Working with dyes almost always produces picturesque results. Maarten van Meerbeek, an organic chemist in the Interventional Molecular Imaging group at Leiden University Medical Centre, has experienced this regularly in a project using Cy5 dyes. The picture shows one of the building blocks for new intraoperative tracers in a flask. The final tracers required a further series of modifications. Once synthesised, the substances could potentially be used in image-guided surgery. Van Meerbeek occasionally posts photos of his experiments on his Instagram stories: @creek_dnb