Tungsten vs Brass Beads for Fly Tying

September 25, 2026

Tungsten gets a nymph down fast without a big head. Brass still earns bench space in shallow water and on big batches. Here is how we pick in Ilwaco.

By Josh Phillips · Spawn Fly Fish, Ilwaco, WA

A bead does two jobs on a nymph. It adds weight, and it sets the head shape.

Material decides how fast the fly drops. Hole style and diameter decide how it seats on the hook.

The question we get most at the bench is tungsten or brass. Same pattern. Different sink. Different price.

We stock both and tie with both. The right pick depends on depth, current, and how many flies you expect to leave in the alders.

Tungsten vs brass: density and sink

Tungsten is about twice as dense as brass. Hold one of each at the same size in your palm. The tungsten feels like a different object.

That gives you two ways to use it:

Same diameter: tungsten sinks faster.
Same weight target: drop one size in tungsten and keep a tighter head.

In fast or deep water the smaller head matters. The fly reaches the fish without looking like a marble with legs.

Brass sits in the middle. Enough weight for most trout nymphs in moderate water. Slower to the bottom than tungsten of the same size.

Glass and lead still show up in catalogs. Glass is about color, not sink. Lead eyes and dumbbells belong on streamers. For round nymph beads, the daily choice is tungsten or brass.

Spec note: tungsten is about 19.25 g/cm³. Brass runs about 8.4 to 8.7 g/cm³. Call it 2.2 to 1.

When tungsten wins

Reach for tungsten when:

The water is deep or pushing hard.
You want depth without a bigger head.
You fish jig nymphs or Euro-style drifts and need a compact, heavy head.
You keep drifting above the fish on brass and need one more step of sink.

On our bench, tungsten is the default for winter steelhead nymphs, the faster lower Columbia tributaries, and any fly that has to get down on a short line.

When brass still wins

Brass is not a downgrade. It is the right tool when:

Water is shallow or slow and a heavy bead digs in or hangs up.
You are tying a big batch of teaching flies or lost-fly ammo and cost matters.
The pattern wants a little flash and a moderate sink, not a rocket.
You are matching an older recipe written around a brass Cyclops head.

If the fly plows or ticks bottom every cast, drop a tungsten size or switch to brass. Do that before you blame the tippet.

Bead designs

Round and slotted beads cover most nymphs. Color and plating change the look, not the sink.

Slotted beads open to one side and seat on jig hooks and many straight shanks. Through-hole beads slide over a standard eye. Seat the bead flush behind the eye and leave the thorax room to work.

Pick material first. Then pick the hole style that fits the hook. We will cover slotted vs through-hole in the next guide.

Specialty shapes change the profile and where the weight sits on the shank. Footballs, Fathoms, cones, and dumbbell eyes each earn a place on specific patterns. Use them when the fly calls for that silhouette, not because the jar looks good.

Quality and sourcing

Not all tungsten is equal.

Cheap packs run inconsistent diameters, rough holes, and plating that chips after a few fish. That wastes time at the vise and throws off any size chart.

Good tungsten holds size, sits square on the hook, and keeps its finish. We buy for the patterns we fish out of Ilwaco, not to fill a brand list.

Brass density does not vary much. Physics is physics. Hole cleanliness and finish still vary. A clean hole seats in one push and saves thread.

Size to hook

Start here. The bead should sit flush behind the eye without swallowing the thorax. If it looks oversized, it is.

Bench rule: same millimetre in tungsten weighs about twice what brass does. If the brass version already fished right, drop one size when you move to tungsten. That is a starting point, not a law. Check the balance on the hook.

Bench rule: When replacing brass, start about one stocked bead size smaller in tungsten for a similar weight feel.

Try 2.8 mm tungsten in place of 3.3 mm brass. Keep the hook size unchanged for that first comparison.

This is a starting trial, not an exact weight conversion. One size smaller can still be heavier; two steps may be closer.

One step means the next smaller listed round size: 3.8, 3.3, 2.8, 2.4, 2.0, 1.5 mm.

Hook numbers are starting ranges. Wire thickness, bend, barb, hole, and slot can change the fit. A larger hook number means a smaller hook.

On small screens, scroll across for every column.

Start with the hook. Adjust the weight at the bench.
Bead mm	Hook range (trout nymph)	Brass feel	Tungsten feel	Swap tip
1.5 mm	#18-22	Light head for a small midge.	More weight within the same tiny head.	No smaller round size appears here. Keep brass if its weight already suits the drift.
2.0 mm	#16-20	Light small-nymph head.	More weight without adding head width.	From 2.0 mm brass, start with 1.5 mm tungsten. Check that the smaller hole clears the hook.
2.4 mm	#14-18	Moderate weight for a small trout nymph.	Heavier option at the same head width.	From 2.4 mm brass, start with 2.0 mm tungsten. Compare weight before tying the batch.
2.8 mm	#12-16	Moderate weight with a fuller head.	More weight for a deeper or shorter drift.	From 2.8 mm brass, start with 2.4 mm tungsten. It can still weigh more than the brass bead.
3.3 mm	#10-14	Larger head with less weight than tungsten.	More weight for a large nymph.	From 3.3 mm brass, start with 2.8 mm tungsten. Compare 2.4 mm too if weight remains too high.
3.8 mm	#8-12	Large head with moderate weight for its size.	Heavy head for a large nymph or small streamer.	From 3.8 mm brass, start with 3.3 mm tungsten. Compare 2.8 mm too if weight remains too high.
5.5 mm nominal Spawn football Specialty	Outside this trout chart. Fit the actual hook or shank.	No brass equivalent assigned.	Shaped tungsten head. Listed bead weight: 0.4 g.	Choose for shape and fit. A nominal 5.5 mm football is not a 5.5 mm round-bead equivalent.
8-9 mm nominal Spawn Fathom Specialty	Outside this trout chart. Fit the actual hook or shank.	No brass equivalent assigned.	Large slotted head. Listed weights: 8 mm, 4 g; 9 mm, 6.2 g.	Select the required weight and fit. Do not extend the trout hook ranges or one-step rule to these sizes.

