This article examines how the English and French patent regimes contributed to the formation of technological knowledge in the eighteenth and nineteenth centuries. From the 1730s in England and the 1790s in France, patent requests were required to include a textual and often visual specification of the invention claimed by the applicant. We study the evolution of the specification genre, the chain of actors involved in the production of such documents, and the circulation of these texts and drawings in the public sphere of technology. To do so, we draw on a case study of six pairs of patents in the lace and tulle industry. By focusing on patents taken out in both countries for the same invention, we analyze how local cultures of invention and legal regimes shaped how technology was described. Tracing the history of Technology understood as the science of industrial arts requires, we argue, a deep dive into the archives of practice.