This page is a version of a couple of similar articles that I wrote back in the late 1990s. I really like Diffusion Hackling for a variety of patterns, and I’m sure that some of my European friends will recognize the technique immediately (since I learned it via a European). If you tie, this one is worth knowing.
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Diffusion Hackling is not hackling in the usual sense, such as winding a material like a feather around a hook or a parachute post to produce legs and/or wings. Rather, Diffusion Hackling splays (or diffuses) materials to achieve very interesting effects.
Originally, this technique was a method for “parachuting” deer hair that was shown to my father (and then to me) by Charles Jardine years ago. After some experimentation with a wide variety of materials, I started referring to it as “Diffusion Hackling” (it likely goes by other names elsewhere). Here’s how it works:
Tie in a parachute-style post of almost any material at the rear of the thoracic region (the post could be foam, deer hair, chenille, poly yarn, Z-lon, or whatever). Do not reinforce the base of the post with thread. This is Post #1 and it will make the top of the thorax.
Then, tie in another post of fibrous material directly in front of the first post (this material will make the “hackle”). By directly, I mean the posts should be right up against each other. This second post is Post #2. Ideally, Post #2 should be the same length as the legs and/or outspread wings of the insect. This is especially important when working with materials that you wouldn’t want to cut to length after tying them in (like deer hair tips). If you want a thorax, dub it or wind it on at this point. With me so far? Okay then, here it comes:
To make the hackle, pull Post #1 forward through Post #2. Post #2 will (or should) diffuse out to both sides, creating a flat hackle. Using a fibrous material for Post #1 may require that you twist the post before pulling it forward. The twisting makes Post #1 more or less solid, thus preventing materials in Post #2 from slipping through it. In addition, using softer materials for Post #2 may require that you render some assistance to get a good diffusion. Tie Post #1 down just behind the hook eye, being sure not to trap any material from Post #2.
I typically clip post #1 so the end extends over the hook eye. You want a quick wing? Make Post #1 long enough to fold back over the thorax, and then lash it down just behind the eye. Trim Post #1 to length/shape (the length/shape of a mayfly wing, for example).
Diffusion Hackling can be used for a variety of flies in a variety of sizes and styes. Because of its versatility, I find Diffusion Hackling to be a “must-have” technique in my tying repertoire.Do you find that a picture is worth a thousand words? Then here you go: