Bluing small parts

[Phil Coffins]

Some replica parts can have a purple color that should be blue/black. Today I decided to take care of a couple. The tools needed are a bottle of Plum Brown, propane torch, q-tips, steel wool, oil, a piece of wire, sand paper, hot plate and a tin cup full of water. The parts are sanded as needed then the wire is used to hold them. Get the water boiling in the cup and heat the parts for the browning. Coat the hot parts with Plum Brown and give them a couple of minutes to get a coat of rust then place them in the boiling water. Allow them to boil a few minutes then heat with the torch to re-coat the them with browning. Boil again then rub lightly with wet steel wool. Repeat about six times or till they look black in strong light. Oil them and set over night. Rub with a rag and you have a durable finish.
Heres two I did with another that still has that purple color from the factory. This took just over an hour to do and to my eye makes a big change.
IMG_0960 by Oliver Sudden, on Flickr

 

[FlinterNick]

I’d hot blue in sodium nitrate at 600 degrees

 

[poker]

I’d hot blue in sodium nitrate at 600 degrees

600 for sure? Some used to hot blue where we built, and I thought they always wanted 300 deg. And even then they had to add plenty water to keep the tank level up. At 600 that water must really go fast.

 

[FlinterNick]

600 degrees is the melting point. I don’t use water, just salts.

 

[SDSmlf]

600 for sure? Some used to hot blue where we built, and I thought they always wanted 300 deg. And even then they had to add plenty water to keep the tank level up. At 600 that water must really go fast.

Better check if your friends are talking Fahrenheit or Celsius, big difference. And water is basically steam over 212°F or 100°F, so it very unlikely they were adding water to keep the tank level up. You may want to stay away from these folks when they are cooking up a batch and ask you to hold their beer. Good possibly someone will get hurt.

 

[FlinterNick]

Better check if your friends are talking Fahrenheit or Celsius, big difference. And water is basically steam over 212°F or 100°F, so it very unlikely they were adding water to keep the tank level up. You may want to stay away from these folks when they are cooking up a batch and ask you to hold their beer. Good possibly someone will get hurt.

Agree, Hot Salt Bluing should never involve the use of water, adding water to a molten salts solution of nitrates will cause mini explosions and third degree burns. Not to mention the vapors could potentially blind you.

 

[poker]

You boys best hide under your beds. The boogeyman might getcha!

 

[poker]

Agree, Hot Salt Bluing should never involve the use of water, adding water to a molten salts solution of nitrates will cause mini explosions and third degree burns. Not to mention the vapors could potentially blind you.

Youre showing confusion or is it ignorance? What do you think the salts are in solution with? Its water. And the boiling point of that water with the salt in it is right around 300 degrees. Get yourselves some experience before making wild claims.

 

[FlinterNick]

Youre showing confusion or is it ignorance? What do you think the salts are in solution with? Its water. And the boiling point of that water with the salt in it is right around 300 degrees. Get yourselves some experience before making wild claims.

I’m not sure what salts you’re referring too, but the salts I use; Sodium Nitrate or Nitre Salts (sodium nitrate mixed with potassium nitrate) by Browning do not melt or dissolve at 300 degrees they melt at 600-700 degrees,they will still be a solid state and the instructions do not say mix with water it says exactly the opposite, and I’ve seen the mistake of mixing water in nitre salts, Please refer below.

 

[FlinterNick]

Youre showing confusion or is it ignorance? What do you think the salts are in solution with? Its water. And the boiling point of that water with the salt in it is right around 300 degrees. Get yourselves some experience before making wild claims.

Here’s a video for you, https://www.google.com/url?sa=t&rct...=-vF3zKiUIkY&usg=AOvVaw2ibTEntaSKukBB_YD9X697

 

[SDSmlf]

Youre showing confusion or is it ignorance? What do you think the salts are in solution with? Its water. And the boiling point of that water with the salt in it is right around 300 degrees. Get yourselves some experience before making wild claims.

I am seeing confusion and ignorance. One does not use boiling saltwater to blue the steel, rather one uses a salt heated to the point where it turns into a liquid. This occurs well above the temperature that water boils.

Could you please tell us about the 300° water and salt process you use to blue steel? It would be interesting to hear the details.

