Fifty Fly Fishing Tips: #36 — Dry flies and flotation — Building in some buoyancy and preserving it

by | Apr 2, 2018 | 10 comments

Hatch season is just around the corner. On some rivers we’ve already experienced good fishing over eager trout rising to delicate Blue Winged Olives. And somewhere in the distance, a chorus grows louder — the Grannoms are coming, the Grannoms are coming.

Oh sure, there are midge fishing opportunities around here all winter long. (I know a local guy who travels in shorts and picks his spots from the banks with no-see-um dry flies all winter long). But for most of us, the winter season is a subsurface fishing affair — we bottom bounce nymphs and strip streamers for eligible trout. And after four months of all that, I don’t know anyone who doesn’t get excited about a good dry fly opportunity. In fact, show me a legit chance to fish dries for active fish, and I’ll take it any day of the year.

And now, on the precipice of all the major hatches, right before mayflies, caddis, midges and stones start bumping into each other, we prepare at our vises. We tie flies, and we dream. We pack our gear and envision the surface slash, the gulp, the dimple and the ring of the rise. So it helps to consider for a moment — what keeps a dry fly floating on the surface in the first place?


Buoyancy is all about trapped air. It’s what keeps an eight-hundred foot cargo carrier afloat at sea, and it’s what floats a #24 Trico Spinner. With just enough trapped air to overcome the weight of the hook and material, the fly floats on the surface and resist being pulled underneath and drowned. It’s simple.

Regarding this buoyancy, we must consider two things: the materials of a fly (what actually traps and holds the air), and a way to preserve the material’s ability to hold air (waterproofing).

Let’s tackle both.

Material Buoyancy

This article is not a comprehensive list of materials that keep flies afloat. But here’s an index of the buoyant materials that lie in the cedar-scented drawers of my own tying desk: foam, hackle, hair, CDC, snowshoe rabbit’s foot and yarn.

It helps to recognize the strengths and weaknesses of each material.

Foam, for example, floats all day with very little treatment, but it’s a material with no motion. So most flies incorporating foam also utilize other materials that provide motion to a fly.

Hackle, on the other hand, moves. And that motion gives the impression of life. The barbules of good, stiff hackle, wrapped and stacked against each other, trap air next to the fly and hold the river at bay. I often over-wrap parachute style flies which I plan to use as suspenders in a dry dropper rig. Because the extra wraps trap more air, the fly can support more weight. But even the best hackle needs maintenance to sustain its buoyancy, so we dry and treat the hackle.

Hans Weilenmann’s Sledgehammer. Damn right.

Elk, moose and deer hair wings and tails are common on dry flies. Because good hair is semi-hollow, it carries built-in flotation with each strand. Elk and deer hair also have a natural sheen and water repellency, allowing them to shed excess moisture on a swift backcast. Not all elk or deer hair is suitable for dry flies, and once you tie about a thousand Comparaduns you’re cursed into the struggle of finding exactly what you’re looking for until the end of days.

I’ve bought and tied with just about every poly, hi-vis, extra-floaty-fly-tying stuff that comes on a card or in a tiny bag. All of these yarns float to some degree — the buzzword now is hydrophobic. That sounds really great, and it probably is. But the most important thing I’ve found for a dry fly yarn is crinkles. I want a yarn whose strands are not straight, but squiggled. When laid out and bunched together, all of those crinkles trap air and do what we want — they float a fly. My preferred yarn for parachute posts, Dorsey Yarn Indicators, and any other yarn used for flotation is Macrame Cord, specifically, the 6mm polypropylene cord sold by Carol’s Rugs. It’s hydrophobic!

While polypropylene is completely synthetic, you can’t get much more natural than the feathers plucked from a duck’s butt. Enter CDC. As years pass I use more CDC, mostly because the trout tell me to. Wet or dry, it has a remarkable ability to imitate life. And that motion — that impression — catches fish. It’s like the dry fly equivalent of marabou.

CDC is a great option for subsurface patterns also, but when kept dry, a good CDC fly rides on the surface, with some of the fibers undulating around the fly and more fibers swirling in the surface. Two of my favorite styles are the CDC and Elk, and the Puffy. I love simple flies.

But CDC requires a lot of maintenance . . .

Among this list of buoyant material options, you’ll notice that more movement comes with more maintenance. Foam rides high for a very long time. Hair wings are similar. Stiff hackle and good yarn ride high only until water penetrates into the small air chambers. And CDC needs to be refreshed at regular intervals.

With more movement comes more maintenance.

Olive Puffies. Simple and convincing as an emerger, dry or spinner.

Preserving Buoyancy

To keep dry materials repelling water and riding high, the modern fly fisher has a few options that your grandfather did not.

