Copper is a metal with a characteristic red colour, and is similar to gold and silver for its chemical-physical properties. Extremely ductile and malleable, and an excellent conductor of heat and electricity, it is currently used in the pure state and in alloys (such as bronze and brass) in many applications (gift articles and crafts, plumbing/heating systems, electronics, protective coatings, coins, architecture, etc.).

Copper is found in the native state almost pure: it was one of the first metals discovered and used by man, and is easy to work even cold simply by beating with a hammer.

The symbol of this metal, Cu (Cuprum) and its name in different Western languages (English copper, French cuivre, German kupfer, Spanish cobre) comes from the island of Cyprus (Latin Cyprum), which was one of the main centres for the production and export of copper; whereas its Italian name rame comes from the Latin aeramen.

Cyprus was also the main centre of worship of Aphrodite, the goddess of love and beauty, the Venus of Roman religion. In alchemy, the symbol for copper is the mirror of Venus, a circle with a cross pointing down, which coincides with the symbol of the planet Venus and therefore with the feminine symbol.

Figure 1: The alchemical symbol for copper

The elements of stills for distilling grappa are traditionally made of copper for various reasons:

primarily because copper binds chemically with several sulphur compounds that are naturally present in the marc, in being produced by the microorganisms of alcoholic fermentation and following the possible use of sulphur dioxide as an antiseptic and antioxidant in the grape vinification stage. During distillation, insoluble copper compounds are thus formed which chemically bind some unpleasant smelling molecules containing sulphur. These compounds precipitate to the bottom of the columns of the still and are discarded with the distillation waste, thereby not entering the distillate.

If, however, the still was not made of copper, these substances would compromise the organoleptic properties of the distillate and give it an unpleasant odour such as that typical of bad eggs, due to the presence of free sulphuric acid, or a putrid and waxy smell due to the presence of mercaptans.

The walls of the still are therefore a vital part that continues to interact with the distillate, gradually becoming consumed. A copper still therefore requires constant maintenance.

Copper also is a good conductor of heat. It can withstand high temperatures, because it melts at 1083°C, and does not deform or break even when subjected to considerable temperature fluctuations. In a copper boiler, the heat is distributed quickly and evenly. The mass to be distilled does not burn, because the heat is not concentrated in a single area but is distributed over the entire surface. The rapid increase in temperature favours reaching of the evaporation point of the various volatile compounds contained in the raw material, without them forming unpleasant empyreumatic compounds which would give the distilled a baked and burnt smell.

Copper is very malleable and ductile (i.e. the ability to be rolled and drawn). It can therefore be easily worked to create curved surfaces such as those of the elements of stills. For example, rolled copper sheet is used for the boiler shell, whose rounded shape serves to evenly distribute the heat.

Copper is corrosion resistant: a metal that is highly resistant to the alcohol vapours produced during distillation. Furthermore, copper is highly resistant to marc and fruit acids. It does not give the distillate a metallic taste and helps neutralise any unpleasant odours and tastes.

Lastly, copper is 100% recyclable. More than 40% of the copper currently used in Italy comes from recycling. Recycled copper has the same chemical-physical and technological properties as primary copper.