It's an obscure story, little known and seldom told.
During WWII all Braunviolette paint for the Luftwaffe was manufactured at the Dingeldrubber Farbenwerke in Fahrzenschiz Austria. From early 1943, production at the Farbenwerke was carried out mainly by foreign slave workers. This work force was infiltrated and organized by the notorious Rote Kazoo espionage network.
Under the direction of Rote Kazoo, workers at the Farbenwerke sabotaged production by urinating in the vats of paint. The sabotage led to wide variations in color, due to varying degrees of adulteration.
The sabotage drove the Luftwaffe crazy. Since every batch of paint coming from the Farbenwerke was different, the Luftwaffe was never able to establish a standard shade of Braunviolette. Base commanders scrambled frantically to repaint aircraft with the latest batch of Braunviolette received from the Farbenwerke. The confusion and waste of labor led to a 7% reduction in night fighter availability from mid-1943, and proved to be the most signal success of the Rote Kazoo sabotage campaign.
The startling fact is that every shade of Braunviolette you own is correct for some batch of the adulterated paint. Use them all with confidence.
If you wish, you can create your own unique and authentic Braunviolette by adding urine to the paint, either your own or any conveniently available. Unless you have ninja-like control of your urine stream, I recommend you don't pee directly into the paint bottle. Whiz instead into a container like a coffee cup (not your own!) and use an eye dropper or oral pipette to transfer small amounts of urine to the paint bottle. Continue peeing in the paint until you like the color.
ponders nirvana.