We study the marketing of radioactive products in Sweden from 1910 to 1940, using a dataset of newspaper and magazine advertisements. We use multimodal critical discourse analysis to show how marketers harnessed the meaning potentials of language and semiotic resources to embed radium in discourses of science and technological development, and thus convince consumers of its health benefits. We find that canny marketers continuously colonized, shaped, and remarketed radioactive products in response to greater scientific knowledge and growing safety concerns. These techniques highlight the challenges of distinguishing legitimate/illegitimate applications of discoveries when science and entrepreneurialism move at the same pace.