Granulation (jewellery)

This technique then spread to southern Europe during the orientalizing period, also through the role of Phoenicians, who had founded colonies in Sardinia, Sicily and Spain, or Near Eastern craftsmen.

Greek craftsmen also employed the technique, but it was the work coming from Etruria which became famous, in part due to the mysteries surrounding the process.

It is then fired in a reducing kiln causing the tragacanth to burn off and release the copper salt.

The granules are positioned using a diluted flux and fine brush, after which the sheet is fired in a reducing oven.

At melting temperature the granules and sheet metal fuse, leaving no flux or solder.

Soldering is routinely used by bench jewellers and is an ancient technique but is applied with great difficulty to small metal grains.

The necessity of repeating this process many hundreds of times renders the technique impractical and expensive, complicated by the possibility of dislodging granules already attached.

Although the exact technique remains a mystery, colloidal soldering is the most recognized and coveted due to its resemblance to the original ancient pieces when analyzed using chemical and advanced imaging methods.