Patina...

[Pete Ebbink]

Received several questions from beginning luger nuts about what is meant by "patina under the bluing"...

Here is a good photo from Joe Salter's web site showing this feature that old lugers should display (to some extent) :

[Lugerdoc]

Pete, I would call the example in your photo "light scattered pitting" or in some cases "dings" rather than patina. When I think of patina (microscopic pitting) I think more of the typical "frosted" grip strap. TH

[Ron Wood]

Depending on the monitor that your computer system has, photos such as the one that Pete posted do not always display the effect that it is intended to illustrate. True â??patinaâ?� is difficult to photograph and more difficult to show on a computer screen. I have a high resolution graphics monitor, so many times I will be able to observe markings or features on Lugers that are posted that other Forum members say they cannot see.

Peteâ??s photo comes pretty close to illustrating patina accurately but not entirely. Patina is the brown undertone that shows up in an old rust blue finish.

To understand what patina is and what causes it, it is necessary to know some basic chemistry. I am no chemist, so the following blither is probably over simplification and I will likely, and justifiably, be taken to task by the more knowledgeable members.

Rust blue and patina are two sides of the same coin, i.e. they are both â??rustâ?�, or oxides of iron. The dark blue or black color of rust blue is Ferrous Oxide (with or without small amounts of Ferric Ferrous Oxide, but that is much more detail than is needed!). The red or brownish color of patina is Ferric Oxide.

The rust blue process starts out by a controlled rusting, or oxidation, of the metal using various combinations of acids and moisture to create a uniform coating of red Ferric Oxide. At the appropriate stage of rusting, the metal part is immersed in boiling water. This halts the oxidation process and converts the red rust to Ferrous Oxide rust producing the black color. The excess rust scale is removed, usually with steel wool or a soft steel wheel. If the process was properly performed, the result is a smooth surface with the desired blue/black appearance. The process sometimes is repeated several times until the desired depth of color is achieved.

This finish is quite durable, being actually a physical property of the metal surface, i.e. the finish is â??inâ?� the metal not â??onâ?� the metal. Properly lubricated and protected from atmospheric or environmental moisture (and even the oxygen in the air), further rusting is precluded and the original appearance can be preserved for a very long time. This is why there are some, albeit precious few, original â??mintâ?� finish pieces around that are the holy grail of collecting.

Here is where patina comes in. Left unprotected, or not adequately protected, the rusting process, specifically the production of Ferric Oxide, will continue to a greater or lesser extent depending on environment. This is red rust and will always be red rust. On a 60 to 100 or more year old gun this rust will take on different â??gradesâ?� of deterioration of the finish. The most desirable of course is â??patinaâ?�, a uniform very light red/brown discoloration (emphasis on â??uniformâ?�) of the blue that can only be detected in strong light, (e.g. Maglite or direct sunlight). The metal surface retains a polished look. This is the condition that collectors rely on to judge originality of a finish. Since lubricants and handling of the weapons invariably change over the years, even the â??holy grailsâ?� will usually exhibit trace amounts of this patina.

The other â??gradesâ?� of rust are far more invasive, although they are tolerable in small amounts. The rusting produces a tangible elevation of the surface material, sometimes referred to as â??scaleâ?�.

I consider a gun surface to be â??frostedâ?� when there are fairly thin and uniform areas of this raised scale that is very fine grained. The metal surface has been penetrated a minute amount, therefore the scale can be carefully cleaned off but the high polish of the surface has been deteriorated. The presence of this â??gradeâ?� of rust produces a light roughness that can be felt by dragging a fingernail over the surface.

â??Frecklingâ?� is a more scattered pattern of small areas that can range from the light roughness of â??frostâ?� to minute pitting that does not penetrate very far into the metal. If a gun is to be refinished, both freckling and frost usually can be removed with light abrasive materials that will preserve contours and markings if performed carefully.

The most serious â??gradeâ?� is of course â??pittingâ?�. Here the metal has been penetrated to a significant depth and the finished surface of the metal has been destroyed. Considerable metal removal is required to restore a smooth surface and may require building up with weld.

Thanks for letting me bend your ear (eyeball?).

[Luke]

Good tutorial, Ron. Thanks.
Luke

[Pete Ebbink]

Thanks, Ron !!!

I was just being lazy with posting one photo...always look forward to your learned discussions...!

It is much easier to show a fellow collector in person...

[Heinz]

As Ron notes, the effect of this "after rusting" can be brought out when doing an in person investigation by using a small maglight flashlight held at a low angle to the surface. Always take a double A maglight with you to gunshows. You can get educated pretty quickly. Also be aware that although the absence of patina can be strong evidence that a pistol is not old, the presence of patina beneath the blue is NOT proof that the bluing is original. It can be produced.