Material matters! So do some other things that go into furled leader design.
Nylon thread stretches, while Mercerized Cotton and Polyester do not!
If the thread size use for the looping sequence, is too small, the furled leader cannot handle bulky flies, such as the "Stimulator you were using.
The butt end of the furled leader needs bulk, to successfully transfer the energy of the cast from the fly line to the furled leader.
3/0 thread = 210 denier
6/0 thread = 140 denier
8/0 thread = 70 denier
For my 7 weight fly lines (and larger), I use 210 denier thread. For my 5 & 6 weight fly lines, I use 140 denier thread. For my 3 & 4 weight fly lines I use 70 denier thread.
I do not use nylon thread, I always use either Mercerized Cotton and Polyester thread. I do not use fly tying thread, instead I use "
Coats & Clark" or something similar.
One aspect that some furled leaders are missing is the coating. The original silk fly lines were braided around a center core of thread. The braided silk fly line was then dipped in shellac to bond the core and braidings. The line’s surface was also sealed with a coating of shellac applied using a cloth wrap dampened with Shellac.
The Shellac, helps to give the line a spine, and also seals the thread to prevent the knotting of the line. Same applies to furled leaders. I use warmed varnish for my dip, and wipe-down.
Another reason for all the “Wind Knots” is either your timing in casting, or the furled leader is not balanced with the fly that you are using. Either by weight or wind drag. Same applies for Wet Flies, and Streamer that soak up water, which add to their weight. The fly may be too much for the furled leader to handle.
Another problem with any leader construction is the hinge effect, if segments are not balanced, in relation to each other. You cannot just randomly place pegs in the leader board and start wrapping loops. Most of the leader recipes I have seen, are completely out of balance, and it is a wonder that they caster can get a decent cast of the fly onto the water.
There is a lot that goes into leaders, and fly lines, and fly rods. And the weak link will cause a angler lots of problems. ~Parnelli