Before we get started on thread differences, let's talk wax. Almost all tying thread comes from the factory waxed, and if you want unwaxed thread you'll have to use silk, GSP, Kevlar, or a specialty thread like unwaxed 3/0 Danville's Monocord. Waxed thread is not a substitute for dubbing wax, and is applied to the thread in the manufacturing process merely to keep the thread from fraying and unwinding wildly when it breaks. Size is another major source of confusion for many consumers. Historically, fly-tying thread was sized using the archaic aught system that came originally from sizing silk surgical sutures, and is still used today for that purpose. Using a zero as a baseline and additional zeros to denote smaller sizes, the aught number described relative size based on a range of diameters and worked nicely in an age of organic materials where exactness was not always possible. Many tying threads are still measured this way today, as an example, 000000 or 6/0 (six aught) being smaller than 000 or 3/0 (three aught) threaThe Danville Chenille Company used this system for tying thread for 50 years with no issues, but in the 1990s, UNI Products entered the tying market. While UNI also used the aught system to distinguish its larger and smaller threads, the company used a different baseline diameter, and that's where everything went to hell. Using the aught system, tiers assumed that the new 8/0 UNI-Thread was smaller than 6/0 Danville's. And 6/0 UNI-Thread seemed much stronger than 6/0 Danville's. Despite the numbers on the spool, those comparisons weren't fair because the two threads aren't the same size at all. Wapsi Fly Company moved away from the confusing and archaic aught system when it introduced UTC Ultra Thread, and used the thread industry denier standard of measurement. Denier is the weight, in grams, of 9,000 meters of thread. It's a physical actual weight for a length of thread. It says nothing of the thread configuration, material, or strength. UTC Ultra Thread comes in 70, 140, 210, and 280 deniers, and simplified thread sizing to a significant degree. It's pretty simple math to figure out that 140-denier thread is twice as heavy as 70-denier thread, 210 is three times as heavy, and so on. Using the denier system retroactively tells us that 8/0 UNI-Thread is 72 denier, 6/0 Danville's Flymaster is exactly 70 denier, and surprisingly, 6/0 UNI-Thread is 135 denier—no wonder it seemed so much stronger; it's almost twice as heavy!
Thread, Lead, Wire & Tinsel
THREAD, LEAD, WIRE AND TINSEL AND HOW TO USE THEM - FLY TYING
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