We all know that fly tying materials with their varying names and non-standardized labels can be confusing. Thread selection is a perfect example. Staring at a wall of fly tying threads at your local fly shop can feel intimidating.

We touched on this topic in a blog post a couple of years ago, so we thought it would be worth revisiting. Where should you start when choosing thread? 

The Simplest Way to Begin

Fortunately, we have a number of talented fly tyers on staff here at Anglers All. Umpqua signature tyer, Daryl Eakins, had some good advice as we begin understanding threads. 

Daryl suggested that the easiest way to get started is by following a specific fly pattern. If the instructions say to use 8/0 thread, then use 8/0 thread. He says it’s not unlike cooking in that way. The more recipes you follow and the more ingredients and spices you become familiar with, you’ll get to know them over time and become comfortable using them in different applications.

“When just starting out, it is important to think about what you are tying and what thread is recommended,” Daryl explained. “Over time, you’ll gain more context, based on the threads you have already used.”

You probably wouldn’t go to the spice aisle at your grocery store and begin loading up on spices with no plan for how to use them. Likewise, Daryl says there is no need to go to your fly shop and buy a whole bunch of different threads to get started. 

“I would recommend only buying what you need, when you need it,” he said. “Look at any fly shop's thread selection as a spice rack, and once you familiarize yourself with the spices, you’ll be more likely to use them.”

Over time, as you learn to tie more patterns, you’ll naturally build up your library of threads at home. 

Understanding Fly Tying Threads

While following a specific pattern is the simplest way to begin, there are some basic things to know about threads that will help you become a more educated fly tyer.

“First, it’s important to know that Denier and thread thickness do not correlate,” Daryl explained. “The aught (X/0) system measures diameter and the denier system measures weight. However, notice that neither of these systems measure strength.

“Strength comes from the make-up or material of the thread, like polyester, nylon, GSP, or silk,” Daryl continued. “This information is not intuitive. But it’s so helpful to know, so as not to confuse the weight, thickness, diameter, or strength of a thread.”

Common Applications

Umpqua signature tyer, Ben Baxter, agrees that the pattern you intend to tie, and the hook size will help determine what thread you need. Ben and Daryl offered some basic guidelines. Keep in mind, these are not hard and fast rules. These are simply some of the more common applications… 

• Flies Sizes 18 and Smaller: Semperfli Nano Silk Ultra is ideal. You could also use thread 16/0 or even up to 8/0 or 70-denier, depending on the pattern.

• Midges, small emergers, and small dry flies: 14/0 or 32-denier

• Nymphs & dry flies: 8/0 or 70-denier

• Larger nymphs, larger dry flies, streamers, and smaller saltwater flies: 6/0 or 140-denier

• Saltwater, warmwater, larger streamers, bucktail flies, poppers and deer hair flies: 3/0 or 210 to 280-denier

• Toothy critters, deer hair flies, and bucktail flies: GSP and Silk 

“Of course we can go down lots of rabbit holes when it comes to thread characteristics and when to use them,” Ben added. “These are some basics to help us put different threads into context.”

Common Thread Types & Materials

Daryl reminds us that thread material and composition is what makes it strong, not the denier or other labels. Here’s a quick look at the make-up of different threads and what fly tyers should know about each: 

UNI Thread: UNI has a matte finish, it’s a polyester material with minimal stretch, and it’s a corded thread.

UTC Thread: UTC has a shiny finish, it’s a nylon thread with considerable stretch, and it lays flat, allowing it to wrap smoothly on the hook.

Danville's Waxed: this is a nylon thread and therefore has some stretch, it’s available in a wide color selection, and it lays flat.

Veevus Power Thread: this is a polyester thread, so it has little stretch, and it’s very strong.

GSP: GSP stands for gel-spun-polyethylene. It has very little stretch, it’s slick, it lays flat, and it is very strong.

Semperfli Nano Silk: this is a silk thread that lays flat, is translucent and is extremely strong.

Semperfli Classic Waxed: this is a polyester thread with a matte finish.

Danville's Flymaster Plus: this is a nylon thread, it’s available in a wide color selection, and it lays flat.

UNI Floss: this is a multi-strand rayon material that comes in bright colors, is very strong, and often used for body wraps.

Questions to Ask When Selecting Thread

According to Ben and Daryl, these are some helpful questions to ask yourself whenever you’re selecting thread: 

“First and foremost, what pattern are you tying and what hook size will you be tying this on?” Ben offered. “We can worry about color and other factors later.”

Next, Daryl suggests asking yourself if you want a thread that lays flat or is corded? Consider that corded threads will bite into materials effectively. While flat threads will provide a slimmer profile. Remember though, you can always spin your bobbin to open up a thread for a slimmer profile. Spin it counterclockwise if you’re a right-handed tyer. Or you may wind any thread tighter for tying in materials. Spin it clockwise if you’re right-handed.

Other questions you might ask yourself include, ‘Do I want a thread with little stretch or moderate stretch?’ You might also ask, ‘Do I want a thin diameter thread for small flies, or do I want a strong thread for streamers or deer hair?’

“Don't be afraid to ask yourself questions to find a more accurate thread choice,” Daryl told us.

Ask For Help and Use Multiple Resources

The more you tie, the more you will get to know different threads and techniques for using them in different patterns. Along the way, don’t be afraid to ask for help.  

Here at Anglers All, we have a number of dedicated fly tyers on staff, including three Umpqua signature tyers. Take advantage of their knowledge! Stop by the fly shop for help or give us a call at 303-794-1104. 

Take advantage of all the resources at your disposal. We have a fly tying video catalog that includes more than 120 different patterns. These in-depth videos are a great way to learn how to tie new fly patterns. 

If you’re in the Denver area or along the Front Range, consider joining us for a fly tying class. We offer fly tying 101 as well as advanced tying classes.

You can shop our online selection of threads here. Or you can check out the rest of our fly tying tools and materials here.