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About  Thread

For my personal tieing, I use primarily Lagartun ,Wapsi Ultra 70 and 140, and Gudebrod 45 denier polyester and Veevus 30 denier gel spun,  along with Wapsi 130  or Wapsi 75 denier gel spun for deer hair work.  These threads provide the right strength, size, and appropriate attributes such as the ability to flatten that I find makes tieing durable and beautiful flies much easier.


In the summer 2004 issue of Fly Tyer, author Lyle Morgan addressed the question of whether standardizing thread size would help tiers become more effective in producing beautiful and effective flies. It certainly makes sense to have standardization, which would eliminate much of the confusion that surrounds fly tying thread today. Based on the fly tier web poll conducted in the same issue as Lyle’s article, voters overwhelmingly agreed (252 to 32) that thread should be standardized. The process has been almost fully implemented over the  past eight years.   Most thread spools with a few exception put the denier rating on the spool label.  ”Fly Tyer” magazine includes the appropriate denier in all of the fly pattern recipes.  This has been a hugh help in slowly educating their readership on this correct method of measuring thread.

Tom Schmuecker of WAPSI started the denier information process by introducing WAPSI UTC 70 and 140 denier threads in 1998. His purpose in using the denier number rather than the “aught” was to try and subtly suggest that this system was more beneficial to the tier than the “aught” system that had existed for more than seventy years. Denier is also a recognized and accepted standard of measurement among thread manufacturers and the garment industry.  The term “denier” was coined by the French in 1535.  It is not a new term.

A good example of the misuse of the “aught” system is Gordon Griffith 14/0 Sheer thread.  This thread is acutally a 72 denier thread, but the aught rating would suggest it is much smaller than other threads in the 70 denier category.  The use of the 14/0 rating was designed to mislead the unsuspecting fly tier.  Another clue is that the breaking strength when test by Bill Merg was 10 ounces.  I obtained the actual denier rating from a representative of the late Gordon Griffith’s company who contacted the manufacturer for the denier rating on all of the threads that they sold.

Another good example of how confusing the “aught” rating can be is a comparison of Gudebrod’s 10/0 polyester thread, Bennechi’s 10/0 thread.  The denier of Gudebrod 10/0 is 45, and Bennechi 10/0 is 120.  The aught system does not allow an apples to apples comparison.  Using denier does provide a good comparison between threads.

The late Jean Guy Cote’ of UNI Products was already putting the denier on a number of his products in 1995. He stated, however, ” I won’t put the denier on the 8/0 thread until I am sure that all of the other distributors are using the same measurement system to identify the denier of their thread”.  He had already identified in a chart the denier of all of his products. This information is available to anyone requesting it.

Although Gudebrod closed the company in 2006, at the time I interviewed Paul Black of Gudebrod he stated, ” I have already started to put the denier number on the labels of our thread since we do all of our printing in house” Of course, this process may take a year or more to complete given the number of thread sizes (7) and the multitude of colors. These new labels will begin to show up in fly shops gradually as the proprietors order new stock.  Gudebrod thread is still available in some shops even today.  I still have a reasonable selection of sizes and a number of colors.

Danville manager, Dan Bezanson, stated, “Wherever possible, Danville will include the denier on the spool label.” A few labels may not contain the denier due to unavailable space. Danville recently introduced a 140 denier thread that does not have an “aught” designation.

Giorgio Benecchi Products, of Modena, Italy, does not have labels on their spools. However, they do provide this information freely to shops or distributors. In my own shop, I use a rubber stamp to put the denier as well as the “aught” rating on each spool of Benecchi thread.

Historically the “aught” system began in the late 1930’s. Dan Bezanson said, ” Based on the information that has been handed down in the company, Danville Chenille implemented the “aught” system to help standardize fly tying thread. This was based on a system where the number 0 or “aught” was the base point and as the thread became smaller additional zeros were added indicating that the thread was finer. As an example, a thread with six zeros (000000) translated to a 6/0 thread. As other thread distributors came into the market place after the early 1960’s, they followed the same system which was assigning an arbitrary number that does not necessarily provide as accurate a measurement for the fly tier as denier.

