# Bluing steel part.



## Pigi_102

Hi all.
 Before starting my first engine build I needed a boring head, and decided to make one as per http://www.deansphotographica.com/machining/projects/mill/boring/boring.html

After finishing, to protect her from rusting I decided to hot blue her. Here the procedure that I hope may help someone.
I took a chunk of brass to get some swarf, mounted on the lathe and faced it "heavy" to get sligthly big swarf.
After getting enough swarf I took a metal cup and filled with parts to blue and brass swarf.
I put the cup on kitches fires until got the blu I want.
When reaching the blue I have quenched in unused motor oil.

The result is really nice, at least in my opinion.

The brass swarf are needed to get an even heating to the parts. Is mandatory to very good clean the parts as also a little point of oil or grease could end in a parte not blued ( don't ask me how I know it &#65532; ) 

Hope this help someone.

Pigi


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## petertha

Neat. What is your temperature & soak time recipe? And what alloy is the steel head itself?


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## Pigi_102

I haven't a way to measure the temperature, but according to this image attached it should be somewhere around 285/310° C

I kept the part in the cup until I've seen the blue I was looking for on the exposed side of the part.

It took something around 15/20 minutes to get there.

The material is leaded-steel alloy ( I think you call it free cutting steel ).

Pigi


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## Cogsy

Great job. I'm going to file that away for future use for sure. Thanks.


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## Wizard69

Are you using some sort of glueing solution?   I guess I'm not sure how you lock in the blue.


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## Longboy

I have been flame coloring my rocker arms on a couple of engines with a propane torch. A little tricky on small parts as the hue can change rapidly as the temps go up in a mater of a few seconds.


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## Pigi_102

Wizard69 said:


> Are you using some sort of glueing solution?   I guess I'm not sure how you lock in the blue.



No glueing solution, only what I told.
Take the pieces, put in brass, heat on fire till the blue, quench in oil, clean with towel or paper.

Pigi


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## mcostello

Check out "Clickspring" on Youtube He does clocks and parts.


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## Pigi_102

That's exactly my ispiration !

Pay attention to clickspring channel, BTW, it give dependency  

Pigi


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## Wizard69

Pigi_102 said:


> No glueing solution, only what I told.
> 
> Take the pieces, put in brass, heat on fire till the blue, quench in oil, clean with towel or paper.
> 
> 
> 
> Pigi




Sorry, that was suppose to be blueing solution.  Auto correct did me in - again.

This has me wondering if this is true bluing because normally you think of caustic baths to blue things.


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## 10K Pete

This is called.......     Heat Blue.!!

Used in watches, clocks and guns for a long time. Works especially well
with polished parts.

Not traditionally used for large parts. Small parts and screws. 

Pete


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## ruzzie

I tried out a blackening kit from www.janekits.com.au


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## Pigi_102

ruzzie said:


> I tried out a blackening kit from www.janekits.com.au



That looks nice ! 
In any case is a chemical solution, while my way ( well, the way I used, not my way ) does not need anymore than heat.


Pigi


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## Swifty

I've been using a chemical blacking kit for years, works very well and the chemicals last for years.

Paul.


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## Scribealine

A very old method indeed!
  Used mainly in watch making in the late 1700's, to blue watch hands and screw heads,
the finish can be enhanced with a fine polish prior to heating, the brass swarf method is always used in horology.
Good to see it.
Cheers


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## bmac2

Scribealine.  You got me. I had to go look that one up.
ho·rol·o·gy
Noun
The study and measurement of time.
The art of making clocks and watches.


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## petertha

What is the significance of the brass chips/shavings when torch/heat bluing steel? ie. is there something special about that particular alloy over other choices? Or is brass just what's usually found in a watchmakers chip tray under the lathe?


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## Buchanan

The brass serves to conduct  and spread the heat in a uniform way, you can spoon or move  the brass  around on the part to heat one part more than the other to obtain an even color. Clean sand  also works.  The emphasis is on clean. Any oil or grease will give color variations. A very fine sand paper finish(2500) grit gives a better blue than a mop polish. The type of steel also affects the color  Chrome or nickel does not help things and stainless steel is usually hopeless. It is simple to try and if you are not happy with the results it is not to difficult the remove the blue and try again.  Every time this happens the polish also improves! The trick is to keep every thing clean and heat slowly. The atmosphere seems to have some effect on the color as well.  The old folk always said to use a charcoal fire for the best results. A hot air gun also works as a heat source but I have not found the results to be quite a good as a flame. 
An electric muffle also works, you can take the temperature up a few degrees at a time to get the color you like, especially when the part has thick and thin sections. 