Let’s quickly break the floatants into three categories: paste, gel and powder.

Paste is the thickest option. It can overwhelm a small and delicate fly, but it’s perfect for floating large or bushy dry flies. Paste is also a great match for foam. Once applied, a paste treatment lasts longer than gel or powder. My favorite paste floatant is Silicone Mucilin in the green can.

Gel is the floatant I use most. For standard dries, Comparaduns, Parachutes, Klinkhammers, hairwings, spinners and many midges, a small drop of gel goes a long way. Work it into the fibers of the fly and start casting. Without a good floatant, many dries quickly become waterlogged. But protected with floatant, any gained water in the fly is often ejected on the backcast. Some gels are more temperature sensitive than other. I like Loon Aquel, because it’s always the same consistency — it’s not too runny in the heat and doesn’t become sludgy in the cold.

I first bought desiccant powder to use with CDC, and now I use it for many dry fly styles. (Don’t use paste or gel on a CDC fly). When the fly is wet, dry it on a rag, and then apply powder with a brush or in a shaker. The desiccant is remarkably effective at pulling out excess water. Some of the powder clings to the fibers of the fly and protects it for a little while. Really, nothing rides higher than a freshly desiccant-treated dry fly. It’s as if the fly barely touches the water.

Frog’s Fanny was the first big hit on the market for powdered desiccant, and now every fly shop seems to have their own branded version. No wonder, really, because you can buy the stuff in bulk — quart containers. It’s just ground up silica, afterall.


Last thing: Many years ago, a friend told me how he worked a drop or two of Rain-X into every dry fly he tied at the vise (not the CDC flies). Once I tried it, I’ve done the same ever since. Allow the Rain-X to dry, then store the fly in your box. Often, a fly pre-treated this way needs no other dressing — it will float high for a very long time.

And we’ll all float on, okay

Nothing’s worse that a sinking dry fly. Sure, some flies do very well when riding in the surface or just beneath, but if we intend for the fly to be on the surface, that’s where it should stay.

It’s necessary to balance movement and motion — natural buoyancy with the impression of life — how much you want to fiddle with pastes, gels and powers with how high and how long you want the fly riding on the surface.

Really, try everything and you’ll find your own preferences.

The days are short, but the life is long.

Fish hard, friends.


Enjoy the day.
Domenick Swentosky


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Domenick Swentosky

Central Pennsylvania

Hi. I’m a father of two young boys, a husband, author, fly fishing guide and a musician. I fish for wild brown trout in the cool limestone waters of Central Pennsylvania year round. This is my home, and I love it. Friends. Family. And the river.

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  1. Never heard of using Rain-X. I guess I figured it would add some weird scent to the fly. I’ve always wondered how much scent actually goes on a fly. I know Trevor from Fly-Carpin has mentioned going so far as to boil his flies to kill any sign of scent. That seems like way over kill but it works for him.

    • Personally, I don’t think scent matters much for a trout fly. I agree that it matters a lot to carp, but they feed differently and in different areas that trout (usually). I don’t believe trout hunt by scent very much.

      That said, Rain-X dries with almost no scent.

      Just my thought. Cheers.

  2. Dom,
    I was with you all the way until the end.
    I have used a product by Hareline Dubbin called Watershed.
    Now you have me wondering if it’s nothing more than Rain X
    in a fancy 1 oz bottle.
    No ingredients listed so a smell test is in order.
    …and I like Diddies too.

    • Hey Rick, I used Watershed too. After the bottle ran out, I did the Rain-X. I notice no difference. They both really help materials float.

  3. There is one other key factor that keeps dry flies afloat: surface tension. Water repellent (hydrophobic) pastes, gels, spray treatments, and powders all prevent the breaking of the extra-strong, elastic-like surface tension bonds that form at the water-air interface. Try this visually entertaining home experiment to prove the point: Fill a drinking glass with cold water and gently place a small dry fly so that it floats on the surface. Now, place a drop of dishwashing detergent on the tip of a butter knife and gently transfer the detergent to the surface of the water . The detergent will instantly break the surface tension and you can watch in wonder as your fly instantly loses the support force that had kept it floating!

  4. Great tips, as always. I agree with you that movement is a frequently overlooked aspect of dry flies. To wit, something to think about is using soft hackles on dry flies. Properly treated, they float rather well, and they impart a lot of movement. For example, a simple fly would have a tail, fur body, CDC wings, and a sparse collar of soft hackle.

  5. Once again, another succinct and excellent post. New to tying and been tying the nymphs. After witnessing a rare mayfly hatch here on our southern mountain waters, I’m now exploring dry tying. The perspective provided here is extremely helpful. Thanks.


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