Reading the table: The first six rows cover round trout-nymph beads. The final two cover specialty shapes and sizes. Feel describes relative bead weight and intended use. It does not promise a depth or descent time.

Equal-weight estimate: For geometrically similar solid beads, tungsten diameter is about brass diameter × 0.76. This uses the cube root of the brass-to-tungsten density ratio. It ignores real holes and alloy differences.

In that model, 3.3 mm brass corresponds to about 2.5 mm tungsten. A 3.8 mm brass bead corresponds to about 2.9 mm tungsten.

These are calculated estimates, not measured products or stock sizes. Equal bead weight also does not guarantee the same drift.

Bench check: Put ten matching beads in a tared cup on a gram scale. Divide the total by ten. Repeat with the proposed replacement. Use enough beads to give a stable reading on your scale.

Then fit one on the intended hook. Leave the eye open, preserve the hook gap, and leave room for the thorax.

Starting hook ranges adapt J. Stockard's bead guide. The 3.3 mm row uses its adjacent 3.2 mm class. The 3.8 mm range is narrowed from #6-12 to #8-12 for trout nymphs. These are editorial starting points, not verified fits for every Spawn bead and hook.

Specialty weights come from Spawn's football bead and Fathom bead product pages, checked 2026-09-10. They are maker-listed weights, not measurements from this pass.

Comparing your options

The table below is the short version. Then shop the bead collection for the finish and hole style your pattern needs.

Compare the same diameter, shape, and similar holes. Keep the hook, dressing, and rig consistent. On small screens, scroll across for every column.

Pick the weight your drift needs.
Criterion	Tungsten	Brass	Pick when
Sink at the same diameter	More weight; usually reaches depth sooner.	Less weight; usually drops more slowly.	Try tungsten when the fly stays above your target depth. Try brass when it drags bottom.
Size for similar weight	A smaller bead can carry similar weight.	Needs more material volume for the same weight.	Start one stocked size smaller in tungsten. Check the weight and hook fit before tying a batch.
Cost per fly	Usually costs more per bead.	Usually costs less per bead.	Compare pack price divided by bead count. Multiply by the number of beads in each fly.
Water type	Useful in deep runs, strong current, and short drifts.	Useful in shallow runs, soft seams, and slower water.	Choose for depth and current. Cold water alone does not call for a heavier bead.
Head silhouette	Adds weight without increasing head diameter.	Keeps a larger head lighter.	Use tungsten for compact weight. Use brass when the pattern needs a larger head with less weight.
Volume-tying economics	Higher bead spend across a large batch.	Lower bead spend for classes and repeat ties.	Fit five beads before committing to a batch. Compare cost per usable bead, including rejects.
Durability and finish	Inspect coating, roundness, and hole edges.	Inspect the same features. Exposed brass can tarnish.	Reject burrs or damaged coatings. Material alone does not establish finish quality.
Euro and jig fit	Compact weight suits many tight-line nymphs. A suitable slot can clear a jig bend.	Can suit lighter nymphs if the hole fits the hook.	Match the hole to the actual hook. Tungsten alone does not guarantee a jig fit or point-up drift.

Density: Pure tungsten is about twice as dense as brass: approximately 19.25 g/cm³ versus 8.4-8.7 g/cm³. The material ratio is about 2.2-2.3:1. It is not a sink-speed multiplier.

Finished bead weight also depends on alloy, hole volume, and shape. Fly dressing, tippet, current, and rig tension affect the descent.

Head width: Matching diameters and shapes give the same head width. Tungsten gives a smaller silhouette only when you choose a smaller bead.

Fly tying bead FAQ

Are tungsten beads better than brass for fly tying?

Better for sink and for a smaller head at the same weight. Not always better for the water. Shallow or slow water often fishes better on brass or a smaller tungsten.

How much faster do tungsten beads sink?

Tungsten is about twice as dense as brass. Same diameter, faster drop. Or use a smaller tungsten bead to match brass weight and keep a tighter fly. We do not quote sink rates in seconds. Current, tippet, and the rest of the fly change that number too much.

What size tungsten bead should I use for my hook?

Start with the chart on this page. 1.5 to 2.0 mm for midges, 2.4 to 2.8 mm for standard nymphs, 3.3 to 3.8 mm for big nymphs. The bead should sit flush behind the eye without eating the thorax. If it looks oversized, drop a size.

When should I still buy brass beads?

Shallow water, soft drifts, and big tying batches where cost matters. Brass is also fine when an older pattern was built around a brass head and already fishes well.

Slotted or through-hole with tungsten?

Match the hole to the hook. Slotted for jig hooks and many straight shanks. Through-hole for a standard eye. Material and hole style are separate decisions.

Why do cheap tungsten beads feel inconsistent?

Soft plating, rough or off-round holes, and size drift between packs. That shows up as beads that will not seat and flies that do not match. Buy packs that hold diameter and finish.