. International shipping is, apparently, not an option.

I have not experienced any color shift using baking soda or other base to neutralize the acid. I agree that prolonged boiling or steaming goes a long way toward eliminating the after-rust problem. However, that step must be omitted when browning, hence the need for a neutralizing agent.
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I use the recipe developed by the old Neidner company in Dowagiac Mi. 2.5oz nitric, acid 2oz hyd. acid, 1oz wire nails, 30oz distilled water. That's a fairly big batch, you can half all those amounts. I put both acids in a glass jar then add the nails (outside) it is a violent reaction that gives off brown smoke. Once it calms down and nails are mostly eaten add the water. Keep in a dark glass bottle(preferably with a glass stopper). I bought a gallon jug of each of these acids many years ago, I don't know how easy it is to buy them anymore. I forget the exact % concentrations on them so you may have to experiment a bit and make adjustments with w/e is available. Book says leave it on for 3 hours, but I have run it as long as 6 without ill effects. I don't use any sort of damp box, so humidity conditions vary a bit. A note on degreasing; I wipe everything down with rubbing alcohol as a final step before applying blue and also after carding each time. Hard steel will often only need about 4 passes but typically barrels etc will take 6-8
You can overdo it, too many passes and the color will start to leave and surface begin to pit. With this solution there is no point in polishing finer than 320 grit as the solution lightly etches the metal. If done right, it is a nice matt appearance and quite durable.
A note on the nails; use soft plain steel, no galvanize or anything and smaller nails dissolve faster, rusty nails are ok too. Dump w/e is left into the final solution, they eventually disappear.
As for boiling, the book says 20min. but I usually only go about 10, the process seems to be fairly instant as soon as the parts get to temp they turn blue fast. I always let the water boil before putting parts in. On last pass I go about 20 min.
One other thing; Let parts cool before applying the next coat of bluing.
 
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Thanks smokinbarrel for that excellent explanation. Yes, the acids are very difficult to find these days. I have been trying to find some nitric to make some AF for about a year now.
 
Keeping in mind I have never done the "slow rust bluing" - it was my impression that various mixes were to create fumes - and the fumes created the red rust - which was converted to black rust. It is the "Express Rust Blue" that I have done that gets juice applied directly on to the metal. Is that mixed-up? I have a book with article by someone named John Bivins - he lists several bluing and browning recipes that he used along with his "damp box" - I do not think the solutions ever made direct contact with the metal - "Browning Solution - US Ordnance Manual 1841", "Fast Brown", "Niedner's Rust Blue", "Baker's Express Blue".
 
Potashminer said:
Keeping in mind I have never done the "slow rust bluing" - it was my impression that various mixes were to create fumes - and the fumes created the red rust - which was converted to black rust. It is the "Express Rust Blue" that I have done that gets juice applied directly on to the metal. Is that mixed-up? I have a book with article by someone named John Bivins - he lists several bluing and browning recipes that he used along with his "damp box" - I do not think the solutions ever made direct contact with the metal - "Browning Solution - US Ordnance Manual 1841", "Fast Brown", "Niedner's Rust Blue", "Baker's Express Blue".
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the Brownells 'Classic Rust Blue' is applied with a swab to the metal .. which is then allowed to oxidize ... the instructions for the use of this solution are on line and easy to find --- I wont link here because I have still dont understand the 'hot linking' rule on CGN
 
As for the application, I use a cotton ball held with an old pair of needlenose pliers. Dip one side in solution, make long strokes on metal just barely overlapping, don't rub over the same spot. Within a minute or less you will be able to see if you missed a spot. I use Q tips to get into tight areas. Don't let it puddle. It should look dry within a minute. color can vary from red rust, grey, blue and you might think you are making a mess but it all evens out when boiled.
I don't know any way of making it high gloss, generally if you want gloss a different process is in order.
I have a can of Renaissance wax I have used on wood, it's a very good wax used by restorers, museums etc. now I'm curious how it might work over bluing. I'll have to experiment.
Most of what I do is old SxS shotgun barrels so the duller matt finish is more appropriate anyway. They were originally rust blued b/c the soft soldered barrels wouldn't stand the caustic hot blue.
 
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