Effective sealing of glass jars used in natural history wet collections is critical for long-term specimen preservation. The selection of an appropriate sealant is a long-known challenge in wet collections management. For a new permanent exhibition at the Croatian Natural History Museum, we decided to use ground-glass-stopper jars, but faced limited time at the outset of the project to select a suitable sealant. We therefore compared nine different sealants that included silicone, wax-based sealants, as well as several commercially available greases and rubbers. Our evaluation focused on key criteria relevant to long-term exhibition use: aesthetic appearance, handling properties and sealing performance. Based on its advantages over the other sealants and its established use in other wet collections, we selected the beeswax–colophony mixture to seal exhibition jars. Although highly effective, this sealant requires skill and is relatively time-consuming to apply. Therefore, we refined the application protocol for the commercial beeswax–colophony mixture, which will serve as practice-based guidance for sealing glass jars and cylinders with ground-glass stoppers. Our comparative assessment also offers practical guidance for curators and collection managers seeking appropriate sealants for exhibition purposes.