Windmuehlenmesser or Windmill knives are a brand of Robert Herder GmbH & Co. KG in Solingen Germany. Solingen is a world famous center for outstanding craftmanship of high quality knives.
Solingen "dry-fine grinding"
In contrast to most knives today, "Windmill" knives are still produced according to the "Solingen dry-fine-grinding" technique.
The grinding angle is much farther up on the blade than is customary today. The blade is dry-fine-ground and tapers to a thin, very sharp cutting edge. Knives ground in this way are defined by their special sharpness and long lasting cutting edge.
These blades are not designed for levering or canted cutting and they should not be used on hard chopping boards. They can be resharpened with just 2 or 3 strokes over a grinding steel (not 10 strokes or more as usual today).
Glazing and Blue Glazing
"Glazing" is a special process of fine grinding the blade. At different stages, the blade surface is "fine-glazed" and then "blue glazed".
Since time immemorial, these processes have formed part of the most time consuming of the traditional Solingen grinding techniques, "blue glazing" being the finest processing of the blade surface.
Typical for this kind of blade are the bluish to rainbow coloured shimmers of the fine grinding marks. This work is done by Master Grinder W. Fehrekampf. One of the last true master grinders today who is skilled in the fine art of "blue-glazed" knives, he is now passing on his skills to young grinders.
Care of Wooden Handles
DO NOT clean your Windmill knives with a wood handle in washing up water. They are also not suitable for dishwashers. This would bleach and dry out the wood. The best cleaning method is under a running tap, holding the point of the blade downwards.
The types of wood used need a certain amount of care. They come from Germany and Europe and given the climate there they do not grow as densely as e.g. wood from tropical forests. This also means that they are not completely water resistant but they do have a very beautiful, unique grain.
The grain and the different shades of colour are accentuated even more if you apply a natural wood care oil like macadamia nut oil. This oil is absorbed quickly, providing optimum protection and care.
Here is a video about Windmill knives but only in German: