International audience While there is a wealth of research on the history, philosophy and epistemology of economics, few studies approach economics as a practical and material endeavour in the way STS and ethnographies of science have approached natural sciences. To explore how objectivity is practically accomplished in laboratory economic experiments, we focus on a, at the face of it, modest and mundane thing: the written instructions that guide experimental subjects in the lab. In a material-semiotic perspective, these instructions can be understood as text-devices. We follow this text-device 'on the move' from its very writing, through the lab, the review process and out into the journal article. To do so, we analyse "text-author ensembles": journal articles together with practice-oriented interviews with their authors. We show that the instructions act not simply as a text, but as an experimental instrument that also performs the procedure of experimental economics. They draw together the procedural, material and rhetorical dimensions of experimental work in economics, and link the lab setting to collective validation procedures within the discipline of economics. To achieve this, experimental economists rely on qualitative writing skills refined in collective writing and reviewing practices. This particular text-device 'on the move' alert us not only to the role of writing and writing skills in the production of scientific knowledge, but to the role of texts as material and semiotic objects that can produce not only facts, but labs and disciplines too, and that are key to the accomplishment of objectivity in experimental economics.