Background: Ideologies are socially constructed frameworks for sensemaking that influence teaching and learning. Drawing on Learning Sciences research on ideologies, we explore how an elementary science professional development (PD) community used substrate (shared interactional resources) in sensemaking interactions to reify or rearticulate dominant ideologies. Method: We analyzed PD interactions to understand how PD community members used substrate across multiple timescales as part of ideological sensemaking. Findings: We first show how participants drew on substrate to rearticulate ideologies about young learners' capabilities in science. We then show how limited resources available in substrate impeded interactional engagement with deficit narratives of multilingual learners. Contribution: Practically, we demonstrate how ideological rearticulation requires establishing intentionally designed substrate as a resource for later PD and facilitation that surfaces and challenges dominant ideologies. Methodologically, we show how substrate--often analyzed at microgenetic scales--can be traced back over longer timescales to understand longitudinal learning.