
Nicknamed by fly tyers world wide the 'floating yarn'. With a very specific gravity / density of 0.91g/cm3 polypropylene yarn is lighter than water which means that it floats making it ideal for dry flies, most commonly used as parachute posts, and dubbing.
Many companies claim to use polypropylene yarn however a simple test you can do at home to check if it is genuine polypropylene yarn is to cut a 1 inch / 25mm strip, scrunch it up in your fingers and drop it into a glass of water. If it is genuine polypropylene yarn then it should dip below the surface and then return to the surface. Indeed leave it for a day and it should still be floating as it is lighter than water and it is this property which makes it very, very special for dry flies.
There are a few fly tying polyyarns on the market today from different companies. Indeed Semperfli makes two versions of polyyarn - the original Semperfli Polyyarn that comes on cards and is ideal for posts and wings and the new Dry Fly Polyyarn, a product on a spool which is intended for body and wings of flies or to create detached bodies
