Humidity and Temp for slow bluing ??

[Theditchman]

I am thinking of building a humidity cabinet..Does anyone know what optimum levels are?

[NyFirefighter357]

https://www.trackofthewolf.com/pdfs/...structions.pdf

Pages 6- 7 https://www.riflemagazine.com/magazi...i36partial.pdf

[LAGS]

I have no idea on the Humidity level.
Since I was single for the past 18 years , I just hung my parts in the second bathroom , turned on the shower and let the room steam up.
Then every couple of hours I would steam up the room again.
But the class I took on Slow Rust Bluing , they had a metal cabinet that they put a metal bowl on a hot plate and just left it overnight.
The water never boiled out , or really created steam.
But in climates where it is Humid and not Dry like Arizona there should be enough humidity in the air.
All you have to do is add a little heat like from an electric hot plate or a bright light in an enclosed space.
The metal cabinet we used was a Metal Closet they bought at Wall Mart.
One caution.
Do not create too much steam that water condenses on the metal.
That will make spots or streaks.
I got one barrel that I have to refinish because I forgot to turn the shower off for four hours and it was hanging in a cloud of steam for hours.
That reminds me.
Now that I am married again , and moved into a new house , I better make myself a steaming cabinet for the new shop.

[waksupi]

I'm currently bluing a barrel. I just set it outside, and am having excellent results. In dry weather, it just takes an extra day to get the oxidation I want. My strongest caution is to not let the metal get actually rusty, if you want a good high sheen finish. You may not think it is doing anything with just a small amount of oxidation, until you put it through the heat.
I updated my steamer a bit, I had a piece of heavy wall 8" pvc to use, as the lighter pvc I had been using would soften enough to tip over at times. I wait until the water hits a good rolling boil, then set the pvc pipe directly in the pot so it doesn't over heat. Steam for 20 minutes, remove barrel immediately using welding gloves, and wipe any moisture beads from the barrel. This will prevent a lot of the spotting people fight with. Then you can let the metal cool and buff it out. Things like screws just get dropped into the boiling pot. Or, you can tie them to a string, make a bag from an old sock, or screen so they hang directly in the steam.
If I was going to do a lot of bluing, I would get a couple sections of stove pipe, being lighter to handle.
You could also use the pipe for humidity, just put a bit of water in the pot, set the tube in, and let nature take it's part. I use a piece of metal or wood with a couple small holes drilled in it for some wire hooks to hang barrel and parts from.
If you use the steam method, 20 minutes is fine. The boiling parts need 25 minutes, as the steam is so much hotter than the boiling water. Don't start counting time until you see steam coming out the top.

[LAGS]

To me, Steam bluing is fine.
But that is not Slow Rust Bluing.
It is like Hot Bluing Vs Cold Bluing.
Slow rust seems to last longer.
But Steam bluing does get the job DONE.
My guns , get Slow Rusted.
Flip guns get steam blued

[BPJONES]

I have slow rust blued about 6 sets of vintage double barrel shotgun barrels. I use a wooden surplus ammo crate that has a door/lid on it. I just hang the barrels in it and I hang a damp rag on each side of the barrels. It seems to work fine and it is not high humidity where I am, particularly during the winter which is when I usually rust blue. It's sure not high tech but it works.

[waksupi]

To me, Steam bluing is fine.
But that is not Slow Rust Bluing.
It is like Hot Bluing Vs Cold Bluing.
Slow rust seems to last longer.
But Steam bluing does get the job DONE.
My guns , get Slow Rusted.
Flip guns get steam blued

I am doing slow rust. Steaming is just a substitute for boiling out, with less equipment.

[LAGS]

That is true
Steaming the parts to convert the red oxidation to blue or black is way faster and cheaper.
But I have noticed that the finish converts more evenly if is Boiled properly.
The submersion in the water while boiling eliminates all the Oxygen and does make the finish a little deeper And more durable.
But it is your choice and I use both methods.
It just depends on the rifle I am doing and if is a customer's gun.

[Chill Wills]

I have no idea on the Humidity level.
One caution.
Do not create too much steam that water condenses on the metal.
That will make spots or streaks.
I got one barrel that I have to refinish because I forgot to turn the shower off for four hours and it was hanging in a cloud of steam for hours.

