Author Topic: Bluing steel  (Read 5478 times)

Offline Bangkok Mick

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Bluing steel
« on: October 02, 2014, 04:03:05 AM »
Has anyone had any experience bluing steel for aesthetic effect and anti-corrosion like a gun smith would do.

I produced a small steel model shotgun a while ago and am currently playing with a miniature crossbow (5 to 6 long) also of steel and am considering an appropriate but reasonable simple finish for it.

Any advice greatly appreciated.

Cheers Mick

Offline Eugene

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Re: Bluing steel
« Reply #1 on: October 02, 2014, 07:54:30 AM »
Mick,

If by bluing you mean blacking (confusing terminology what?) you can do that in a couple of ways; hot caustic / nitrate / nitrite mixes available as "steel blacking salts" or rust bluing. The hot caustic method is simple and effective but you must have personal safety right in the front of your mind; 700 g/l caustic soda at 140 deg C isn't user friendly. The rusting process is a bit tedious and time consuming but safe, and gives a really nice finish when done right. There is also a cold bluing process that is available commercially (at some expense) but I've never used it so can't comment. The materials for rust bluing are easily obtained (well they are in Wales, not sure about Thailand!) from Brownells in the US and are cheap enough.

For bluing as in the colour blue, for small steel parts that are not critically hardened and tempered (springs, receivers and such) you can use the same stuff that clockmakers employ to blue clock hands. This gives a really nice bright blue to things like triggers. It isn't particularly hard wearing; I did the triggers on my SxS and they are looking tired after a couple of busy seasons, however it does make a really nice job on the heads of screws and pins that aren't subject to much wear. It's available commercially as in ...http://www.johnwardle.co.uk/250g-bluing-salts-15-p.asp A skilled man can do bright bluing with a gas torch, but I always muff it.

The standard work is "Firearm Bluing and Browning" by RH Angier published by Samworth. Somewhat old fashioned but very good and still in print.

Eug
« Last Edit: October 02, 2014, 12:15:13 PM by Eugene »

Offline chipenter

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Re: Bluing steel
« Reply #2 on: October 02, 2014, 03:27:45 PM »
For small parts of clocks I use a tin half full of sand , heated from below and droped in oil as soon as the right color is reached , or tinmans solder is the same temp as blue steel , oil blacking is a higher temp droped into the dirtyist
engine oil you can find and lasts longer than blueing .
Jeff

Offline stovebolt

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Re: Bluing steel
« Reply #3 on: October 02, 2014, 03:29:28 PM »
  Hi Mick,
  I do bluing/ black oxiding using the caustic soda/ sodium hydroxide / lye  solution.  It is very caustic.
  If you want to go that route you may be able to get a local drain cleaner with both of the main  ingredients,
  the first 2 ingredients on this MSDS are what you need the last 2 not needed and I've read that aluminium will actually kill the salts. 

http://www.summitbrands.com/summit/downloads/msds/usa/MSDS%20Drain%20Out%20Crystal.pdf 
 
 But if you are not in a hurry, there is a slow rust bluing process.

 Degrease the part,  let it rust, shouldn't be a problem in Thailand, you can speed up the process by suspending the part in a bucket with  some water in the bottom , cover and let set a day or two,   boil the part in plain water, then using 0000 steel wool  and oil gently polish.  repeat  the process  4 or 5 times  or
until you are satisfied. 

Here's another method  , reverse electrolytic rust removal

http://castboolits.gunloads.com/showthread.php?137610-New-take-on-quot-slow-quot-rust-bluing         

Offline DavidA

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Re: Bluing steel
« Reply #4 on: October 02, 2014, 03:42:38 PM »
Stovebolt,

Re   I do bluing/ black oxiding using the caustic soda/ sodium hydroxide / lye  solution.

I'm not sure how to read that.

You do know that the three substances in that line of text are all synonyms for the same chemical ?

I.e NaOH.

Dave

Online John Rudd

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Re: Bluing steel
« Reply #5 on: October 02, 2014, 04:23:54 PM »
oil blacking is a higher temp droped into the dirtyist
engine oil you can find and lasts longer than blueing .
...and thats what I do to small parts....makes them look better than being rusty...
eccentric millionaire financed by 'er indoors
Location:  Backworth Newcastle

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Offline stovebolt

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Re: Bluing steel
« Reply #6 on: October 02, 2014, 11:11:49 PM »
Stovebolt,

Re   I do bluing/ black oxiding using the caustic soda/ sodium hydroxide / lye  solution.

I'm not sure how to read that.

You do know that the three substances in that line of text are all synonyms for the same chemical ?

I.e NaOH.

Dave


 Hi Dave,
  Yes, I just wanted to cover all the bases incase someone less acquainted reads this thread.    I've encountered that in the past. 

  Jim       

Offline Bangkok Mick

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Re: Bluing steel
« Reply #7 on: October 03, 2014, 03:49:08 AM »
Ok thanks for the tips guys, this is something to go on.

Cheers Mick

Offline Jonny

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Re: Bluing steel
« Reply #8 on: October 05, 2014, 03:06:00 PM »
For small parts of clocks I use a tin half full of sand , heated from below and droped in oil as soon as the right color is reached , or tinmans solder is the same temp as blue steel , oil blacking is a higher temp droped into the dirtyist
engine oil you can find and lasts longer than blueing .

Quite the opposite most non synthetic oils burn around the 130 to 160 degree mark, Whale oil 150 degrees.
To turn steels blue your looking at least 265 degrees and by 280 degrees its very light blue.
Also no need to place on sand that only disperses the heat making it more even once eventually warms up.
Blow lamp direct quite adequate and dump in anything to cool, good enough for Purdeys.

Hot browning, sorry blacking or blueing may not take to the steel its made from. Usually a low quality works better. Book linked to above I have here borrowed from a mate in 1992, nothings been available for 70 years or if it is you will be refused supply of some highly restricted chemicals. Proper quality salts are available over here from 40 a bag to 120 going back 6 years.
Assuming the item is made from steel best option take it to a metal finishers, its not worth the hassle. Horrible job any way.

Cold blacking is around 100 degrees parts have to be boiled repeatedly mainly for quality English shotguns where you don't want the barrels to part as they are soft soldered. Easy enough to do and can still give a highish gloss dependant upon the preparation.

Kits you get are mostly a waste of money, so are the cold blacking stuff ok for touching up screw heads.