Weighted Nymphs: Tungsten Wire vs. Lead Wire

weighted nymph 01__Lead_Weight_on_Hook_Shank

Lead Weight on Hook Shank

Guest Blogger: Michael Vorhis, Fly Fisher & Author, FreeFlight Publishing

We all know that key to nymphing for trout is getting the fly to the right depth; more often than not that means close to the bottom. It can be a challenge where depths vary, pocket to pocket and from the head of a run to its tail, and the method of suspending below some kind of floating indicator is not good at letting a fly hug bottom across varying depths. Weight works better for that, but it too has its drawbacks, especially in swift current where drifts can go a long distance before the desired depth is reached. So we add more of it, and we do that in a variety of ways.

Myself, I don’t care so much for bead heads on flies. I know people catch plenty of fish on bead-heads, but…well, I guess those flies may catch fish but don’t “catch” me. The beads are usually shiny little globes and I’ve never seen a larval insect with a shiny globe head. Trout seem to have the ability to ignore that unnatural feature, but my eccentric attitude is often that I’d rather not introduce any source of doubt at all. I use small lead shot on the leader, which I don’t love either but at least it doesn’t alter the look of a fly. What I like best is to add weight to a nymph’s body at the vise, via heavy wire of some kind. It usually introduces at least half the amount of weight I need (and more than a bead-head would), reducing my split shot to a very small amount.

weighted nymph 02__Lead_Weight_Tied_Down_on_Hook_Shank

Lead Weight Tied Down on Hook Shank

The smallest solid lead wire I can find (barring electronics solder which is usually hollow, so lighter) has a diameter of 0.010 inch. (By the way I may be wrong but I do NOT believe that lead wire is detrimental to our streams; like automotive battery terminals, the surface of fishing weights almost instantly becomes the non-toxic, inert substance known as lead oxide, which hurts nothing and no one. The overreactions against the use of lead are more knee-jerk and more ignorantly / social-activistically political than they are scientific. (I salute J.Stockard for not falling for the baseless hoopla and for continuing to provide lead wire for tying flies.) A 0.010 inch diameter is thin enough to wind around hook shanks as small as #18 for nymph thorax areas…and I can wrap in a thin straight bit of such lead wire linearly along the shank on hooks even smaller than that.

But recently I saw, and purchased, some of that new “Tungsten Thread,” to assess whether it’s a superior material for adding weight to any fly. It’s actually very thin tungsten wire, and appears exceedingly strong, so it can be wrapped and even tied in a knot like thread. There are several things I wanted to determine:

  • Workability as compared to lead wire
  • Weight by length as compared to lead wire
  • Weight by thickness (“build-up” on a hook shank) as compared to lead wire
  • Use case opportunities as compared to lead wire

Workability

I acquired and tested the larger of the two sizes, which is called “fine.” It’s practically invisible, so I cannot imagine ever in my life needing the smaller of the two sizes unless I were to tie up a size 60 fly, which isn’t going to happen. The size I tested already looks like a human hair. It’s much more “springy” than lead wire, which means you must take your thread and nail down the starting end, wrap onto the hook, and then nail down the other end as well. Lead, by contrast, is so malleable it can be wrapped with bare fingers and released on every turn; it will stay exactly where it’s at. It can be pinched off with a fingernail and it won’t damage the fine edge of my tying scissors either (whereas I’d NEVER cut the much harder tungsten wire with any scissors I didn’t want to ruin in short order). I find lead so joyfully easy to work with…but the tungsten wire is quite usable too if you keep it tensioned and wrap it down with thread, and if you use true wire nippers to cut it.

The tungsten wire’s forte is its incredible thinness, period. And that goes to the question of workability too; you can apply a layer so unobtrusive your fly’s shape won’t change at all. You can think of your weight-adding exercise as “doubling the thickness of the hook’s steel,” or even less. If an application calls for that tiny amount of added weight, this stuff lets you do it.