Interesting.
I got a lot of help on here especially from the replies LAGS took the time to write detailed replies.
I am not and old vet of slow rust but have done start to finish about 4 projects worth.
I have not tried all the ways so I really have no business offering advice.


I will cut to it on what little I have that works for me. I live at altitude. Water boils at 196 F to maybe 198F.
Conversion to black oxide happens with in a few degrees as the water comes to a boil. I know as I was interested and tracked it with the kitchen probe thermometer. I know little to nothing about the conversion with steam other than the parts sticking out above the water and my part was getting splashed so that really does not count, plus I rotated it too. Boiling water to black oxide conversation at my elevation happens in the lower to mid 190's F.

It makes me wonder if there is an elevation at which water boils at too low a temperature to get a conversion?

Because I am set with this boil system and it is very easy - easy as falling off a log - I will stick with it and not try any of the other steam methods. Just more stuff to buy, build and store.

The first project, a barrel, I got too aggressive not knowing what to expect and put a pan of very steamy water in the bottom of the rust box and the next morning I had very red rust covering the barrel. Condensation in the form of water drops condensed on the metal. This caused spots that I was never able to get out with repeated cycles. I will be redoing this barrel.

Getting parts to rust in the dry Rocky Mountains air - I had a few interesting cycles of too much rust and too little rust and found out that the barrel box I built out of some 1/2" scrap OSB board, a water filled spray bottle and an old wash cloth was about right. I would wet the wash cloth and hang is inside, plus spray the inside of the wood door with water and 12 hours later, and that is not written in stone, you boil off the parts or barrel and then card. Easy! Four to eight cycles and done.

[LAGS]

I believe that the Oxygen releasing from the water is what does the conversion.
That would be at whatever temperature that the water Boils.
But in the high altitude , your range of temperature is much closer and like you said cooler.
But Steam is effected the same way.
Steam at high altitude is really not 212 degrees.
I have never tried Bluing at high altitudes , and we all have to make adjustments for where we live as well as the weather outside.
But from my experience cooking food at high altitudes was that things Cool off quicker in the high altatudes.
Hope this helps.

[LAGS]

One other thing I have noticed.
Everyone I know that does Steam Conversion , uses Tap water to make their steam.
Tap water can contain Minerals that can promote rust starting again.
Depending on where you live and your water.
Also , hanging my parts in a Steamy bathroom to rust is more prone to spotting because if there is too much steam , that water drops when it condenses contains more minerals.
I do get better conversion if I use Distilled water.
But if you are only Raising the humidity to promote rust , the chance of a lot of minerals being present is less.

[Chill Wills]

I think there is no reason to be concerned about the impurities in steam, not water, but in steam. When liquid water converts to vapor, it does not contain any residual chemistry.

Water, used with the boil method = yes. Used distilled. It is cheap and easy.
Steam = no problem.

[charlie b]

A gunsmith friend out here used to do the hot blue with boiling water (distilled, our water is hard as a rock). He worked on it a bit until he managed to recreate the old Colt blue. Boiling was one of the keys to it. He roughened up the inside of the tank and controlled the heat applied to get smaller bubbles and that made a difference. We are at 4500ft elevation so the temp is a little lower too. I am not sure but I think he added something to the water to up the boiling temp as well. Something about 220deg but that is just a wisp of a memory so could be completely different.

[waksupi]

That is true
Steaming the parts to convert the red oxidation to blue or black is way faster and cheaper.
But I have noticed that the finish converts more evenly if is Boiled properly.
The submersion in the water while boiling eliminates all the Oxygen and does make the finish a little deeper And more durable.
But it is your choice and I use both methods.
It just depends on the rifle I am doing and if is a customer's gun.

If I DO get any spotting, the Brownell's stainless buffing wheel blends them together nicely, making imperfections disappear.

[waksupi]

I think there is no reason to be concerned about the impurities in steam, not water, but in steam. When liquid water converts to vapor, it does not contain any residual chemistry.

Water, used with the boil method = yes. Used distilled. It is cheap and easy.
Steam = no problem.

Steam is in effect distilled water.