No no. Zelon floats well. The best part is how quickly it dries off. After you catch a fish you swish it off, snap cast it once or twice and away it goes. You don't have to spend five minutes shaking it with powders they way you do with CDC.
What's that stuff. There is another synthetic that mats up and sinks but Zelon isn't it. Antron antron antron. Antron is not much good for dry flies but Zelon is.
Zelon is a discontinued carpet fiber. It takes dyes after manufacturing, which is great for fly tiers and bad for rug makers, because spilled wine ruins the rug. That's why they don't make it anymore. Once the Zelon is gone it's gone forever. It's not clear how much longer it will be available.
Carpet fibers that are not Zelon make good dry fly hackles too. But you do have to find it already manufactured in the color you want, which is hard. I browse free carpet samples at Lowe's and Home Despot a lot. I make lots of dry flies with carpet scraps too.
Here's an Enhanced Comparadun -- made with a sparse bit of clear, semi-transparent Zelon underneath. The Zelon disappears as it drifts. But it does give the fly some added flotation moxey.
Craig Matthews'
Sparkle Dun is a Comparadun with a Zelon tail that might look vaguely like a not-yet-shed nymphal skin, that also (and more importantly) makes the fly float better. A lot better. Zelon is good stuff.
Now I'll have to make an Enhanced Sparkle Dun.