Herder chef's knife K5 HRC 60 blue pierced

The Windmill knives from Robert Herder in Solingen are justly known for their carbon steel component of at least 75% and a hardness grade of at least 56 HRC for the carbon steels. They stand out for their traditional sharpening technique: Windmill knives are sharpened to an extreme thinness. The result is an astounding cutting experience.
The most time consuming type of sharpening is the Kessel’s bulge grinding, a special kind of thin grinding in which the blade is taper sharpened from the blade to the back of the knife.

Glazing is what one calls in Solingen the smoothing out of grinding scores remaining on the blade, or the final grinding. The most time-consuming step of the glazing technique is blue glazing, whereby the steel is ground finer and finer in several stages. A blade that has been blue glazed has a slight blue hue.

The elastic blades of the following knife has received the Solingen final grinding and is blue glazed. Owing to the very high Rockwell grade (HRC) of 60 it retains its sharpness much longer.

Because of their high degree of hardness and extreme thinness due to sharpening, the blades should never be twisted or turned. Under certain circumstances this can lead to ruptures in the material.

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

Pließten is the name given in Solingen to the smoothing of the grinding grooves remaining on the blade, i.e. the fine grinding. The most complex stage of this technique is blue finishing. In this process, the steel is ground finer step by step. That a blade is blugepließtet, you can tell by the fact that it reflects in the light slightly bluish.

The elastic blades of the blue-plated knives from Herder are ground in the Solingen thin grinding as well as in the whale grinding. Thanks to the very high hardness of 60 Rockwell (HRC) they keep their sharpness much longer.

Because of the high hardness - and because they are ground so exceedingly thin - the blades should not be turned or even canted, as this may lead to chipping on the material when cutting.

The traditional material for knife blades is carbon steel. This is not stainless, but with a fine-grained structure it can be hardened to a particularly high degree and made extremely sharp. The higher the carbon content, the higher the hardening capacity. These knives owe their high cutting ability to the material in addition to the finishing, and their high cutting edge retention to a material-related self-sharpening effect. Each time a cut is made through fruit or vegetables, a minimal amount of material is removed and the blade wears evenly. The knifemaker refers to this as micro-corrosion. In fact, this means that the blade becomes steadily narrower over the years - but always retains its sharp grinding angle. Blades made of carbon steel put on a dark patina over time, but this in no way negatively affects their quality, but on the contrary gives them better protection against corrosion.

Carbon steel knives do not belong in the dishwasher. Wipe the knives dry after rinsing and occasionally apply some blade oil. Discoloration may occur on the blade material. However, this is not a sign of inferior quality, but only indicates the rather high carbon content in the material. In case of flash rust, the use of the rust eraser is recommended. A resharpening can be done with the sharpening steel.