Rain water vs distilled or deionized water for rust bluing?

[robroy]

I'm setting up a shop and hot bluing is out of the question for a number of reasons. I've got a PVC pipe tank to hold hot water for rust bluing. Buying distilled/deionized water for every job seems a bit expensive and dumping rainwater down the drain after every job seems wasteful to me as well. So really 3 questions:

1. Does rainwater do the job as well as distilled?
2. Can the water be reused for the next job?
3. Is there a test, such as pH to tell when the water needs to be changed?

Opinions and guesses welcome. Please let me know when you're guessing, opining, and when you've got some hands on with this.

Thanks in advance.

[calaloo]

I have an open top stainless steel tray in which I do rust bluing. I use distilled water from Walmart and save it to be reused. I always have to top up with a couple of gallons at each bluing session--- less than $2.00. And then there is the last little bit that is muddy with sludge that I discard. I can't see why rain water would not work. My well water would probably work but I live in limestone country so its distilled for me.
Calaloo

[357maximum]

You can bring a truck to my house and shovel up all the free rainwater you want for free......cannot promise it will not melt on your way home though. On the south edge of my place I have a drift that is about 30 foot wide, about 9 feet deep, and about 1/4 mile long...should get you plenty of "rainwater".

[oldred]

I have heard that rain water success varies from area to area depending on the amount and content of the pollution, it makes sense and it's a fact that rain water is seldom clean even if you live in a pristine area because weather fronts can come from far away. A source of water that I use is from our dehumidifiers, it's free, plentiful and has worked perfectly every time but then why shouldn't it, it's from water vapor and vapor can't hold pollutants. Rain water can stain most anything left outside and often will etch Aluminum, that along with the other well known problems caused by acid rain tends to make me agree with the idea that rain water could be a poor choice, again rainwater is a long way from being pure!

[robroy]

Might be a bit expensive to get a dump tanker up to Michi-Braska from Beaver Co PA. Got a picture of my brother and me on top of a drift in the lee of Grandpa's wind brake. We're looking into the wind over top of the Russian olives that were on the west edge of the yard. I'm guessing 20 feet above the ground. That was a very snowy winter on the Montana prairie.

Replenishing rather than replacing sounds like a winner. I take it the bluing solution doesn't signifficantly contaminate the water. That might depend on the solution used. I haven't decided which one to use yet.

[Murphy]

Interesting question.

I operated a water treatment facility for 15 years. We ran daily tests for pH levels, maganese, iron...etc. All of the above can effect the outcome of what is attempting to be accomplished. Too much, or too little of any of them will change the properties of your bluing batch.

I once caught a good size sample of rain water during work just to see the difference, between it and the surface water we were treating. It's different for certain. Staying with distilled or deionized water will give you a more consistant outcome.

And yes, you can buy a pH testing kit very reasonable. It would be much easier if it were during summer months. As most swimming pool supply outfits carry pH testing kits, as does Wally World.

Murphy

[aspangler]

In my experience you are better off to use distilled and change it EVERY time. I use Art's Belgium Blue and it works great if you don't reuse the water. You will get contaminates in the water every time you blue and you won't get consistent results unless you change water after each session. That is what I have found and also what my gunsmith mentor has told me from his considerable experience.

[Reverend Recoil]

Air conditioner condensate is distilled water and works great for rust blueing. It is produced for free on any hot, humid summer day.

[oldred]

Air conditioner condensate is distilled water and works great for rust blueing. It is produced for free on any hot, humid summer day.

That's the same as what is collected in a dehumidifier but the dehumidifier will make a LOT more water and do it a lot faster, still AC water can be collected and it certainly does work.

[seaboltm]

I rust blue a lot, and I use tap water. The movement of electrons during the boiling process is essential to convert the red iron oxide to black iron oxide, also called magnetite and lodestone. A/C condensate is far from pure as there will be quite a bit of aluminum oxides in it, which helps electrons move during the boiling process, so yes, A/C condensate will work, but so will tap water.

Another thing to keep in mind is the magnetite is formed from red iron oxide in the presence of heat, no oxygen, and a medium to allow electron transfer. I boil the water for a few minutes before putting the rusted piece in the water. The boiling will drive the dissolved gasses out of the water. You can prove this to yourself easily enough. Boil some water, let it cool, and then put a goldfish in it. That goldfish won't be alive for long as the dissolved oxygen was driven out of the water by boiling. Yes, the water will regain oxygen over time, but not in time for mr. goldfish.

I change the water after the first boiling only. There will be visible red contamination after the first boiling that does not appear much in the subsequent boilings. But I am using a stainless steel tank, so I don't get a lot of extra rust and crud that an iron tank would give you. If you are using a tank that is not stainless, change the water after each cycle.

I generally do 6 cycles of rust. That is usually enough. I did a very old J.P. Sauer sxs shotgun barrel for a buddy and that old steel took about 12 cycles, but he was adamant about not removing metal before bluing. I generally sand blast and then buff. You can use glass beads, and I have, but I prefer sand followed by a 320 grit buff on a loose wheel. There is no need to go for a high polish because the acid and rusting process will leave the metal slightly matte at the end of the process.

