Metallurgy in the Peruvian Andes was noted for the emphasis that was placed on producing hammered objects. This technological preference was a cultural choice, and it did not depend on the properties of the metals or in ignorance of other techniques, for they knew about melting, which they performed before they took up hammering. The Andean tradition spread throughout the territory now known as Colombia, and particularly in its south west region.

In order to make sheets, goldsmiths hit ingots against stone slabs or anvils. They used hammers of different shapes, materials, sizes and weights, depending on the alloy, the size of the object, or the phase of the work.

The metal becomes brittle and tends to fracture when it was hammered. The goldsmiths had to heat it until it was red hot and then cool it by submerging it in water. This process –annealing– was repeated many times, and it allowed that the sheet could go on being hit until the desired thickness and size were attained.

Stone polishers and slabs were used to smooth the sheets and thus obtain uniform surfaces. Stone or hammer-hardened tumbaga chisels were used for marking out the object and cutting it to its final shape.

The highly malleable nature of gold meant that thin, flexible sheets could be manufactured for making objects of varying shapes, sizes and calibres. Silver was used only on the high plains of Nariño, where the cultural influence of the Central Andes was felt. Nose rings, earrings, containers and diadems were made from copper and silver alloys.

The craftsman sketched the decorative design on the back of the sheet with an engraving chisel. Then, with the help of punches, embossing tools and ordinary chisels, he pressed and highlighted the motif on both surfaces, while resting the object against some soft material or against shapes carved in clay, wood or bone.

Designs with spaces or openwork were obtained by cutting sheets with the aid of metal and stone chisels.

The Tumaco - La Tolita region, on the Pacific coast of Colombia and Ecuador, was the only part of America where platinum was used. Since the metalworkers could not cast platinum, due to its high fusion point of 1775°C, they developed the sintering process. When granules of platinum mixed with gold were heated, the gold melted and trapped the platinum; the resulting ingot could be worked by hammering it. In the metallographic microscope we can see how the grains of platinum are trapped by the cast gold.

The goldsmiths of the Colombian south west combined gold and sintered platinum parts to create two-coloured ornaments.

One notable feature of pre-Hispanic Colombian goldwork was the predominant role that was played by casting using the lost wax method. Goldsmiths were masters at shaping ornaments and containers in wax with their hands and then transforming them into metal. The wax was obtained from beehives that housed bees with no sting, or "little angel bees". Various species of these are found in Colombia, at heights ranging from sea level up to 3,400 metres, particularly in rainforests.

By forming a shape in beeswax and then using a mould to transfer that shape into metal, goldsmiths created a wide range of objects: realistic or abstract representations, fine metallic weaves, or heavy ornaments.

The fingerprints imprinted into some metal pendants led Europeans to think that indigenous groups moulded and modelled gold directly with their hands. The fingerprints were left in the wax models that were used in the casting using the lost wax method.

• The desired figure was modelled in wax. Coils of the same material were added to the model, and when the wax melted, these would leave pipes through which the metal would flow.
• The wax model was coated with layers of clay to form the mould. When the mould was dry and hard, it was heated so that the wax would melt and it could be removed.
• Liquid metal was poured into the mould. It thus took on the shape of the model.
• When the mould was cool, it had to be broken to remove the metal object.
• When the object was removed from the mould, the pipes and the funnel were cut, and the object was polished; traces of these can still be seen in some objects.
  

De la manera de labrar los plateros

Fundiciones especiales

In some societies, goldsmiths preferred to create volume by using hammered sheets, which they assembled with the aid of wires, nails or bends. They also experimented until they discovered how they could join parts by heating the surfaces or by using substances which helped form joints between the metals.

In the hands of the skilled craftsmen, gold easily took on the shapes of the models that had been made beforehand from wood, bone or clay. The embossed sheets were joined together or assembled, to create volume. The model tended to be removed, although it could remain under the metal.

Delicate necklace beads, nose rings and ordinary rings were made by joining miniature gold spheres together using the granulation process.

The beads were stuck together using an organic glue that was mixed with copper oxides. The glue was carbonised using fire, and the copper helped join the spheres together at a temperature below their fusion point, thereby preventing them getting deformed.

Fire-resistant pottery mould found in the Calima region. The gold that was cast into its hollows formed small balls, which were then joined together by granulation.