As more thread distributors and brands became available, the accuracy of the “aught” became muddied. When only one distributor existed, making some sense of the system was not difficult. Now there are at least seven distributors of thread in what has become a very competitive market. It occurred to me in the mid 1990′s that some of the aught numbers being assigned to some thread was a matter of trying to gain a competitive edge rather than providing accuracy for the fly tying customer. That is precisely what Denier is defined as the weight in grams of 9000 meters of nylon, polyester, rayon thread, etc. There is a correlation between denier and breaking strength of nylon and polyester thread. The smaller the denier numbers the lower pound / ounce breaking strength of the thread. At the present time, about the smallest denier nylon or polyester for fly tying thread is 20, which would be used for tying midges. The one exception to this denier vs. breaking strength rule is that gel spun polyethylene thread is two to three times stronger than nylon or polyester thread of the same denier.

Denier is only one factor the tier should take into consideration when selecting a thread. The type of material of which the thread is constructed should be considered, whether the thread is a continuous filament, simple twist, bonded, or a rope type. Nylon has about 25% stretch, polyester around 15% stretch, and gel spun only 3% stretch. The type of material being used on the fly as well as the appearance desired also has to be considered. It is important to experiment with all of the various threads available to gain a complete understanding of the pros and cons of each.


Listed below are some of the most popular brands and sizes of threads available. Compare the denier of the thread you are using with others of a similar “aught” size.

Thread Brand Aught Size Material Denier Breaking Strength Thickness (.000)
UNI Caenis N/A mono 20 3 oz. 1.7
Veevus 16/0 polyester 50 12 oz.  *
Veevus N/A gel spun 30 1 lb. 7 oz 1.0
Veevus 14/0 polyester 70 14 oz. *
Veevus 12/0 polyester 70 14oz.  *
Gudebrod 10/0 polyester 45 9 oz. 1.0
Euro Thread 12/0 polyester 45 15 oz. 1.3
UNI 17/0 nylon 40 5 oz. 2.0
Danville Spiderweb N/A mono 30 5 oz. 2.0
Roman Moser Power Silk 8/0 gel spun 55 2 lbs. 6 oz. 1.3
WAPSI 50 GSP N/A gel spun 50 2 lbs. 5 oz. 0.8
UNI Cord 12/0 gel spun 50 2 lbs. 7 oz. 0.9
Benecchi Ultra Strong N/A gel spun 50 2 lbs. 6 oz. 1.3
Benecchi Ghost N/A mono 60 11 oz. 3.0
Veevus 10/0 polyester 110 1 lb. 5oz.  *
Gudebrod 10/0 mono 50 2 lbs. 11 oz. 6.0
Gudebrod 8/0 polyester 67 15 oz. 1.8
Benecchi 8/0 polyester 150 1 lb. 13 oz. 2.2
Veevus 8/0 polyester 110 1lb 7 oz.  *
Benecchi 12/0 polyester 70 15 oz. 1.9
Lagartun N/A polyester 74 1 lb. 1.2
Gordon Griffith Shear 14/0 polyester 72 14 oz. 1.8
Montana Fly Co 8/0 nylon 72 14 oz. 1.4
Gudebrod GXI gel spun 70 4 lbs. 4 oz. 1.0
Danville 6/0 nylon 70 11 oz. 1.5
UNI 8/0 polyester 72 15 oz. 2.0
WAPSI UTC 70 N/A nylon 70 13 oz. 1.1
Lagartun N/A polyester 95 1 lb. 1 oz. 1.4
Gordon Griffith Wisp 8/0 polyester 108 15 oz. 2.2
Veevus 6/0 polyester 110  1 lb. 8oz.  *
Montana Fly Co 6/0 nylon 110 1 lb. 7 oz. 2.0
Gudebrod 6/0 polyester 143 1 lb. 15 oz. 2.3
Benecchi 10/0 polyester 120 1 lb. 6 oz. 2.0
Danville Monocord 3/0 nylon 116 1 lb. 10 oz. 2.6
UNI 6/0 nylon 135 1 lb. 13 oz. 2.9
WAPSI UTC 140 N/A nylon 140 2 lbs 12 oz. 1.6
UNI Cord 7/0 gel spun 100 5 lbs. 9 oz. 1.4
WAPSI GSP 100 N/A gel spun 100 6 lbs. 15 oz. 1.2
Gordon Griffith Cobweb 2 N/A polyester 134 4 lbs 3 oz. 4.1
Wapsi N/A gel spun 130 6 lbs. 8 oz. 2.0
Veevus N/A gel spun 150 8lbs. 4oz.  *
Roman Moser Power Silk 6/0 gel spun 110 4 lbs. 8 oz. 1.3
Gudebrod 6/0 mono 143 2 lbs. 11 oz. 6.0
Lagartun N/A polyester 150 2 lbs. 1.9
Danville Flat Waxed Nylon N/A nylon 210 2 lbs. 14 oz. 2.0
Danville Fly Master Plus N/A nylon 210 3 lbs. 2.8
UNI 210 N/A nylon 210 3 lbs. 3 oz. 2.0
Gudebrod 3/0 polyester 176 2 lbs. 6 oz. 4.0
UNI 3/0 polyester 266 2 lbs.  *
Montana Fly Co 3/0 nylon 135 1 lb. 9 oz. 2.2
WAPSI UTC 210 N/A nylon 210 3 lbs. 5 oz. 3.2
Gudebrod G N/A mono 210 3 lbs. 7 oz. 7.0
Gudebrod G N/A polyester 330 3 lbs. 11 oz. 3.5
Montana Fly Co N/A nylon 350 4 lbs. 4 oz. 3.2
UNI Big Fly Thread N/A nylon 440 5 lbs. 4 oz. 3.5
WAPSI UTC 280 N/A nylon 280 3 lbs. 14 oz. 2.7