As to acid, Brownell's works great and is much cheaper than Pilkington's.

As to PH, don't overthink this. It is not that difficult. I have actually put a few drops of acid in my water to get it more acidic! Remember, this process is not like caustic salt bluing. The chemical process here is quite different. Metallurgy factors such as steel content and heat treatment will have much more impact on your rust bluing that the water, and you can't do anything about Metallurgy.

[robroy]

Thanks again for the info. some interesting opinions.

The one rust blue job I did was with Belgian Blue on a sxs 12 ga. I got good color and fairly quickly. IIRC I used tap water. I need to find out if the water available at the shop is well water or city water.

[seaboltm]

Thanks again for the info. some interesting opinions.

The one rust blue job I did was with Belgian Blue on a sxs 12 ga. I got good color and fairly quickly. IIRC I used tap water. I need to find out if the water available at the shop is well water or city water.

I doubt well water will matter versus tap water. The thing is we are looking for is free ions in the water that can help electron transport. Well water will likely be alkaline, but that's ok. Alkaline water moves electrons too! I should say I am not a gunsmith, but I am a physicist, and I did my dissertation concerning the surface physics of metals many years ago, and surface physics is precisely what bluing is.

[robroy]

So seaboltm, how come black oxide doesn't change the dimension of steel but red oxide does. If I have to do differential equations to get it don't even bother.

[Duckiller]

Rain water is not that pure. Remember every drop of rain forms around a particle of dirt. I have done no blueing but there are filters that will clean up water. Figure out what you don't want in your water then get a filter that will at least take most of the bad stuff out.

[seaboltm]

So seaboltm, how come black oxide doesn't change the dimension of steel but red oxide does. If I have to do differential equations to get it don't even bother.

Have you measured that? Because I have not. But I do know you don't get to black oxide without having red oxide first. So, from that logic, if red oxide changes the dimensions, so does black oxide. No differential equations needed, and I doubt we will need Lagrange Undetermined Multipliers to get closer to a solution. Red oxide probably has a larger crystalline structure than black oxide, hence the dimension change, but I am just guessing.

[John Boy]

That's the same as what is collected in a dehumidifier but the dehumidifier will make a LOT more water and do it a lot faster

Just clean the bacteria out of the tank and it can't get any better for bluing

[robroy]

I say the dimensions don't change because I was told that by my bluing instructor. Everything worked and fit after hot tank bluing as it did before, so I had no reason to check. I guess the more pertinent question is what do you do to protecr the internals from corrosion. I've heard of coating the slots and such on the inside of an action with laquer to protect them and then removing the coating with solvent. I wonder if this is really necessary if they don't get treated with the bluing solution. It would be rather hard to card the inside of a lever gun or a box lock for that matter.

[seaboltm]

I say the dimensions don't change because I was told that by my bluing instructor. Everything worked and fit after hot tank bluing as it did before, so I had no reason to check. I guess the more pertinent question is what do you do to protecr the internals from corrosion. I've heard of coating the slots and such on the inside of an action with laquer to protect them and then removing the coating with solvent. I wonder if this is really necessary if they don't get treated with the bluing solution. It would be rather hard to card the inside of a lever gun or a box lock for that matter.

As to internals, you will find that the metal that has not been exposed to acid will not corrode much at all, if any. I use a hand held carding brush for internals, and sometimes 0000 steel wool wrapped around a nylon cleaning brush and powered by a drill. Keep water out of the barrel using wooden plugs. Rust bluing is labor intensive, which is one reason no one but hobbyist and custom gun makers really do it much anymore. The industry switched to caustic salts for a reason: they are much easier and faster. I have done caustic salt bluing, rust bluing, and parkerizing. Now I only parkerize and rust blue.

[robroy]

I agree much faster with good results. We just don't have the room.

[rattletrap1970]

Quick question about the boiling process.

Every gun I have ever blued has been rust blued. I prefer Mark Lee Express blue. I have used Pilkington's, but I find Mark Lee is more reactive (Faster). Generally I do polish the metal with an 3M bonded 8S EXL Fine wheel. I find that Rust Bluing will dull the finish as it is caustic, but, only so much. So the shinier you start, the shinier you end up. I find I have better results the more used the water is, that is, the more times I boil parts in it. Finishing, I heat the parts till they are quite hot with a torch and drop them in high sulfur cutting oil. I repeat this a couple times. Then wipe them off well and lightly oil with that Lanolin based spray. I have achieve a shiny black that is comparable with decent Hot Salt bluing (depending on the alloy of course). But I'm always looking to improve.

Now the question: As far as deepening the black (if that is possible) is there anything that can be added to the boiling water to make the process darker? i.e. Higher Ph, Lower Ph, salts (NaCl or otherwise), buffers, borax, anything?

Thanks.