This paper analyses how talk between researchers and their volunteer human subjects works to construct a safe and supportive environment in a laboratory setting where women volunteers participate in the development of a new imaging technology with potential for diagnosing breast cancer. Drawing on discourse analysis perspectives, we explore the work talk has to do in order to facilitate the instrumental, ethical and social dimensions of the interaction between researchers, volunteers and technology. An important cross-cutting theme is the use of various discursive strategies by both researchers and volunteers to manage perceptions of risk and construct a safe research environment, which will foster the active cooperation from volunteers necessary to achieve successful research outcomes. We draw attention to the interactive and two-way character of the technology talk observed in our research setting and how it co-produces researchers, volunteer subjects and the technology and supports the working social relationship between them that is vital to success.