UTC 140 (6/0) Excellent for the majority of flies, it is the perfect choice for size 2 – 16 flies. Due to its vibrant sheen and excellent color retention, it is a good substitute for floss on small flies.
UTC selected nylon over polyester because nylon will stretch and grip materials better. This allows for more uniform tension and gives the tyer the “feel” for maximum tension. Nylon is the same strength as polyester (given the same denier) and offers the added benefit of more intense colors and a larger range of colors. Because nylon stretches, it grips material tighter and makes the fly more durable.
UTC’s thread is flat with only the minimum number of twists needed for production. This is important because the number of twists in the thread determines how flat it can be wrapped on the hook. The flatter the thread is wrapped, the more slowly it builds up. This is a huge advantage when tying small flies or when tying close to the eye of the hook. A flat thread also grips and covers materials with fewer thread wraps.
Ultra Thread has been lightly waxed. This also limits thread build up and gives the thread a smoother, slicker feel. The added benefit is that head cement fully penetrates the thread which equals more durable flies.
Ultra Thread is a multifilament thread that is not bonded. Bonded threads are oval in shape and are stiff or coarse feeling. Bonded threads also build up fast which is a significant concern when tying small flies. Since Ultra Thread is not bonded, it is the best choice for split thread tying techniques