This presentation was given during the WiNoDa winter school, a five-day intensive course on the topic of Research with Natural Science Collections. Data, Quality, and Methods from 24-28 November 2025. Organization: German Federation for Biological Data e.V. (GFBio) with support from the Museum für Naturkunde Berlin (MfN), German Archaeological Institute (DAI), Vernetzungs- und Kompetenzstelle Open Access Brandenburg (VuK). Abstract: This session is intended to deepen the learnings from the previous session (10.5281/zenodo.14918374) on OpenRefine and to strengthen confident application through practice. Focus will be laid on string transformations using GREL functions and regular expressions. Please make sure that OpenRefine is installed and a project with data is available. A training dataset with uncleaned data from a Zooniverse transcription project can be downloaded for training purposes from https://doi.org/10.5281/zenodo.17429281.