Life science research is continuously engaged in exploring, measuring, or limiting potentials for life. The concept of potentiality pervades practices surrounding cells, bodies, and technologies. Based on an ethnographic study of how couples in fertility treatment become donors of embryos to human embryonic stem cell (hESC) research in Denmark, I explore ways of measuring and talking about the potentiality of embryos in the fertility clinic and in interviews with donors in their homes. In the fertility clinic, the embryo suggested for donation to hESC research is defined as waste that cannot be used and therefore is suggested to be put in the bin. The “bin,” thereby, becomes a dominant conceptual framework for claiming the embryo's nonpotentiality as a biographical life and for making the embryo for donation emerge as a blank figure, the essentially undefined and undetermined element that has potential to take on any identity but, as yet, has no specific determination. When further exploring how the in vitro fertilization (IVF) couples relate to the potentiality of donated embryos, I argue that the embryo suggested for donation is not experienced as completely blank: traces remain of the embryo's former identity as a possible biographical life related to its “parents.” To make the embryo blanker—indeed, safely blank—it becomes imperative for the couples to set up boundaries to eliminate the possibility of an unwanted return. Drawing on rubbish theory, kinship theory, and Michel Serres's concept of the blank figure, I draw attention to the boundary work as well as the trace effects expressed in articulations of potentiality.