A Schlappen feather is a transitional feather found between the saddle and the tail of a rooster. Unlike a tail feather, the rachis or shaft is narrow like a saddle feather. Unlike a saddle feather, it is all web, like a tail feather. The length of a Schlappen feather and its barbs vary greatly, but are especially useful on larger flies.
Schlappen is purchased usually strung and dyed in an array of colors, but it is also available in a natural off‑white color for your personal dyeing pleasure. Some strings will have feathers fairly long and gradually tapered while some will be 2" to 3" shorter with typically rounded tips. In either, you will find feathers of different taper, some variance in the amount of web and a variety of barb lengths.
Some Schlappen feathers have stems that are objectionably large to wrap. Save those feathers for false‑hackled hair‑wings, streamers and wet flies. Additionally, Schlappen feathers can be useful in a variety of both freshwater and saltwater flies.
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