Choosing a seal material for Shellac
The table above rates every common O-ring elastomer for service in Shellac on an A–D scale. A is Excellent, B is Good, C is Fair (test before relying on it), and D is Not Recommended. An X indicates insufficient published data.
For Shellac, the strongest candidates are Fluorocarbon (Viton), Perfluoroelastomer, Ethylene Propylene, Silicone, Fluorosilicone, Neoprene (Chloroprene), Natural Rubber, Styrene Butadiene, Butyl. These ratings are representative at ambient conditions (~20°C). Compatibility shifts with temperature, concentration, pressure and exposure time, so always validate the material against your real operating envelope before committing to a design.
