With the so-called Buckelsklinge this knife is manufactured since 1872, the founding year of the company Robert Herder.

The Windmühlen knives from Robert Herder in Solingen are remarkable not only because of the knife steel (at least 0.75% carbon content and a hardness of at least 56 HRC for the carbon steels), but above all because of the craftsmanship, which spares none of the traditional grinding efforts: Windmühlen knives are ground extremely thin. This results in their astonishing cutting ability, which is an experience in use. The most elaborate type of sharpening is fuller grinding, a special type of thin grinding in which the blade is tapered towards the back of the knife.

In Solingen, the process of smoothing the grinding grooves remaining on the blade is known as flattening, i.e. fine grinding. The most complex stage of this technique is blue polishing. The steel is ground finer step by step. You can tell that a blade is blue-fluted because it reflects slightly blue in the light.

The elastic blades of the blue-blued knives from Herder are ground using the Solingen thin grind and fuller's edge. Thanks to the very high hardness of 60 Rockwell (HRC), they keep their sharpness significantly longer. However: Due to the high hardness - and precisely because they are ground so extremely thin - the blades should not be twisted or even tilted, as this can lead to chipping of the material when cutting.