Strip the flues from a portion of the herl; the amount is something you have to find by trial and error. For this particular width of herl and size of hook it worked out to be about 3/4" (19mm).

I simply use my thumbnail to strip the flues. A lot of tyers find it difficult and use razor blades, pencil erasers and even "burn" them off with bleach ... whatever works for you.

The flues dissappear quickly.