A highly skilled potter, smith or weaver did not necessarily practise their craft full-time. Production could take place within a household, alongside farming and other activities, or in workshops supplying objects to a much wider community. Archaeologists search for concentrations of tools, furnaces, moulds, raw materials and production waste. They also examine the scale of production, the similarity of finished objects and the distances over which they travelled. None of these clues alone proves that specialised production existed.

Finding a furnace, a mould or a group of similar objects does not automatically prove that specialised craftspeople were at work. Craft specialisation concerns the organisation of production: who made particular objects, how much time they devoted to this work and who received the finished products. One influential definition describes it as the production of durable goods intended for exchange outside the producer’s immediate household. A skilled potter or weaver working exclusively for their family would therefore not necessarily be considered a specialist, while someone supplying other households might be one. This did not always mean abandoning farming or working in a craft throughout the year. Production could remain seasonal and be combined with other duties.

Specialists could operate independently, acquiring raw materials, organising their workshops and distributing their own products, or remain attached to an elite, a ruler or another institution. In the latter case, a patron might provide materials and tools, control access to the workshop and decide who received the finished objects. The same craft could be organised in different ways depending on local demand, access to resources and social relationships. An elaborate object was not necessarily produced under elite supervision, just as the wide distribution of a product does not prove that its maker worked independently.

Archaeologists consequently look for several kinds of evidence at once. Large concentrations of unfinished objects, failed products, moulds, slag, ceramic wasters and prepared raw materials may indicate production exceeding the needs of one household. Kilns, furnaces and other permanent installations can support this interpretation, as can the similarity of objects made in considerable numbers. Yet standardisation alone is not enough: similar products may reflect shared conventions or repeated domestic practice. The location of production is equally important. Some workshops were separated from houses because they generated heat, smoke and waste, while others were integrated into domestic areas. Highly skilled craftspeople could also work with simple, portable tools and leave few recognisable traces.

Specialisation depended above all on knowledge acquired through observation and repeated practice. Complex skills consisted of gestures, experience and decisions that could not be copied simply by examining a finished object. Some craftspeople may therefore have travelled between settlements, while others passed their knowledge on through teaching, migration or long-term contact. This question is particularly important for our project. When an object with a northern form appears in a La Tène context, it may have arrived through exchange, but it could also have been made locally by a travelling craftsperson or by someone familiar with different technological traditions. By examining raw materials, manufacturing traces and technological choices, archaeologists can ask whether only objects travelled or whether people and their skills moved with them.