vaakummärken
Vaakummärken is a Swedish term that translates to "vacuum marks" or "vacuum signs." In a historical context, it refers to the visible evidence of how a vacuum was created or maintained in a sealed container, particularly in early vacuum tube technology. These marks could be physical imperfections or residue left behind from the manufacturing process.
During the development of incandescent light bulbs and early electronic tubes, achieving and maintaining a high
Collectors and historians of antique scientific instruments and early electronics sometimes identify vaakummärken as indicators of