This patent sets out a method of sealing and packaging plastics with RF fields. Dielectric loss in plastics (such as the ones used in ready meal packs) provides a cost effective and rapid method for heating the material. This is the first application of RF welding to food packaging. This work was conducted in conjunction with an SME, Stanelco PLC, that designs food packaging equipment for large chains such as ASDA and Walmart and this company financed the patent. RAE_import_type : Patent / published patent application RAE_uoa_type : General Engineering