Bill Merg conducted the tests on 15 threads that have become available in the past several years. All of the other data listed in the chart is from the 1996 test results. He used the same methodology in testing the various new threads that have become available in the past 20 plus years, as well as the tests conducted for the thread listed in the 1996 article entitled “Testing the Ties That Bind”, that is mentioned above. On all of the tests conducted in 1995, the various brands showed remarkable consistency in thickness throughout the spool. That was not the case in a number of the threads recently entering the marketplace. Those that showed slight variation in thickness included: (variation shown) WAPSI 210 (.008), WAPSI 280 (005), and Danville 140 (006), Roman Moser Power Silk 6/0 (0012). Keep in mind that one spool was randomly selected and used for these tests.

Another thread article by Ed Engle in the spring 2000 issue of Fly Tyer entitled “Hanging by a Thread” compares twelve different threads for tying small flies. Then he rates the threads in a manner similar to how Consumer Reports evaluates products. This same article appears in Ed’s book Tying Small Flies. Ed describes the qualities of twelve threads and discusses the characteristics of each.

Darrel Martin wrote an excellent article on thread in the March/April 2000 of Fly Rod and Reel entitled “A Thread of An Idea”. He discusses silk thread and its history along with numerous facts about thread sizing, characteristics of the each material used in thread. He also comments on thread pressure applied when tying and characteristics of waxed thread. Matching the thread to the size of the fly and the material being used is extremely important in achieving both functional and aesthetically pleasing flies. The more a tier understands about all the materials used in tying the fly, the more efficient and effective fly tier he or she will become.

The newest thread to be included in this chart is Veevus, a product from Denmark.  I was able to obtain the denier on a few of the sizes, but not all of them.  The owner of the company is

not willing to release this information which is puzzling.  In those instances, I based the denier on the breaking strength of the thread after obtaining an average after 10 tests.   A majority of the Veevus threads sizes are twisted thread rather than semi-twisted or flat.  Twisted thread is stronger for the same diameter and denier than semi-twisted or flat thread.  This may explain some of the number not appearing to be accurate.  I tested the thread with the same testing tool as Bill Merg used, and I ran ten tests on each size and took as average of those ten.  Thread thickness will be entered at a later date.




