Silk Fly Line is considered by many to be the more traditional fly line and therefore some prefer it when fishing with Bamboo Fly Rods. Brasstown Creek sells Phoenix Silk Fly Lines and we use these Fly Lines ourselves. Although Silk Fly Lines can be furled (similar to Furled Leader), for the most part Silk Fly Line is braided.
The Phoenix Silk Fly Line which Brasstown Creek sells (and fishe with) is braided from pure silk filaments. In order to get the proper taper in the line, filaments are added or removed (depending on your point of view) during the braiding process. Because of this requirement to cut or add silk filaments to get the appropriate taper, a manufacturer can’t make a long run of line, e.g., only one line at a time can be made on each braiding machine (often as slow as only 66 inches per hour). After braiding, the newly made silk fly line must be treated to become water resistant as well as prolong the fly line’s life. Top quality lines could get as many as a dozen separate coats of Linseed Oil with a drying time between coats of 5-15 days (see “America’s Fly Lines by Victor R. Johnson, Jr.).
Some manufacturers sell the silk fly line without treatment, leaving it up to the buyer to complete the line preparation. This practice usually results in significant savings to the buyer, but of course requires a lot of effort before the silk line can be fished. Phoenix Silk Fly Lines are treated at the factory and come ready to fish when you get it. Still, it isn’t a bad idea to apply a coating of Red Tin Mucilin before starting (we do). Our results with Phoenix Silk Fly Lines have been excellent.
The USGS has a good article on water properties (check out the density and weight section) at http://water.usgs.gov/edu/waterproperties.html should you be interested. The USGS article provides some good charts of water density at various temperatures. The standard density for pure water is 1.00000 grams/cubic centimeter (at 4 degrees Centigrade, which is the temperature at which water is most dense). As information, density is measured in mass per volume (e.g., grams/cubic centimeter) whereas specific gravity is the ratio of one density to another. Water is commonly the denominator when calculating specific gravity. Wolfram Schott has written an excellent article about Silk Fly Liines which can be found at www.powerfibers.com/Schott_Silk_Lines_Letter.pdf if you would like to read more.
Essentially all modern fly line float because the specific gravity of the line is less than one (a given volume of fly line weighs less than an equivalent volume of water). Not so with Silk Fly Line. Silk Fly Line has a specific gravity greater than one; hence it can be expected to sink. However, when properly treated with a floatant (manufacturers use boiled linseed oil, varnish, a mixture of both, or a proprietary concoction), the line becomes supple and water resistant. That allows the Silk Fly Line to ride on top of the water due to surface tension (the same way a water strider stays on the surface). Being more dense than its modern counterpart, Silk Fly Line has a smaller diameter that its counterpart of equivalent weight class (for example, a 5wt Silk Fly Line would have a diameter comparable to a 4wt modern counterpart), thus you get less air resistance and easier pick up from the water.
Even the most scrupulously treated Silk Fly Line will eventually absorb water and begin to sink, how long you can fish before this happens depends on the quality of the braided line, the quality of the finish, and how well you have cared for the line before, during, and after fishing. I have been able to fish as long as 7 consecutive hours before my line began to sink, but the time is usually a bit shorter. Your Silk Fly Line must be thoroughly dried before you apply a floatant such as Red Tin Mucilin; doing so before it is fully dry can seal moisture in the fly line and cause mildew or rot. If you don’t have a line dryer, you can simply dry your silk line by unwinding it from your reel in large loops so they will get plenty of air.
Care and Maintenance Tips:
1. Don’t fish with Silk Fly Line at low temperatures (freezing or below). Ice forming on your guides and tip tops will damage the silk line as it shoots through. Furthermore, the line treatment (for example, Red Tin Mucilin) can stiffen at low temperatures making casting less effective. I learned both these cautions the hard way.
2. Keep the line clean. Periodically inspect your Silk Fly Line to see if dirt and grit are adhering to the line treatment; you have to apply Red Tin Mucilin to your line, but too much of it just attracts contaminants.
3. After each day’s fishing, thoroughly dry your Silk Fly Line to prevent mildew and rot. While a fly line dryer helps make this easier, you can simply drape long coils of fly line over whatever furniture you don’t mind getting a little moisture on (I usually do this in my workshop as I have yet to find furniture my wife will let me get wet). Don’t forget to dry the fly line backing while you are at it. If you don’t, then the moisture in the backing will re-dampen the Silk Fly Line when it is re-wound on your fly reel.
4. After your Silk Fly Line is completely dried, apply a thin coat of Red Tin Mucilin to the fly line as you wind it back onto your reel. I apply this in small increments, maybe three or four feet of line at a time, by wiping on the Red Tin Muciln with its accompanying pad then wiping off any excess. I do this to the full length of the fly line. If it is a few weeks before my next fishing trip, I usually reapply a thin coat of line treatment to the last thirty or so feet of the fly line.
Silk Fly Line takes more care than current synthetic fly lines, but has its own unique properties that many (including me) prefer. And, at least to my ears, the Silk Fly Line “sings” when I cast it.