Buchanan


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## petertha

Thanks Buchanan. That's kind of why I was asking the question. The blueing temp looks to be just outside the range of my little re-purposed engine bearing removal oven (formerly known as our kitchen mini toaster oven). But assuming you could dial in a specific temp & let it soak there (maybe a conventional heat treating oven in low temp mode) presumably this would be more consistent vs. a torch...  would underlying shavings or sand or whatever make any difference if for example you could jut suspend the part on a wire so it was hanging with the exact same atmosphere all around it & no 'bed' contact of any kind?

ps - I've been lurking on your website just fascinated with the clock constructions. Incredible work.


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## Buchanan

Pertha. yes, I mostly do just that, hang parts (clock) on a thin wire in an oven, The temperatures are obtainable in most cooking devises. Pigi's color chart back a few posts is correct. Screws , I use a block of brass with clearance holes for the thread and heat from below with a small butane torch. Thank you for the compliments . You can see more at www.buchananclocks.com. 

Buchanan


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## Nick Hulme

(Heat) Oxide colouring is great for delicate parts but doesn't offer the increased wear resistance and oil retention of gun blues making it less suitable for larger, regularly used and handled parts.


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## Buchanan

Nick    

Can one obtain an electric blue  or fairly light blue with Gun blue? 
Most Gun Blue that I have used over the years gives more of a black blue. 
also the blue that I am looking for must be very even, not mottled at all.
any comments would be appreciated. 
Buchanan


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## petertha

I cant speak for lighter shading aspect but the Clickspring series shows his method & some nice results in terms of evenness & lustre.
http://www.clickspringprojects.com/


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## Nick Hulme

Buchanan said:


> Nick
> 
> Can one obtain an electric blue  or fairly light blue with Gun blue?
> Most Gun Blue that I have used over the years gives more of a black blue.
> also the blue that I am looking for must be very even, not mottled at all.
> any comments would be appreciated.
> Buchanan



My point is simply that (Heat) Oxide colouring is great for delicate parts like clock screws which are not often handled but it doesn't offer the increased wear resistance and oil retention of gun blues making it less suitable for larger, regularly used and handled parts, if you used it on a trigger for instance it would begin to wear off with relatively little use. 

Unless you recommend (Heat) Oxide blues for firearms and items subject to wear? 
Any comments would be appreciated ;-) 

 - Nick


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## Buchanan

Nick. 

I am asking from the clock makers point of view. If gun blue gives oil retention and harder wear  and I can obtain the color I am looking for, then I want to use it on clocks. Clock oxide blue would not work on guns as you say. Thjanks. 

Buchanan


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## Toolguy

Nitre Blue for guns gives a similar iridescent bright blue as the heating. It is only for show pieces normally, as it doesn't hold up to a lot of handling as well as a normal hot blue.


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## Buchanan

Thank you I will give it a try. how do you stop it rusting?


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## Toolguy

I like to rinse well with hot water, oil and let sit for a day, then wipe off oil and wax with car or furniture wax.


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## Buchanan

What oil do you use. I can get a good blue but when I oil it, the blue goes dull. I use engine oil.Thanks for the feedback.


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## Toolguy

I usually use a vegetable based cooking oil for that. Olive, sunflower, canola, etc. The motor oil may have chemicals that attack the blue. Or skip the oil & go to wax.


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## Wizard69

Buchanan said:


> What oil do you use. I can get a good blue but when I oil it, the blue goes dull. I use engine oil.Thanks for the feedback.



I did do some steel blackening and used a gun treatment to provide additional protection.   Probably BreakFree or something similar.   Got the materials form a sporting goods store if I remember correctly.    This certainly isn't blueing in the Blue sense.

