Fly Tying ·Mar 20, 2025

FLY TYING: Everything You Need To Know About Threads

Fly Tying: Everything You Need To Know About Threads

Fly tying is an art, and just like any craft, having the right materials can make a significant difference in the final product. For beginner fly tyers, understanding the nuances of tying thread is essential to creating effective and durable flies. In this guide, we’ll cover everything you need to know about fly tying threads, including their types, sizes, and how to choose the best one for your flies.

Thread Materials

Fly tying threads are made from different materials, each with unique properties that affect strength, stretch, and smoothness. Here are the most common ones:

Nylon – One of the most common materials, nylon threads are strong, slightly stretchy, and available in various sizes. They are ideal for a wide range of fly patterns.
Polyester – Similar to nylon but less stretchy, polyester threads provide excellent strength and durability. They also hold their color well over time.
Kevlar – Extremely strong and abrasion-resistant, kevlar threads are great for large flies but can be difficult to work with due to their slick nature.
GSP (Gel-Spun Polyethylene) – One of the strongest threads available, GSP is thin yet incredibly strong. It’s perfect for tying small flies while maintaining high durability.

Thread Size and Strength

Fly tying thread comes in different sizes, which can be confusing for beginners. The two primary sizing systems used are:

Denier System – Measures the weight of the thread per 9,000 meters. A higher denier means a thicker and stronger thread.
Aught (/) System – Common in fly tying, this system uses numbers like 6/0, 8/0, and 12/0. The higher the number, the finer the thread.

Here’s a general breakdown:

3/0 (200 Denier) – Best for large streamers and saltwater flies.
6/0 (140 Denier) – Good all-around thread for medium-sized nymphs and dry flies.
8/0 (70 Denier) – Ideal for smaller dry flies and delicate patterns.
12/0 (50 Denier) or finer – Used for ultra-small flies, like midges.

Choosing the Right Thread for Your Flies

Selecting the right thread depends on the type of fly you’re tying. Here are some tips:

For Dry Flies – Choose a fine, lightweight thread (8/0 or finer) to avoid adding unnecessary bulk.
For Nymphs and Wet Flies – A slightly thicker thread (6/0) works well, as it helps secure materials and adds durability.
For Streamers and Large Flies – Use a strong thread (3/0 or lower) to prevent breakage while securing bulky materials.
For Specialized Flies – Consider GSP or Kevlar for flies that require extra strength.

Thread Characteristics to Consider

Flat vs. Twisted Thread – Some threads lay flat when wrapped, reducing bulk and improving fly appearance, while others remain twisted, adding segmentation.
Waxed vs. Unwaxed – Waxed threads provide better grip on materials, while unwaxed threads allow for smoother wraps and less buildup.
Color Choice – Match the thread color to your fly pattern or use contrasting colors for added visual appeal.

Conclusion

Understanding fly tying thread is crucial for creating high-quality flies that are both functional and aesthetically pleasing. By considering the material, size, and characteristics of the thread, you can enhance your tying skills and produce flies that perform well on the water. Experiment with different threads to find the ones that best suit your style and the flies you love to tie!