Author Topic: Rust bluing experiments, think I've figured it out.  (Read 20564 times)

Offline Rolf

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Rust bluing experiments, think I've figured it out.
« on: March 30, 2010, 11:55:03 AM »
I did a pile of tests on different home brewed rusting solutions. The test were done on pieces of hot rolled mild steel polished to 320 and 400 grit.

Regarding to polishing :
There was no difference regarding to rusting action and color on 320 and 400 grit. But 400 grit gave a smoother surface.

Rusting solution:
The two best solutions were Niedner blue and ferric chloride. Applied directly on steel these solutions gave far to aggressive pitting and uneven rusting , but work great when diluted with 96% alcohol. Both gave nice dark finishes. The nieder blue gave a smoother surface than ferric chloride. Ferric chloride did not effect silver. Niedner blue turned silver an ugly brown color. Its the nitric acid/iron part that does this.

Niedner blue base solution.
20ml cons. nitric acid + 17ml cons.HCl + 8grams iron + 260ml dist.water.
To make rusting solution, dilute base with 50/50 alcohol.

Ferric Cloride rusting solution.
Add iron to cons.Hcl until it stops reacting. Filter through a coffee filter. This gave a clear yellow solution. Take 25 ml of this and  add 125ml alcohol and 100ml dest.water.

Rusting, humidity,temp,time
Rusting was done in a large plastic bucket with a tight lid. Large sponge functioned as water reservoir. The bucket was kept in the washroom. The tests gave best results at 280C and 90 minutes rusting. No visible rust at 180C and 24 hours rusting.


Carding and boiling.
Carding was done with gorbet steel carding brush. It made no difference if I carded first ,then boiled or if I boiled first and carded afterwords. Tap water and distilled water gave the same results(we have soft water). What mattered was boiling time. The pieces had to be boiled 1 hour to convert all the rust to black rust. I took a test piece, did one round of rusting,carding and 30 minutes boiling. Then I sanded off the color with 400 grit and boiled  for 10 minutes and it blackend again. By repeating this, I found that one hour boiling is required to turn all the rust black.


Rusting and steel types
Ferric chloride gave poor results on caseharden screws. Neidner work better but needed eighth applications. The GM pistol barrel was alot easier to rust blue than the test pieces of mild steel. This is the barrel after two rounds of rusting with the ferric chloride rusting solution. The test piece next to it was rusted 8 times.


Best regards
Rolfkt
« Last Edit: March 29, 2022, 08:27:37 PM by rich pierce »

Offline Long John

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Re: Rust bluing experiments, think I've figured it out.
« Reply #1 on: March 30, 2010, 03:19:08 PM »
Rolf,

I suspect there are going to be a lot of us that copy your post and put it in a gun-making folder of one sort or another.  Thanks for sharing your experimentation with us!

Best Regards,

JMC

Offline rich pierce

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Re: Rust bluing experiments, think I've figured it out.
« Reply #2 on: March 30, 2010, 03:54:44 PM »
Make it a tutorial!
Andover, Vermont

Online JTR

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Re: Rust bluing experiments, think I've figured it out.
« Reply #3 on: March 30, 2010, 04:01:45 PM »
Nicely done bands on the barrel Rolf! :o
Silver or gold? I can't really tell from the picture. If gold, what carat?

John
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Offline Rolf

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Re: Rust bluing experiments, think I've figured it out.
« Reply #4 on: March 30, 2010, 10:32:27 PM »
Thanks for the kind words.
JRT, the bands are pure silver. It's the same barrel I used for the wedding band tutorial.

Best regards
Rolfkt

Offline Bill Weedman

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Re: Rust bluing experiments, think I've figured it out.
« Reply #5 on: March 31, 2010, 03:35:14 PM »
When I rust blued barrels I made a chamber with a vaporizer humidifier controlled by a humidistat and a light bulb on a thermostat with a timer to time power. Controlling the environment can dramatically change the effects....

It was a tall cabinet with a plexi window that I could check the process. Long barrels were easy and I made hangers for small parts with a shelf for parts that could not be hung.

An amazingly durable finish for rust blue or brown.

Offline Dphariss

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Re: Rust bluing experiments, think I've figured it out.
« Reply #6 on: March 31, 2010, 05:17:46 PM »
I have a 4140 GM barrel I have been rust bluing for quite some time now. Having started out with the wrong bottle of stuff ::)
This has been one of "those" jobs for those who know what I mean >:(  First the barrel never came maker sold business so it and 2 others never got made (a year shot) then. I had to order a GM and machine to profile, always fun, then it won't blue. But a friend in need.....
Two different formulas and OVER a month and finally got it blue enough to oil.
This has been the most frustrating one ever and I used to rust blue 4140-4150 all the time. Takes a few days.
I carded it yesterday after boiling then put in new plugs and boiled it again and it looked pretty good so I oiled it. At least I did not rust the bore.

I use a box I have screwed to the wall over a bench. I put open containers of water in there and usually a couple of acid bottles with the lids off to fume the part as well. Sometimes I turn on the 15 watt bulb for heat.

Dan
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Offline David Veith

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Re: Rust bluing experiments, think I've figured it out.
« Reply #7 on: April 01, 2010, 02:10:59 AM »
Niedner blue is it from a gun shop or some where else? I haven't done any blueing yet.
David Veith
David Veith

Offline Dphariss

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Re: Rust bluing experiments, think I've figured it out.
« Reply #8 on: April 01, 2010, 08:31:35 AM »
Niedner blue is it from a gun shop or some where else? I haven't done any blueing yet.
David Veith

Get Angier's "Firearms Bluing and Browning". It has a lot of formulas.
I use a mix similar to Niedner's with no alcohol.
I have used Wahkon Bay brown and AF stock stain mixed with pretty good results.

Dan
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Offline Rolf

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Re: Rust bluing experiments, think I've figured it out.
« Reply #9 on: April 01, 2010, 01:15:15 PM »
« Last Edit: April 01, 2010, 01:17:31 PM by Rolfkt »

Offline heinz

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Re: Rust bluing experiments, think I've figured it out.
« Reply #10 on: April 02, 2010, 01:34:47 AM »
"Get Angier's "Firearms Bluing and Browning". It has a lot of formulas."
Dan is right again, Angier's is a very useful text to have around the shop
kind regards, heinz

Offline David Veith

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Re: Rust bluing experiments, think I've figured it out.
« Reply #11 on: April 04, 2010, 02:47:21 AM »
Thanks. Angier's "Firearms Bluing and Browning". I didn't find it on Able books. So I guess I need more information on it.
Thanks
David
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Offline John Archer

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Re: Rust bluing experiments, think I've figured it out.
« Reply #12 on: April 04, 2010, 03:17:03 AM »
Amazon has a few copies. The correct title is "Firearm Blueing and Browning"  (no "s" on the end of Firearm)  by R H Angier.

John.
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