It is the Anti Rust coating, applied to the griddle in the factory. It is important to remove this, using detergent, before first use.
External surfaces should be cleaned regularly with hot water, some soap and a soft sponge. Rinse your contact grill with a moist sponge.
Spare parts for Dualit contact grills can be obtained by calling Dualit Customer Service on 01293 652500. (UK customers only)