I have seen many queries about Aida brand in older posts on the forum. I once upon a time heard this story, I wanted to post it up and see if anyone else here has heard it:
Aida was a trademark owned by one Jakob Hirschhorn AG, a Barvarian manufacturer of outdoor sporting goods. Aida had invented the "rapid" preheater, which Aida called the "express" which was to solve the preheating problem with the original gas pressure lantern designed by Max Graetz. I am told that this was because of a complaint by the German army that the lamp was difficult to start but otherwise excellent. Through the agency of the army contract, Aida and E&G co-operated on the upgrading of the lantern an standardization of their respective variants, which are very similar but not identical.
During the rise of the Nazis, Hirschhorn had a dilemma. He was Jewish and needed to close his business and leave Germany. His company was acquired by the Graetz brothers (E&G's proprietors) who bought it for full market price - which they did not need to do, but did anyway to help their friend. They quietly retired the Aida tooling, and kept it in storage near the original Aida plant during the war.
After the war, E&G found itself in the Soviet occupation zone. The Russians seized their tooling and moved their factory to the east, leaving them with nothing. But the Graetz brothers had an ace in the hole - the Aida tooling was in the Western zone, unscathed by the war.
Because of their kindness to their friend Jakob in his time of need, his old tooling was there for them to relaunch Petromax after the war. It was the hand of God. This is the reason that the Aida express reappeared after the war before the Petromax rapid did. Once they had made enough money to make new tooling, they started making new Petromax rapids on an assembly line next to the Aida expresses. They again quietly retired the Aida tooling after the Petromax line was fully in production, and so Aida faded into history.
That's the way I heard it. If anyone out there knows different - I'd love to hear it.