Especially with blades made of carbon steel, the typical dark spots as well as rust can appear after some time. This is absolutely normal and does not represent a defect, but it may disturb the optical appearance of the knife. To give the blades a new shine again, regular care with the Boker Super Eraser is therefore recommended. Thanks to the 240 grit, the universal abrasive cleaner is perfect for grinding, scrubbing, smoothing, cleaning and polishing metal surfaces. Made in Germany.