Shop Thread

Giorgio Benecchi 12/0 Thread 70 denier

This is one of the more popular threads with my customers.  It is unwaxed polyester made in Italy.   A good choice for midges, dry flies, nymphs, small salmon flies, Carrie Stevens streamers or any other patterns where the bulk must be minimized.  Colors: black, white, light dun, olive, dark dun, sandy dun, green, dark green, light yellow, brown, orange, wine, red, pink, tobacco, emerald, light tobacco, damsel fly blue, dark blue, magenta, and dark brown. Breaking strength 15 oz.  Per 100 meter spool.  Semi twisted and lays flat. Giorgio Benecchi closed his wholesale materials business in December 2012.  There is a fairly good supply remaining of this size thread.
Price: $3.50

Lagartun Thread 74, 95, 150 denier

Imported from France. Arguably the best polyester thread available today for the modern fly tier. This thread and the Wapsi nylon 70 and 140 are my favorite threads for tying dries, wets, nymphs, and streamers.   The strength tests that Bill Merg ran on this thread proved Lagartun to be the most consistent of all the various thread brands currently available. Although it is priced higher than all other polyester and nylon threads, it is worth the money. Most tiers can easily get by with three or four colors, so the cost is really not that excessive. Also no other thread is available in the in between size of 95 denier that is perfect for so many patterns. Lays flat. My favorite color is the Iron Gray.  No other thread manufacturer has this unique color. Colors: 74 denier: black, white, olive, iron gray, burnt orange, marron (brown), fluorescent orange, red, rust, fluorescent red, and beige. 95 denier: black, white, olive, iron gray, red, fluorescent yellow, fluorescent green, marron (brown), beige, and rust. 150 denier: black, white, olive, iron gray, amber, rust, beige, burnt orange, fluorescent green, and fluorescent pink. Per 100 yard spool.
Price: $4.65

Thread Rack by Oasis Fly Tying

This lacquered finished oak thread rack holds up to 120 spools of thread, tinsel, floss, wire, lead, or any combination of standard thread size spooled material.  The rack measures 7" x 12" and sits at a 30 degree angle.  There are six rows with 10 holding rods in each row.  Each brass rod holds two spools.  Made in the USA.
Price: $39.95

Giorgio Benecchi Ultra Strong Thread 55 denier.

Breaking strength 3 lbs. plus. Gel spun Polyethylene material. White only. Per 50 meter spool.  This is my favorite for doing medium size small hair flies.
Price: $4.50

Wapsi 130 Gel Spun Thread for Hair Bugs

This is the same gel spun thread which Gudebrod sold as GX2. Without question this is the most appropriate size gel spun for size 4 and larger bass bugs, hair pike patterns, etc. This is my favorite thread for doing hair bugs that has been on my designated "hair bobbin" for at least 10 years.  There are also 150 and 200 denier gel spun listed in the website.  I think these are overkill for bass bugs or similar flies.  Color: white. 50 yards per spool.
Price: $3.75

Pearsall's Gossamer Silk Thread

This thread is on small spools requiring use of a Wasatch Micro Bobbin or similar bobbin. Colors: black, white, java brown, purple, brown, light olive, gray, jasper, lemon yellow, golden yellow, pale yellow, amber, olive green, scarlet, hot orange, claret, and antique gold. Per spool.
Price: $3.98

Uni Underbody Wrap 560 denier

A flat  nylon used to wrap flat, smooth underbodies on any streamer, classic salmon fly, or nymph hook. Use before wrapping tinsel or other material for the outer body. The material is a heavier version on Unit-Stretch. Lays flat and tapering bodies is easy with this material.  Color: white. Per 30 yard spool.
Price: $1.50

Giorgio Benecchi Iridescent Thread

This is a metallic type thread that can be used for wrapping bodies or heads on larger patterns ribbing, etc. twisted. 30 meters. Colors: olive, rainbow, white, light pink, orange, yellow, hot orange, red, violet, indigo (dark blue), light lilac, peach, light olive, and sapphire. Per spool.  This material is the same product as the "Midge Body Thread" list in this product category.  The colors are more geared to trout pattern with the Midge Body material.
Price: $2.79

