Above Photo: A #20 Kapok Hen tip wing Baetis tied as a baseline test for  Semperfli 18/0 Nano Silk. Semperfli Nano Silk passes with flying colors and outshines  all other GSP threads for micropatterns. So Gel-Spun Polyethylene, or GSP, is a very high-strength, low-bulk thread, and at 18/0, it is literally the ultimate go-to thread for my micropatterns. Off the bobbin, this thread seems wispy and unmanageable, but on the bobbin, it's a pleasure to tie extremely tiny flies with. Unlike other floss-like threads, this gel-spun fiber requires a ceramic bobbin; otherwise, it tends to get hung up and fray. Spinning the thread clockwise will bind the fibers if you choose to do so. Creating low-bulk dubbing loops for size 20 flies and smaller is not a problem. I have found that Kapok fibers and this thread are an outstanding combination for dubbing tight micropatterns. Kapok mingles very well with this GSP thread. If you mix the Kapok (which acts as a binder for other dubbing m...