These people sell a kit: http://www.caswellplating.com/metal-antiquing/black-oxide-kits.html that seems to meet the needs of model engineers and the like.   I suspect it is similar to what I used on a spacer block made for a tool post.   It has held up well so far.    Interestingly Caswell calls the coating a sealant.   I have some other stuff I need to treat so Caswell may be getting an order from me soon.   In any event don't have much experience beyond a couple of pieces and there I can't remember where I got the materials.   I believe they where Birchwood-Casey.

Side note to myself, I really need to start writing this stuff down, old age is not kind to memory.


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## scroc

I have been using a chemical blueing agent from :Brownells:http://www.brownells.com/
They have provided blueing solutions to metal workers for many years.
Rather than deal with heated solutions I use their cold blues labeled "Oxpho-Blue" and "Dicropan T-4", they are both very wear resistant and attractive as well as being simple to use. 
Results through out the years have always been great and well accepted by fussy folks.
scroc


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## Nick Hulme

Hot blueing chemically changes the surface layer of the steel to the same composition as haematite, it's harder than the steel and is porous allowing it to absorb and hold oil. 
Cold processes do not produce a coating of the same composition or wear resistance.


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## Wizard69

Nick Hulme said:


> Hot blueing chemically changes the surface layer of the steel to the same composition as haematite, it's harder than the steel and is porous allowing it to absorb and hold oil.
> 
> Cold processes do not produce a coating of the same composition or wear resistance.




Which brings up some interesting questions:

1.  Does anybody know of a good web site that covers hot bluing processes from the hobbyist level?   

2.   Same question for color case hardening especially as an alternative to bluing.    

3.   Has any one tried the Cerakote type ceramic finishes for use on shop tools?    I see potential here as an alternative to bluing but have no experience with respect to durability when handled in this environment.  

I ask because i have some tooling bits and pieces id like to blue and was going to go with a kit from Caswell.     In the back of my mind though there is this concern that the cold processes aren't as durable as the processes they replace.   

In a nut shell looking for a durable but not too complicated way to finish steel parts.   Especially parts that will be handled a lot.


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## enfieldbullet

Are you trying to blue tooling? if so cold bluing is a good option.

Sure, it isn`t very durable but its good enough for tooling and seems to be what manufacturers use in most parts. Plus, if you keep your tools oiled they shouldn`t rust. Parts that are handled a lot will always develop some patina from handling, but the patina is a good thing as it will keep the part from rusting badly(kind of like rust bluing)

Rust bluing is an alternative...but it takes a LOT of work, which in my opinion is uncalled for in tooling.

hot bluing consists basically of using molten lye (sodium hydroxide) to dip the part in. that bath runs at around 300 degrees celsius.(which could ruin the hardening of parts)


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## nel2lar

I might be wrong but the blue that Chris (Clickspring) get on his parts is just surface and very easily removed. Just too much handling will start to thinnen the blue surface. One of his vidoes show it well, the video of the click spring. If you watch the click, you will see the surface that rubs on the gear looses its blue quickly.


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## Pigi_102

I must say that it's passed almost 8 months since I blued my part, and she is a boring head.
I don't use her too much, but in this 8 months I've used it quite a bit.

The only places where I'm having some problems are in areas where she was not completely clean before the hot bath in brass, and started to develop some rust. 
All the other blued part are still there holding their wonderful blue, and so far I don't see any important scratch.

A boring head is somewhat prone to get scratches for all the chips that reach her during the job. So I'm satisfied.

Pigi


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## Stieglitz

Hi Pigi,
         Very helpful ,it will be useful on  future projects.Thanks for sharing.
Allen.


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## 10thumbs

Having a degree in gunsmithing, I have used a lot of products for blueing, but the one I keep coming back to for ease of use and durability is Mark Lee Express Blue, available at Brownells.
It is applied with a heat source until chocolate brown and activated by a five minute boiling water bath. Then carded with steel wool or a carding wheel, then waxed while hot. That's it. 
 It can be a lot of work on gun parts since there is usually so many, but for an odd part here and there, its hard to beat, and I've pretty well quit using hot caustic salts. It comes out a satin black,  has good handling resistance, and won't hurt heat treating. 
  So if you aren't looking for an actual blue color, or a glossy shine, its good stuff.


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