A classic modern material. Poly-yarn has a few tying uses, providing us with posts on parachute-hackled dries is by far the most important. I’ve used it for spinner wings, tails and as a body material too.
This form of polyproylene is low density, so it floats, it is also non-absorbent, self-coloured and extremely tough – huge floating polypropylene ropes are used to hold large ships at dock. These samples are obviously black and white, the colour is manufactured into the plastic, as far as I know this stuff cannot be dyed – white yarn can be marked with indelible marker pens, which lasts for a while.
As is typical with white poly-yarn this is very white and the black is jet black. White is by far the most popular post colour, both are very visible on water, black is surprisingly visible. The yarn in these samples is typical of the type, the gently glossy fibres have a degree of stiffness, soft enough to tie with but cut to a tuft they stand proudly. The fibres have a slightly ‘crinkled’ texture, which is deliberately manufactured into the product so the yarn has volume and when cut short it tends to flare out, yarn with dead straight fibres is much thinner and does not flare when tied in as a post.
The thickness or denier of the fibres looks and feels in the middle of the range, coarser fibres can make for very bulky flies, very fine fibres are OK on tiny flies, but not good on typical dry fly sizes where they lack the stiffness we want. I like that this is a single strand, single-ply yarn, makes tying a bit less tangled.