Salt Blueing~

cirelaw · 12-24-2018, 12:03 PM

How does this process differ from all the rest and when and on which lugers was it used? Eric

cirelaw · 12-24-2018, 12:08 PM

I found this~ http://www.rustblue.com/about/instructions/ A real detailed process! Eric

cirelaw · 12-24-2018, 12:23 PM

Explained! https://en.wikipedia.org/wiki/Bluing_%28steel%29

mrerick · 12-24-2018, 12:33 PM

I think that salt based bluing accelerates the controlled oxidation process, probably creating a higher percentage of the blue-black mode of Iron Oxide than the slow rust and card process in the older more manually intensive Rust bluing processes.

The WikiPedia article you found has a pretty good explanation of the different oxidation modes of iron, and why Magnetite (the blue-black mode of Iron Oxide) is a desired finish. Getting there is, of course, half the fun...

As contrasted to the rust bluing process you found described online, salt bluing is done in warmed baths of mixes of chemicals followed by polishing steps.

Brownells has a pretty good summary of the modern process here:

https://www.brownells.com/aspx/learn...aspx?lid=11044

The chemical bath contents and mix levels have varied over the long development of an efficient process, and this also was impacted by the alloy content of the steels being treated (leading to color variations with certain chemical mixes).

Mauser started shifting military contract Lugers to Salt Bluing in 1937, with a mix of characteristics coming over the first part of that year. I'm pretty sure Krieghoff Lugers were salt blued as well but could be mistaken about that.

All my post war modern Mauser Lugers were salt blued.

Even after 1937, Mauser commercial Lugers were rust blued, appearing with strawed small parts. It must have been considered a premium finish at that point. Here's a photo of the rust blued frame from a 1938 dated .30 Luger Mauser pistol from late in the "w" block and a 1938 Military contract Mauser Luger frame and receiver which were salt blued. You can see the metal still in the white inside the commercial Luger frame where the bluing chemicals were never applied. The Military contract Luger shows the bluing throughout the interior of the frame.

cirelaw · 12-24-2018, 01:23 PM

Mauser does an excellent job!! Tks for your valuable info!! Merry Christmas!

DonVoigt · 12-24-2018, 01:51 PM

"As contrasted to the rust bluing process you found described online, salt bluing is done in warmed baths of mixes of chemicals followed by polishing steps. "

No,
items to be hot blued must be polished or "prepared" before bluing. If polished after, all the blue color- which is a very thin "coating" or reacted layer as you described, will be removed and one is back to the "white" state of un-finished metal.

As we all know from experience, hot blue is not a very durable finish; rust blue is a little better as the surface is etched during application.

12-24-2018, 12:03 PM	#1
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Salt Blueing~ How does this process differ from all the rest and when and on which lugers was it used? Eric

12-24-2018, 12:33 PM	#4
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,900 Thanks: 1,372 Thanked 3,094 Times in 1,503 Posts	I think that salt based bluing accelerates the controlled oxidation process, probably creating a higher percentage of the blue-black mode of Iron Oxide than the slow rust and card process in the older more manually intensive Rust bluing processes. The WikiPedia article you found has a pretty good explanation of the different oxidation modes of iron, and why Magnetite (the blue-black mode of Iron Oxide) is a desired finish. Getting there is, of course, half the fun... As contrasted to the rust bluing process you found described online, salt bluing is done in warmed baths of mixes of chemicals followed by polishing steps. Brownells has a pretty good summary of the modern process here: https://www.brownells.com/aspx/learn...aspx?lid=11044 The chemical bath contents and mix levels have varied over the long development of an efficient process, and this also was impacted by the alloy content of the steels being treated (leading to color variations with certain chemical mixes). Mauser started shifting military contract Lugers to Salt Bluing in 1937, with a mix of characteristics coming over the first part of that year. I'm pretty sure Krieghoff Lugers were salt blued as well but could be mistaken about that. All my post war modern Mauser Lugers were salt blued. Even after 1937, Mauser commercial Lugers were rust blued, appearing with strawed small parts. It must have been considered a premium finish at that point. Here's a photo of the rust blued frame from a 1938 dated .30 Luger Mauser pistol from late in the "w" block and a 1938 Military contract Mauser Luger frame and receiver which were salt blued. You can see the metal still in the white inside the commercial Luger frame where the bluing chemicals were never applied. The Military contract Luger shows the bluing throughout the interior of the frame. Attached Thumbnails __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.

12-24-2018, 01:51 PM	#6
DonVoigt User Join Date: Apr 2015 Location: near Charlotte NC Posts: 4,677 Thanks: 1,440 Thanked 4,348 Times in 2,038 Posts	"As contrasted to the rust bluing process you found described online, salt bluing is done in warmed baths of mixes of chemicals followed by polishing steps. " No, items to be hot blued must be polished or "prepared" before bluing. If polished after, all the blue color- which is a very thin "coating" or reacted layer as you described, will be removed and one is back to the "white" state of un-finished metal. As we all know from experience, hot blue is not a very durable finish; rust blue is a little better as the surface is etched during application. __________________ 03man(Don Voigt); Luger student and collector. Looking for DWM side plate: 69 ; Dreyse 1907 pistol K.S. Gendarmerie

12-24-2018, 12:08 PM	#2
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	I found this~ http://www.rustblue.com/about/instructions/ A real detailed process! Eric

12-24-2018, 12:23 PM	#3
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Explained! https://en.wikipedia.org/wiki/Bluing_%28steel%29

12-24-2018, 01:23 PM	#5
cirelaw Lifer Lifetime Forum Patron Join Date: Dec 2003 Location: PORT ST LUCIE, FLORIDA Posts: 12,216 Thanks: 6,209 Thanked 4,133 Times in 2,173 Posts	Mauser does an excellent job!! Tks for your valuable info!! Merry Christmas!