The Use of Thread

By:  Ed Gallop

Thread Comparison Chart

Proper Tension

Attachment to the Hook

Silk threads were used for fly tying long before nylon and polyester came on the market.  Silk is still used by tiers of classic flies and by those that simply prefer it.  However, the most commonly used tying thread is polyester, followed by nylon, and then silk.  Personally, I have all three on my desk and each has it's own specific use.

Polyester is easier to handle so is used for most of my tying needs.  Nylon monofilament has brighter colors and is stronger.  However it has an undesirable smoothness, stiffness, and it stretches.  It's strength and smoothness is an asset when spinning hair (flaring for hair bugs) but the stiffness and smoothness make it harder to handle and causes it to slip on the hook.  I also believe the stretch characteristic of nylon monofilament may cause it to relax over time and thus slightly loose it's grip.  It will not lay as flat as most polyester but the colors make nice bright heads.

Thread Chart:  Below is a thread chart with breaking strength and denier estimates for several threads to help you select the best thread for your needs.  Most tying thread use diameter measurements (example; 3/0, 6/0, 8/0, etc) but Denier measures weight.  Denier is the number of grams in 9,000 meters and it is used in the textile as a means of measurement.

Uni Product Denier/Size Breaking Strength Comment
Uni-Thread 17/0 40 4 oz 1 color (Midge)
Uni-Thread 8/0 72 16 oz 21 colors
Uni-Thread 6/0 135 1 lb 13 oz 24 colors
Uni-Thread 3/0 215 2.01 lbs 17 colors
Uni-Nylon 70 70   3 colors
Uni-Nylon 210 210   3 colors
Kevlar 200 8 lbs 6 oz 1 color
Big Fly Thread 400 6 lbs 4 oz 11 colors
Uni-Cord 12/0 GSP 50 4 lbs Gel Spun - 6 colors
Uni-Cord 7/0 GSP 100 8 lbs Gel Spun - 6 colors

Uni Big Fly

  100 OZ  

Uni A Nylon

  44 OZ  

Uni A+

  60 OZ  

Uni Neon 1X

240 36 OZ  

Uni Poly II

  34 OZ  
Mono-Thread, Fine .004" 1 lb 6 oz Clear
Mono-Thread, Med .007" 3.11 lbs Clear
Mono-Thread, Large 010"   Clear
Uni-Floss 600 2.12 lbs 30 colors
Uni-Stretch 280 3.5 lbs 20 colors
Micro-Tinsel 3/0   1.06 lbs  
Wire, Extra Small .10mm 1.72 lbs  
Wire, Small .15mm 3.81 lbs  
Wire, Medium .20mm 6.91 lbs


Other Product Denier/Size Breaking Strength Comment
  Benecchi 8/0     28 OZ  

Benecchi 10/0

  24 OZ  

Benecchi 12/0

  16 OZ  
Fly Tying and Fly Fishing: