Paper in Mineral oil.
in oil construction is one of the original and most
reliable oil types. Jupiter uses the finest quality
highly refined USP-grade mineral oils. Hermetically
Sealed and processed under a deep vacuum for several
days. Hermetic sealing keeps oil from leaking out and
provides protection from ingress of moisture to ensure
Glass to metal end seals are soldered into tin-plated
brass tubes to form leak-tight joints. Jupiter Silver
Foil Comet capacitors are built to Mil-Spec standards
yet developed and refined for sonic perfection.
in the USA of materials from USA and Germany
5N Silver wire
best results keep capacitors as cool as possible, use
common sense. Do not place next to or touching hot resistors
or under-chassis signal tubes that get hot etc. This
is good practice to follow with any capacitors, especially
paper capacitors. Generally for every 10 degree C increase,
component life is diminished by half.