Semperfli Dry Fly Poly Yarn

With a very specific gravity / density of 0.91g/cm3 polypropylene yarn including Dry Fly Polyyarn Caddis Brown is lighter than water which means that it floats making it ideal for dry flies. 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.