Durchschlag

Durchschlag is a German noun with several related but distinct meanings, depending on context. Etymologically, it combines durch (through) and Schlag (blow or strike), and historically it referred to something that is passed through or left on the other side.

In everyday and administrative use, a Durchschlag is a carbon copy of a document produced together with the original, typically by carbon paper. In old office practice, the original and one or more Durchschläge were created simultaneously, so multiple copies could be distributed. Today the term survives mainly in historical or legal phrasing, since photocopying and digital archiving have largely replaced physical carbon copies. The Urschrift means the original, while the Durchschläge are the copies.

In technical contexts, Durchschlag denotes a breakdown or penetration event. In electrical engineering, the term is used for insulation breakdown, with quantities such as Durchschlagsspannung (breakdown voltage) or Durchschlagsfestigkeit (dielectric strength) indicating the voltage or field strength at which an insulating material becomes conductive. In materials testing and high-voltage design, measuring the Durchschlag is essential for safety and reliability.

In ballistics and related fields, Durchschlag can also refer to penetration of a barrier by a projectile or energy source. Terms like Durchschlagskraft or Durchschlagsvermögen describe the penetrative capability of a weapon or material.

Overall, Durchschlag spans practical copies in historical document handling and several technical senses involving passage through a barrier or medium, while retaining the core idea of something capable of passing through or leaving a trace on the other side.