Stainless steels for cutlery have a tendency to spot after use in salt water. All stainless steel knives need a rinse in fresh water after use. Dry after use and apply a thin layer of silicone grease or paraffin to prevent the formation of surface oxides. Any oxidation stain can be easily removed with a common ink eraser.
Abrasive treatments are strongly not recommended: would damage the special surface treatment.

Sharpening
The knife comes sharpened and must be maintained as such in order to function properly and safely.
To perform a good cold-grinding, place the blade with at 25° angle to the stone.
The serrated edge can be revived only by a special tool.