Relative Weight

This question addresses the “which is better to use if I could use either one?” question. Given that I’d bought some to use and keep, I didn’t want to unspool a bunch of the stuff and weigh it, because I might never get it back on the spool–again it’s fine as hair and has a “springiness” to it. So I made some estimates, measurements and calculations, like so:

  • “Fine” Tungsten wire:  0.0035″ diameter, per my micrometer
  • Soft 0.010″ Lead wire: 0.010″ diameter, (about 3x the tungsten’s thickness)
  • “Fine” Tungsten wire:  9.0 grams per 25yd spool, including the spool…per a fine scale I have access to at work
  • Soft 0.010″ Lead wire: 17.0 grams per spool of undisclosed length

…so I had to figure out the length of the lead wire. I looked up the specific weight and put a stake in the ground: 36 inches (one yard) of round lead wire has a volume = 0.00283 cubic inches. That volume, per accepted properties of pure lead, has a weight = 0.52599 grams. So a yard of my lead wire should weigh 0.52599 grams, if it were 100% pure.

The 17-gram spool I weighed includes both wire weight and spool weight. I VERY ROUGHLY estimated the spool’s weight at about 4.5 grams. If that was right, then the lead wire itself weighed about 12.5 grams. Assuming I was on track, this means a spool of lead wire is about [(12.5)/0.52599] yards long (i.e., about 24 yards long). So I assumed 25 yards, same as the tunsten wire’s one-spool length. Given how companies package and market things, I think that’s a fair assumption. (And it lends some credence to my calcs thus far.)

Then…must subtract the spool weight from the tungsten wire’s measured weight too…I went with the same rough guess of 4.5 grams. So I was left with:

  •  25 yards of 0.010 lead wire weighs about 12.5 grams
  • 25 yards of fine tungsten wire weighs about 4.5 grams

So the lead wire, per length, appeared to be about 2.75 times the weight of the tungsten. Given the roughness of my estimates and the fact that the tungsten’s spool looked just a smidge larger than the lead’s, I roughed my weight conclusions in as:

  •  By length, the lead’s weight is about 3x the tungsten’s weight

And remember that the lead wire’s diameter is 3x that of the tungsten’s. This means that the two materials, by volume (i.e., by “build-up” on a hook shank) will weigh ABOUT THE SAME. (I’m sure they’re both alloys rather than being 100% pure, so the weight similarity isn’t that hard to believe.) So: If I add lead wire to one fly and fine tungsten wire to another (wrapped to the same thickness around the shank), they should sink at very similar rates.

Use Cases

The above approximations suggest that the advantage of the fine tungsten wire is not so much the weight per volume, but the amount of volume that can be used. With the lead wire, you have no choice but to build up some amount of volume. 0.010 is small but it’s not like a human hair. Probably has little use on #22 flies unless they have 3x-long shanks, and probably can’t be used on the abdomen portion of most #20 or #18 flies either.

The fine tungsten wire can be used in those cases, to add a little more weight. Again, it might be akin to adding (up to) the weight of an extra hook to a fly.

 Sources of Error

My calculations are very rough! Sources of error include:

  1. I estimated the weight of the empty spools by weighing a full floss spool and cutting that weight by a third. Very rough estimate. And I assumed the spools of both wires were almost identical. (The spool weight estimate has the potential of being the biggest source of error in my calculations, depending on how accurate my guess was.)
  2. I could find no data on the length of the lead wire, so I calculated it ASSUMING it is pure lead. I calculated the volume per yard, weighed the spool, then rounded to 25 yards (that much is probably a good assumption).
  3. I did not apply a micrometer across a sampling of points on the wires; I just measure two or three times on a single piece of wire and assumed the diameters are consistent or average out to the measurements I took.
  4. I took for granted that the tungsten wire length was as labelled (probably a good assumption).
  5. My digital scale senses fractions of a gram, but I have no idea how much error is in those low-gram measurements; this scale is typically used to measure objects weighing 50 grams to 200 grams, so 5 or 10 grams might be well out of its sweet spot. Plus it’s a work device, used by a number of engineers and not guarded or regularly calibrated as far as I know. (This source of error could be substantial as well.)

I did put an inch of each wire on a tiny “teeter-totter” made from a very thin/light toothpick carefully balanced on the edge of a knife; I fastened the bits of wire to each end of the stick with a minuscule speck of glue. The balance point after the wire was applied roughly confirmed my assumptions about weight by length, which corroborates my weight by volume conclusions to the same degree.