Danville Monocord 3/0 116 denier

A medium heavy thread for large nymphs, small to medium saltwater patterns, light deer hair work, etc. Breaking strength 1 lb. 10 oz. Color: black, white, gray, beige, olive, yellow,orange. Per waxed 100 yard spool.
Price: $1.85

Roman Moser Powersilk 150 denier gel spun

Breaking strength 5  1/2 lbs. This thread is for very large saltwater patterns. Colors: light fluorescent green and fluorescent yellow. 150 denier.   Per 50 meter spool.  Roman sizes this thread 1/0. This thread could be used for hair bugs and large saltwater patterns as well as for attaching lead bar bell eyes to your hooks.
Price: $6.89

New- Veevus 30 Denier Gel Spun Polyethylene

This thread is "awesome" as the young folks like to say. It is less than half the size of the typical 70 denier polyester or nylon and twice as strong. The breaking strength is one pound seven ounces. I have tied a broad range of flies from large streamers to midges, and it is an optimal size or just about any pattern except larger bass bugs and saltwater flies. White only. 75 meters per stool. If you like to tie very small flies under size 18 this is the thread to use.  It is also excellent for smaller hair flies such Goddard Caddis, Irresistibles, small muddler and hopper heads.  If you tie parachute patterns this thread allows you to tie off the hackle on the parachute post and you won't see the thread.  It disappears. Per spool.
Price: $3.75

Montana Fly Company Premium Thread 110 denier

Suitable for tying dries, nymphs, and streamers in size 2-10. Colors: black, white, olive, cream, gray, pale yellow, light brown, light olive, rusty brown, brown, sand, orange, fl.yellow, dark brown.  Lays flat.   Per 100 yard spool.
Price: $1.50

Danville Fine Mono Thread

A fine clear mono thread. Diameter .006" - 100 yard spool.
Price: $1.50

Giorgio Benecchi Ghost Thread

This is a 60 denier clear monofilament thread.  Used on various saltwater pattens.  100 meters per spool.  Thread thickness is .004.  Each.
Price: $1.75

Uni Products Glo Yarn

This white phosphorescent yarn emits light in total darkness for up to three hours. The phosphorescent material is extended into the fiber so that it cannot be washed out. Uses include trailing shucks tags bodies wing cases, etc. Per 7 yard spool.
Price: $1.00

Danville Depth Ray Nylon Wool

This product has been a staple of Danville for years. It is a narrow two strand yarn. Colors: all fluorescent - red, orange, blue, green, white, fire orange, pink, and yellow. Per 10 yard spool.
Price: $1.00

Metallized Thread

Imported from England. A fine metallic thread that can be used as ribbing body material or thread on small flies from 18 24. Color: gold. Per spool.
Price: $1.50

Uni Thread 17/0 20 denier

Micro fine for midges. White only.  20 denier. Per spool.
Price: $1.50

Gudebrod 10/0 45 denier

I was able to purchase the remaining supply of Gudebrod 10/0 (midge thread) in bulk spools after Gudebrod stopped making fly tying thread in 2006. Wapsi Fly, Inc. has agreed to spool the thread for my shop on their spools. The remaining colors include the following: white, tan, gray, light rusty brown, yellow, light gray, dark olive, dark rusty brown.  45 denier. Per 100 yard spool.  This is a true midge thread for those that enjoy tieing size 18 and smaller flies.  The breaking strength is 9 ounces.  It teaches you good thread pressure skills.
Price: $2.50

Danville Flymaster Plus 210 denier

A moderately strong semi- twisted thread for medium to small hair bugs, saltwater and other large patterns. Waxed. 100 yard spool. Breaking strength 3 lbs. Colors: black, white, tan, red, pink, gray, fluorescent orange, fluorescent green, maize, light olive, olive, coffee, fluorescent blue, fluorescent yellow, and tobacco brown. 210 denier.  Lays flat.  Per spool.
Price: $1.65

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