Hot blue

U.S. Military Krags
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waterman
Posts: 447
Joined: Fri Oct 07, 2011 4:29 pm

Hot blue

Post by waterman »

I started this topic and put it here because I don't want to hijack the thread on the restoration of two Krags. One of the OP's later comments mentioned hot blue. My first thought was "OMG, they might turn color!"

When I was in my teens in the late 1950s, I hung out as an unpaid apprentice in a gunshop that did a lot of hot bluing. Krag sporters were pretty commonly brought in for re-bluing. Receivers often turned a shiny deep maroon color. This was so common that the color was called "Kraggy".

Ten years later and half a continent away, I went to college on the GI Bill. At college, I met another lad, like me a Krag enthusiast. We soon made the rounds of all the decent gunshops within a reasonable driving distance. We saw lots of reblued Krags, many having that same color. My friend also called that maroon color "Kraggy" and he didn't learn it from me. It must have been a fairly common term used by those of us who hung out in gunshops.

I haven't heard the term in years, but it popped into my head when I read the last post. What caused the color and why?

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P0H0
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Location: Northeast Ohio

Re: Hot blue

Post by P0H0 »

When I think of Hot Bluing, I am thinking of the modern bluing process with the salts in hot tanks. I know the general bluing options as Hot Blue, Cold Blue, and Rust Blue. Within the Hot Blue category, you can get a finish done with a high polish, standard polish, or matte (blasted to rough up the surface). As some background to assist with understanding the “Kraggy” look, different metals will blue differently. In regards to the Krags and 1903 Springfields, the receivers, were case hardened — this is different than color casing in that the part is quenched in oil (sperm oil back in the day) as opposed to water. A part that is quenched in oil will have a black color to it as opposed to color cased which will show colors (like an oil slick I guess). Hot bluing a case hardened surface will yield a look slightly different also — I wonder if this is the cause of the “kraggy” look? The rifles I am restoring are being rust blued and should not have kraggy color to them (I hope).

I have seen some restored Krags that have been hot blued — I don’t recall them being a different “kraggy” color, perhaps it also has to do with the salts being used? Do you have a picture of one?

Color Case Hardened (Water Quench):
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Case Hardened (Oil Quench):
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I have a German 98K that is blued and has an extractor that looks plum colored after it was heat treated — I have read this is normal.
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P0H0
Posts: 243
Joined: Sun Dec 25, 2022 9:52 pm
Location: Northeast Ohio

Re: Hot blue

Post by P0H0 »

Here is a post I found describing something similar:

https://www.finishing.com/116/28.shtml
Q. Help needed on bluing that turned out red-purple. I have recently started bluing and repairing guns as a hobby. I have run across a problem. I blued a Winchester 94 using Brownell's Oxynate No. 7. and added Oxynate "S". The barrel is a nice black but the receiver turned a red-purple. Can anyone help? How can I correct this? Thank you,

J.W. McGuire
- Ashville, Alabama, USA

2001
A. You have just discovered one of the facts of life, not all steels will blue with Oxynate 7, you can do one of the following, iron plate the receiver, then blue, get some Oxynate 7., or just Parkerize .
the whole thing, (this is the easiest answer)

Dennis Burke
- Arley, Alabama

September 3, 2021
A. Old Win 94's have a multi alloy steel receiver different then the barrel. The receiver is actually painted and baked in high temp at the factory and the barrel is hot blued. I have used a lower temp in the bluing tank for the receiver and carded the receiver with hard brown paper and comes out decent. Lots of trial and error

Mike Pucci
Gunsmith - Shickshinny Pennsylvania

waterman
Posts: 447
Joined: Fri Oct 07, 2011 4:29 pm

Re: Hot blue

Post by waterman »

The red-purple described and the color of the Mauser extractor in the photo are very close to the "Kraggy" color, except that the Krag receivers, if well polished, were quite shiny. I've always assumed that it was a chemical reaction of the bluing salts on the case-hardened steel surface.

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