CDC
Paul Prentiss

The description "Cul de Canard" was reputedly coined in the late 1950s by French tier Henry Bresson for one of his patterns.

Information about CDC feathers started to appear in the US fly fishing media during the early 1990's. Its use in Europe dates back to the 1920's, primarily in the region between France and Switzerland. In 1980 Marjan Fratnik, a tier from Slovenia, designed the F Fly which generated renewed and expanded interest for various CDC patterns by European tiers. Gerhard Laible, Hans van Klinken, and Marc Petitjean further popularized the use of the feathers in a series of innovative designs.

The first time I heard about CDC was in Darrel Martin's Fly-Tying Methods (1987). I really didn't pay much attention to it until René Harrop wrote an article for "Fly Fisherman" in 1991. Its publication brought the material to the attention of the majority of US tiers.

Recently, Hans Weilenmann, a well-known Dutch fly fisherman and fly tyer from Amstelveen, The Netherlands, published a highly regarded article about
CDC in "Fly Fisherman" magazine in March 2003: click here for the complete article. His signature fly developed in 1992 is the CDC&Elk - a great searching pattern for various insects the world over.

 [Click here for a 5-minute Windows Media video (12 MB) by Hans Weilenmann showing step-by-step how to tie the CDC&Elk. You must have Windows Media installed and have a broadband connection to the Internet to view this video]

With his permission I have included the tying tips and tricks section of his magazine article and picture and recipe for the Snow Flake, which I think you'll find of considerable interest. If you have not visited his web site that includes a wide range of great patterns from the best tiers in the world you are really missing the boat - click here

 

Tips and Tricks with CDC

Bleaching - Bleaching natural dun-colored CDC feathers in a mixture of equal amounts of 3 percent hydrogen peroxide and household ammonia results in a wonderful, warm, light-amber color. The timing is not critical and may range from several hours to an overnight soak. Rinse the feathers in fresh water and let them air dry. The resultant feather stem remains pliant and the bleaching process appears to leave the feather structure mostly intact. The hydrogen peroxide and ammonia mixture gives off unpleasant and unhealthy fumes, so do this in a well-ventilated area.

Dubbing - Barbs broken away from the stem make nice dubbing material. Use them alone or mix in other natural fur or synthetic dubbing.

Bodies - Roll a Type 2 feather on a sheet of firm foam. Press the feather down with your fingertips and roll perpendicular to the stem. Start from the butt and work up toward the tip. Once you form the "rope," you can tie it in by the tip and wrap it around the shank for a buoyant and naturally tapered body. Many of Marc Petitjean's patterns feature this style of body. Including the stem makes these bodies virtually bulletproof, without the need of a reinforcing rib.

Trimming - When you cut CDC with scissors, you get an unnatural-looking square edge. "Tear away" the excess length of the barbs for ends that resemble the natural tips.

Drying - I prefer to dry my CDC patterns using amadou. I have experimented with other drying agents such as Shimazaki Dry Shake and Frog's Fanny, but it appears that once you use either of the two on a pattern, the buoyancy only lasts one fish before the drying agents need to be reapplied. Flies dried with amadou can be fluffed up by blowing air on them or with several false casts.

 
Snowflake Dun
Pattern: Roman Moser, Fly and photograph: Hans Weilenmann
 


Hook: Tiemco 102Y #13-#17 (or equivalent fine wire hook)
Thread: Brown or White 8/0
Tail: Fairly sparse CDC clump (Type 3), half to three quarter shank length
Body: Dubbing to match the natural
Outriggers: Hackle fibers (see instructions)
Wing: Double layer of CDC (Type 2, see instructions)
Head: Fine white poly yarn. I use a very fine poly yarn called siliconized polypropylene

(The materials are listed in the order in which they are tied. Instructions assume right-handed tier.)

Tying instructions:

1. Run the thread down the shank and tie in a fairly short CDC tail.
2. Apply dubbing to thread and make a thin, somewhat tapered body, ending a bit short of the eye.
3. Prepare a hackle, fiber length just short of shank length, as follows:- Sneak in with the tip of your scissors and cut the stem half an inch from the tip- You should now have a hackle which ends in a 'V'- Leaving the top 4-5 fibers (on each side), stroke down the remaining fibers
4. Shiny side up, straddle the hook with the 'V', the fibers angling some 30 degrees down and towards the bend of the hook.
5. Holding the 'V' in place with your left index finger and thumb, tie them down with a few tight turns of thread. Trim remainder of hackle. You should now have 4-5 fibers on either side of the shank, which will act as outriggers, stabilizing the fly. (By trimming the top bit of the stem only, you can prepare the hackle for the next fly)
6. Take two CDC feathers and line up the tips. Tie in a wing, sloping back over the body. Similar to, but not quite as long as a caddis wing. Trim excess. (Or in economy mode: Take a large CDC feather and bunch up the tip. Tie in a wing, sloping back over the body. Similar to, but not quite as long as a caddis wing. Trim excess. Snip away the tip of the stem from the leftover CDC feather, bunch up the tips again and tie in again, effectively doubling the number of CDC barbules in the wing. Trim excess.)
7. Take a short piece (about 0.25") of fine white polypropylene yarn. (Split the yarn first, if too bulky for the size of fly) Tie in the piece of yarn in the middle on top of the wing, the other half overhanging the eye with two or three firm wraps. Next fold back this half and tie down. Complete the fly with a whip finish and a drop of varnish.

This is a Roman Moser pattern. Roman grew up in Gmunden, Austria, where he fished one of the best known trout and grayling rivers in Europe, the Gmundener Traun.

The Snowflake Dun is a low riding mayfly imitation. The white poly near the head provides both the origin to the name and a focal point when fishing it.