Maitte, Corine (2009) Les Chemins de verre. Les migrations des verriers d’Altare et de Venise (XVIe-XIXe siècles), chap. 7, Migrer et livrer ses secrets? Secrets et transmission technique, Rennes: Presses Universitaire de Rennes, p.201-238.
The first book dedicated to the “secrets” of glass-making was published in 1612 by the Italian priest Antonio Neri (p.202). Numerous authors during the 16th century had undertaken to reveal the secrets of several industries, in particular metallurgy but alchemy (p.203). These books had theoretically the ability to go beyond the usual oral father-to-son or master-to-apprentice transmission of techniques (p.206).
It is likely that besides the published books several manuscripts containing recipes used to circulate amongst the artisans, thus spreading best practice. Foreign editions of Neri’s book were rare; overall (p.207). Moreover those interested in Neri’s book were overwhelmingly scientists interested in the theoretical aspect of his experiences rather than fellow glassmakers (p.208). The influence of print on the spread of techniques over Europe thus seems weak (p.211). This way of carrying information through the continent was second to transmission by migrant workers.
However this transmission was often difficult. The fame glassmakers from Venice and Altare carefully kept their trade secrets as it was the root of their monopolistic rent. A few royal manufactures were created during the mercantilist era (p.214), in Spain, France, Portugal and Piedmont. These manufactures attracted Italian glassmakers by granting them privileges in exchange of their work; the new comers were rarely asked to transmit their secrets to the locals(p.215).
Those migrant workers were few and usually very well paid. The author qualifies these men as “migrants de brioche” (cake migrants) who, as opposed to the “bread migrants”, move not for survival but for wealth (p.218). To justify their refusal to transmit their secrets, the Italian artisans invoke the interest of their natural prince, the trade secrets are not theirs but belong to the community they come from. The only way to break this relationship is for the country welcoming them to grant them its nationality.
The hosts were constantly trying to access those secrets, for instance by providing the glassmakers with a lot of alcohol (p.221). Gradually the situation evolved and the migrant worker became more of an inventor whose novel process was protected by a privilege granted by a foreign sovereign guarantying a monopolistic situation in exchange to a publication of his invention (p.225). Thus allowing further emulations based on this technique. In France, inventors quickly lost their monopole allowing a rapid growth of the industry (p.226).
Another source of dynamism is the encounter and the cross-insemination of glassmakers from different countries and with varied abilities. Those commonly occur in the new large production centers being set up by the states or private individuals (p.227). Commonly also exogamic marriages allow the diffusion of trade secrets beyond their original community; typically a poorer foreign artisan would incorporate a local family which would bring credit, infrastructure and the right to produce attached to the nationality (p.228). Symptom of the evolution, in the 18th century migrant glassmakers start to sign contracts swearing not to reveal their secrets (p.230).
On the other hand, migrant workers often bring back to their original region new techniques (p.233). Migration is a necessary source of diversity and dynamism in the lesser production centers such as Altara that cannot rely solely on endogenous emulation like the larger ones such as Murano. However, imitation can only go so far and the producers using newly imported techniques are usually less appreciated than the original ones (p.235).