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.

Kevlar thread is much stronger than nylon or polyester but it has a reputation for wearing out scissors.  Kevlar is easily cut with a sliding motion of the blade but not by compression so it is best to slide the opened scissor blades rather than closing the blades on the Kevlar.  This is also the case with G.S.P., which is even stronger than Kevlar. 

G.S.P. thread was developed for the medical profession but has become quite popular for fly tying, especially when spinning hair.  It is the same material used in "Spider Wire" fishing lines.  I recommend placing a drop of cement on the shank before attaching G.S.P. or Kevlar thread because it is slick and has a tendency to slip on the hook shank. 

Proper Tension:  Tight thread tension is very important to prevent materials from slipping.  You should normally use as much tension as possible without breaking the thread, especially attaching materials such as hackle stems, tinsel, and other thick or stiff materials.  It isn't necessary to wrap that tight with good strong thread but it is necessary to be very snug.  There are situations where you might wrap with less tension.  When attaching fragile material, such as peacock herl, I normally attach it to the hook tightly but use less tension with wraps over the exposed material.  It is best to hold it snug without crimping or mashing which may cause the material to break when the fly is used.

Tight thread tension is very important to prevent materials from slipping.  You should normally use as much tension as possible without breaking the thread, especially attaching materials such as hackle stems, tinsel, and other thick or stiff materials.  It isn't necessary to wrap that tight with good strong thread but it is necessary to be very snug.  There are situations where you might wrap with less tension.  When attaching fragile material, such as peacock herl, I normally attach it to the hook tightly but use less tension with wraps over the exposed material.  It is best to hold it snug without crimping or mashing which may cause the material to break when the fly is used.

Choose a good quality bobbin holder for your thread because some inexpensive bobbins may have rough tubes that will snag and break thread as you wrap.  If you find your bobbin has a snag you should buff it out smooth.  I use a Dremmel tool but a drill will work.  You can buy small buffing pads in K-Mart or even building supplies.  Some have used erasers on the end of a pencil or ink pen. 

It is also recommended to have a good pair of scissors dedicated only for thin threads and floss.  I suggest non-serrated because thin stranded thread or floss may not cut cleanly with serrated edges.  Use another pair for hair, tinsel, and other coarse materials (serrated is best).  This will keep the non-serrated thread scissors sharper for cleaner cuts.  It is also recommended that you cut tinsel, wire, and other hard materials in the far back of the jaws to keep the mid and tip section sharper for hair.

Attachment to the Hook:  The first thing you will do is start the thread on the hook shank.  This is accomplished by holding the end of the thread in the fingers of your left hand and the bobbin in your right hand.  Wrap a few times as described in the top picture them wrap backward over the initial wraps.  Trim off the tag end of the thread.

This is a good time to get the feel of the thread (as mentioned above).  As you wrap you should put more and more tension on the thread until it breaks.  Do this over and over until you know about when the thread will break.  This will save you a lot of frustration caused by breaking the thread in the middle of tying a fly.  As you progress to lighter thread you might want to do the same test and get the feel of the thread's breaking point.  You should normally tie using maximum thread tension to ensure it will be tight and not slip or come apart.

After securing the thread to the shank then wrap the thread to the rear of the hook shank near the hook's point, or where you want to tie in the tail.  It isn't usually necessary to wrap the thread over the shank with wraps tightly close together, unless you are applying a thin body than required a smooth shank.  You should make at least 10 to 15 tight (close together) wraps at the front, over the tag end of the thread.  Do the same tight wraps at the rear before attaching materials to the hook.  This prevents thread from slipping on the shank.  I'll sometimes reinforce the thread by lightly spreading cement over the thread, especially on large flies, but it isn't necessary in this situation. 

Now you know the basics and you're ready to add material and build the fly.