Molten copper

Molten copper is the melted, liquid form of copper ore that has been smelted by a foundry. On Vulcanus, molten copper can also be generated by processing lava. Both methods of generating molten copper require calcite. Molten copper cannot be placed into barrels, so it cannot be sent to other planets.

Once generated, molten copper can be cast into copper plates, but it can also be cast directly into copper cables or low density structure. The copper cable casting recipe is always more efficient compared to casting plate and using an assembling machine, but not as efficient as using the electromagnetic plant with productivity modules of sufficiently high quality.

A fluid wagon of molten copper represents more copper plates than a single cargo wagon can store. Even without productivity modules, 50,000 molten copper represents 7500 copper plates, nearly twice the storage of a cargo wagon (4000 copper plates). Additionally, even with legendary quality productivity module 3s, the 2000 copper ore that fills up a single cargo wagon would only generate 50,000 molten copper, the exact size of a fluid wagon. So fluid wagons always at least as efficient per wagon as ore or plate.