As far as my hands on experience for my wild claims, during my toolmaker apprenticeship I spent time heat treating various metals in salt baths. Different salts and at even higher temperatures than we are talking about here. Any water or oil on a piece metal being placed in the salt was dangerous situation. If you would like to see a similar reaction, dump some water in cooking oil that has been heated to 400° F or so and tell us what occurs.

 

[user 34300]

I tend to heat such parts to the point they just begin to glow dull red in shop light then quench in canola oil. That gives black. I do not currently have any sodium nitrate to melt, I have in the past. That works too and can give a bright indigo blue.

 

[FlinterNick]

I tend to heat such parts to the point they just begin to glow dull red in shop light then quench in canola oil. That gives black. I do not currently have any sodium nitrate to melt, I have in the past. That works too and can give a bright indigo blue.

I use a mixture of sodium nitrate, potassium nitrate and caustic salt beads to temper steel parts and springs.

I dip the parts in at 580 / 600 for a deep blue temper at 700 the bluing color is more of a grayish blue.

It works great on springs.

I had a friend who was a watch maker and he used salts to blue watch springs and clock hands.

 

[Phil Coffins]

Calm down boys! The 300 degrees noted is for caustic salt bluing as used commonly by gunsmiths. You do add water to it. The 600 degree stuff is nidner blueing and often used by smiths.

 

[FlinterNick]

Calm down boys! The 300 degrees noted is for caustic salt bluing as used commonly by gunsmiths. You do add water to it. The 600 degree stuff is nidner blueing and often used by smiths.

I know of the dissolved bath salt bath method, and have always been told its a much more inferior technique to nitre’ bluing. Nitre bluing is actually a form of steel tempering, as to where the later is more a staining technique.

I almost always using molten nitre salts to temper springs, blue screws, sights, and temper back some internal parts like bridles.

 

[SDSmlf]

I know of the dissolved bath salt bath method, and have always been told its a much more inferior technique to nitre’ bluing. Nitre bluing is actually a form of steel tempering, as to where the later is more a staining technique.

I almost always using molten nitre salts to temper springs, blue screws, sights, and temper back some internal parts like bridles.

I wouldn’t consider a dissolved salt bath at 300°F a hot bluing method, but it does use salt and water well above water’s boiling point, so I stand corrected. Guessing whether using this method or the higher temperature (600°F) stump killer process it is not something to do on the kitchen stove unless you live alone.

 

[The Crisco Kid]

Back to the purple color in the OP, I've rust blued purple parts from a well known manufacturer of unmentionables and they came out a nice blue/black.

 

[SlidePicker]

Hot salt bath bluing is the way modern commercial unmentionables are blued. Solutes raise the boiling point of water, and the lye and nitrate do bring the boiling point close to 300F. I seem to recall around 270, but I'm not looking it up right now. Water is added when needed in the form of ice cubes, to prevent explosions splattering dangerous stuff. Rust bluing is much more practical for most of us doing hobby work at home. Before WWII, most all bluing was done this way. And if you ever have unwanted rust on a firearm, for heaven's sake don't scrub it with an abrasive! Boil it first. The rust will rub off with a cloth, even a paper towel, though I like to burnish it with wood. Pits, if any, will remain, but all of the rusty surface is now rust blued and looks far better than you can achieve with any abrasive.

 

[J2shortt]

Closest thing to any of this I've done is the canola oil thing, bit it was old used motor oil... But my version of hot blueing, is me using Birchwood Casey's Perma Blue, brushed on with an old paint brush, while in my garage in the middle of the summer with no air conditioning. It's safe to say my blueing jobs come out looking like ****. lol

I can use a sharpie to get that deep dark luscious finish. Just don't ever try to clean that gun part.

All jokes aside, I do find it interesting to hear about the few different ways the members have done blueing in the past. I have to say the gunsmithing finish aspect of building is by far the most interesting to me. You can make a hunk of junk look like it works well just by applying a really nice finish.

 

[Phil Coffins]

The durably of bluing is rust blue then caustic salt blue then charcoal bluing then nidner blue with the least being heat blued. I’ve done each and each has its purpose. We can debate the finer points and methods but many a book has been written on how to do them and the value of each. I suggest if a fellow has interest he gets to reading then actually do the work.