I would like to hear opinions from you binocular experts.
I had been thinking one clue to tell the manufactured date of German military optical equipments is their lubricant markings. It is known that the Wehrmacht adopted several types of cold-resistant greases according to their inexperience with extraordinary cold-temperature, especially at the Eastern front. Improvements were continued from early to late war and according to the newly adopted cold-resistant grease, new marking was applied on the optical equipments. The marking is as the following.
1. "K.F."
The earliest marking seen on optics. It indicates the optic is lubricated with cold resistant grease "Invarol", which is said to be serviceable to -20 degrees C. I have heard this grease was adopted on <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:date Month="5" Day="27" Year="1940">27th May 1940</st1:date> (Have not yet confirmed it myself).
2. "O" (hellblaue Kreisfläche or light blue circle)
The next marking indicated new cold resistant grease, Vacuum grease (Vakuumfett) 1416, suitable for use under lower temperatures as to -40 degrees C. The earliest document referring to this "O" is the German manual for winter warfare "Taschenbuch für den Winterkrieg", first version dated <st1:date Month="8" Day="5" Year="1942">5th August 1942</st1:date>.
3. "+" (hellblaues Kreuz or light blue cross)
It seems that the Vakuumfett 1416 was somehow turned out to be unsatisfied soon, since on the revised version of the "Taschenbuch für den Winterkrieg" dated <st1:date Month="11" Day="1" Year="1942">1st November 1942</st1:date>, another marking "+" was mentioned. Although there is no explanation for the reason of the adoption, it is said that with the mark the instrument is perfectly serviceable to -40 degrees C and "in Zukunft wird das gesamte Beobachtungs und Vermessungsgerät des Heeres nur mit Instrumentenfett 1442 gefettet (in the future, all observation and surveying instruments of the Army will be only lubricated with instrument grease 1442)".
4. Light blue triangle
Yet, another marking appeared in the late 1943. I have not been able to find any document referring to the "triangle", the name of the grease and its suitability. But I have heard it was suitable for use between -40 degrees C and 50 degrees C.
Although the exact date of the grease adoption at the factory could be different by manufacturers, it is clear that they were adopted in this order. The date of the document does not show the exact date of the adoption, but one can assume they are nearby. So this leads me to a very rough estimation of the manufactured date of the optical equipments according to the lubricant markings.
K.F. : 1940-41
O : 1942
+ : 1942-43-44 (mainly in 1943)
Triangle : 1943-44-45 (mainly in 1944)
Another thing to mention. It is known that the marking was often added later when the instrument was repaired or maintained and re-greased. So it is not rare to see optics with double, or more, lubricant markings applied. But if one knows which marking is the earliest and can tell it is original from the factory, he can assume its rough date from my estimation. The study of the other markings on the instruments about its pattern and variation would help this.
I don't have enough information yet. If you have any information (or original documents) on these lubricant markings especially about "K.F." and "Triangle", please let me know. And any opinion is greatly appreciated.
Regards, Ken<O
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I had been thinking one clue to tell the manufactured date of German military optical equipments is their lubricant markings. It is known that the Wehrmacht adopted several types of cold-resistant greases according to their inexperience with extraordinary cold-temperature, especially at the Eastern front. Improvements were continued from early to late war and according to the newly adopted cold-resistant grease, new marking was applied on the optical equipments. The marking is as the following.
1. "K.F."
The earliest marking seen on optics. It indicates the optic is lubricated with cold resistant grease "Invarol", which is said to be serviceable to -20 degrees C. I have heard this grease was adopted on <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:date Month="5" Day="27" Year="1940">27th May 1940</st1:date> (Have not yet confirmed it myself).
2. "O" (hellblaue Kreisfläche or light blue circle)
The next marking indicated new cold resistant grease, Vacuum grease (Vakuumfett) 1416, suitable for use under lower temperatures as to -40 degrees C. The earliest document referring to this "O" is the German manual for winter warfare "Taschenbuch für den Winterkrieg", first version dated <st1:date Month="8" Day="5" Year="1942">5th August 1942</st1:date>.
3. "+" (hellblaues Kreuz or light blue cross)
It seems that the Vakuumfett 1416 was somehow turned out to be unsatisfied soon, since on the revised version of the "Taschenbuch für den Winterkrieg" dated <st1:date Month="11" Day="1" Year="1942">1st November 1942</st1:date>, another marking "+" was mentioned. Although there is no explanation for the reason of the adoption, it is said that with the mark the instrument is perfectly serviceable to -40 degrees C and "in Zukunft wird das gesamte Beobachtungs und Vermessungsgerät des Heeres nur mit Instrumentenfett 1442 gefettet (in the future, all observation and surveying instruments of the Army will be only lubricated with instrument grease 1442)".
4. Light blue triangle
Yet, another marking appeared in the late 1943. I have not been able to find any document referring to the "triangle", the name of the grease and its suitability. But I have heard it was suitable for use between -40 degrees C and 50 degrees C.
Although the exact date of the grease adoption at the factory could be different by manufacturers, it is clear that they were adopted in this order. The date of the document does not show the exact date of the adoption, but one can assume they are nearby. So this leads me to a very rough estimation of the manufactured date of the optical equipments according to the lubricant markings.
K.F. : 1940-41
O : 1942
+ : 1942-43-44 (mainly in 1943)
Triangle : 1943-44-45 (mainly in 1944)
Another thing to mention. It is known that the marking was often added later when the instrument was repaired or maintained and re-greased. So it is not rare to see optics with double, or more, lubricant markings applied. But if one knows which marking is the earliest and can tell it is original from the factory, he can assume its rough date from my estimation. The study of the other markings on the instruments about its pattern and variation would help this.
I don't have enough information yet. If you have any information (or original documents) on these lubricant markings especially about "K.F." and "Triangle", please let me know. And any opinion is greatly appreciated.
Regards, Ken<O
</O
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