Final Thoughts

I’ll use the tungsten wire for the very tiniest of needs. Given my eyes and clumsy fingers, that’s likely to be sparing use. Lead is so forgiving and so easy to work with, even down to #20 hooks that have longer shanks, that I’ll still tend to reach for it first. (And for #12 hooks I’ll add 0.015 lead.) But make no mistake: the tungsten thrTad is very interesting stuff, enables things the lead can’t do, and I’m glad I have a couple of spools of it.

NOTE from J. Stockard: Michael Vorhis is the author of ARCHANGEL suspense thriller…which has some fly fishing in it…and of adventure thriller OPEN DISTANCE, based on aviation and the deep sea.

3 thoughts on “Weighted Nymphs: Tungsten Wire vs. Lead Wire

  1. Mike Cline

    Michael,
    Interesting analysis, but begs the question: Is any one weighting method more or less effective when it comes to actually catching fish? All personal preferences aside, the case against lead as a toxin in the environmental seems to have been well made from the science standpoint. Of course, such is not the case for the bureaucrats who implement bans and other silly regulations. When I use wire for weight, I use lead-free wire in all my flies for the simple reason that any lead fishing tackle is banned in Yellowstone and Glacier National Parks. Even through lead isn’t banned, but merely recommended against by Montana Fish, Wildlife and Parks, the fly shops guys here in Bozeman tell me they sell non-lead wire at a 3:1 clip over lead wire. The reason is clearly Yellowstone. Although the ban on lead is completely unenforceable when it comes to flies, it would be silly to jeopardize your Yellowstone fishing rights for the minuscule marginal increased cost of non-lead wire and slightly less weight to density. I can just imagine an overzealous park ranger slashing open my flies, taking a sample of wire for laboratory analysis on the suspicion that my flies sank too fast. That’s not beyond the realm of possibility given some of the other things the NPS is doing to its fisheries.
    Mike Cline, Bozeman, MT

    Reply
    1. Michael Vorhis

      Thanks for the input Mike. Yes, the case agaist lead has been made, although I’ve always believed that it’s mostly based on the fear of waterfowl scooping up and eating lead pellets. It’s not that lead dissolves into solution, since the inert compound lead oxide swiftly coats it. Political people are rarely astute enough to see the distinction.

      There is small fly fishing lead shot available with polymer coating. It’s supposed to address the waterfowl risk as well (and I can only assume the polymet won’t break down in digestive systems). So I’ve been figuring that as long as I coat the lead I wind with head cement, it should be safe enough. I think if I lose a fly and an animal eats it, coated lead would be the least of its worries.

      But the debates about real risk aside, you’re right that zealous lawmen may be the most tangible concern we have. Maybe you’re right that it’s safest to just use lead-free wire…although it will make the fly 30% bulkier for the same sink rate. I haven’t frequented lead-free waters a lot, but when they all go that direction I’d like to know that I don’t have to toss out all my flies.

      So if we’re comparing fine tungsten wire to lead-free “lead look-alike” wire, I believe the tungsten will be 50% heavier so will sink faster, for the same bulk. Or it will weigh the same as the lead-free at only 66% of the bulk applied to the hook.

      Reply
  2. Henry K.

    “By length, the lead’s weight is about 3x the tungsten’s weight….. And remember that the lead wire’s diameter is 3x that of the tungsten’s. This means that the two materials, by volume (i.e., by “build-up” on a hook shank) will weigh ABOUT THE SAME. ”

    Not so. Wire is a cylinder. So the relative volumes of the two wires is NOT the ratio of the wires diameter 3:1 but of the respective volumes which is actually 9:1.

    To calculate the volume of two cylinders of identical length but differing diameters, you multiply the cross sectional area of the wire (which is a circle) x the length. Since the lengths of the two wires are identical, the identical lengths cancel out; and the weights
    of the wires are proportional to their respective cross sectional areas.

    Cross sectional area varies with the SQUARE of the radius. Since the radius of the lead wire is 3X the radius of the tungsten wire, the volume of the lead wire is 9X the volume of the tungsten wire and NOT 3X the volume of the tungsten wire.

    This assumes both wires are solid and discounts the air gaps between the wires so it is an idealized calculation that assumes volumes of material will result from the wrapping of the wire.

    Reply

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