By. Christopher Helm
In the late 1930's, the Chenille Company created the "aught"( 3/0,6/0, 8/0, etc.) system to indicate the size of thread. This was based on a system where the number 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 were born after the early 1960's, they followed the same system which was assigning a standard that does not provide as accurate a measurement for the fly tier as denier. In 1988, Tom Schmucker of WAPSI Fly, Inc. in Mountain Home, Arkansas introduced a nylon thread simply called 70 UTC and 140 UTC based on denier, which is the method of measuring thread. This is the system that the garment industry uses for thread to sew clothing. 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 number 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 40, 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 that nylon or polyester of the same denier. This transition to a denier rating system will take several years to be completed. Danville and Gudebrod are committed to making changes as they order new labels. UNI-Products has already begun the transition.
Interesting and something I often wondered about since I saw the measurement, but had no idea what it meant.
ReplyDeleteI read long ago various articles by authors such as Helm, Ed Engle and the late Dick Talluer describing this alternative to the ought system. Engle even illustrated his piece with the tying of a #22 flashback PT and how different threads worked, or did not, in tying this fly. It makes sense. What also makes sense is a tyer's experience, both in old preferences, and the ability to judge new threads for his/her uses. Chris, the deer hair master, ought (no pun intended) to know all of this well. The wild card would be the materials used for the thread, whether it is bonded or not, and also is the spool adaptable to standard bobbins, some are loose actually.
ReplyDeleteGood stuff, Gregg
I think there are even thinner thread than 40 denier. Like Uni Caenis 20/0 for example. I agree though that the system of measuring fly tying thread should change.
ReplyDeleteHave fun Gregg
The Jassid Man,
ReplyDeleteI have gone to fishing almost entirely for carp, almost. But trout are my foundation and I enjoy tying it all. Is the Uni Caenis strong enough to finish a Klinkhammer done by Han's method? That is, finishing tying off the hackle on the post. I use a fine Orvis thread of 12/0 as it comes in colors other than white. By the way, Klinkhammers are one of a few top water flies I carry for carp.
Gregg
Thanks for posting this. I have always hated the aught system. It is only of any utility when evaluating threads from a single company.
ReplyDeleteIt makes me think about the early days of steam locomotives, when each maker of engines had an arbitrary gauge track that only could be used by their trains...
We need to have a Geneva convention to standardize thread weights, hook sizes, and credit card terminals. Then life would be perfect.
SS
How about a system that is determined by the actual diameter of the thread, vs breaking strength? Larger diameter thread will generally be of higher breaking strain anyway - but some patterns really do call for fine diameter thread. Denier system still doesn't correlate to diamter - it has to do with breaking strain. As Jay pointed out - different materials will have different diameters, but the same Denier rating. I'd rather see something like the "X" system tippets use, that would denote thread diameter.
ReplyDeleteMark,
ReplyDeleteGood idea. OX=.011,1X=.010, etc. Some fine mono threads do make tippets and occasionally you see the diameter as well. That would work. Still, as far as breaking strength goes, a well informed/experienced tyer would choose the material, GSP, polyester, nylon, others, that he or she knows would perform for the tying task involved.
Gregg