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How Cluster Lashes Are Made: From Fibre to Tray

How cluster lashes are made comes down to ten repeatable steps: a synthetic fibre is extruded, cut to length, tapered at the tip, heat-set into a curl, fanned into small bundles, bonded at the base, then placed on a tray. The fibre is almost always PBT (polybutylene terephthalate), a thermoplastic. Length is quoted in millimetres (most clusters are 8–16 mm), fibre thickness in millimetres (0.06–0.15 mm), the fan size in strands (20D to 100D), and the curl in a letter (J to U).

The short answer

A cluster lash is a small fan of several individual fibre strands bonded together at one point so it can be applied as a single piece. Making one is a sequence, not a single operation: fibre is produced, cut, tapered, curled, grouped into a fan of a fixed strand count, glued at the base, and mounted on a tray or strip. Every step has a number attached, and those numbers — fibre diameter, length, curl letter, strand count and pieces per tray — are what you approve on a sample and repeat on a reorder.

What a cluster actually is

Confusion over how cluster lashes are made usually starts with the word itself. A cluster is not one thick lash; it is several thin strands gathered into a fan. The strand count is written with a D suffix, and it is the number a buyer should specify on every order.

20D–30D — a lighter fan for a natural, everyday look
40D–50D — a medium fan, the most common retail default
60D–80D — a fuller fan for a wispy or volume look
100D — the densest common fan, used for a dramatic effect

Fibre: where it starts

Cluster and strip lashes are almost always made from PBT (polybutylene terephthalate), a thermoplastic fibre chosen because it holds a heat-set curl, keeps its shape, and feels light. PBT does not expire, but its curl can relax over time, so finished lashes are stored cool and dry, away from direct sunlight and humidity. Fibre arrives on large spools and is then cut to the lengths your range needs.

Step by step: from fibre to tray

The exact equipment differs by factory, but a real production line runs through the same ten stages. This is the sequence to ask a maker to walk you through.

Step	What happens	Why it matters to the buyer
1. Extrusion	PBT resin is extruded into continuous fibre of a set diameter.	Fixes the fibre thickness you are buying (0.06–0.15 mm).
2. Cutting	Fibre is cut to the lengths the range uses, commonly 8–16 mm.	Sets the length printed on the tray.
3. Tapering	The tip of each strand is tapered to a fine point.	A blunt tip reads as cheap and feels stiff.
4. Curling	Strands are wound on a rod and heat-set so the curl becomes permanent.	The rod diameter sets the curl; a thin rod gives a tighter curl.
5. Sorting	Curved, kinked or off-colour strands are pulled out by hand.	Removes the strands that would cause visible drop-out.
6. Aligning	Strands are laid in a line and held in place on tape.	Decides how even the fan looks at the base.
7. Fanning	A fixed number of strands (20D–100D) is gathered into each fan.	This is the strand count you approve.
8. Bonding	Adhesive is applied at the base to lock the fan into one piece.	A weak bond is the number-one cause of clusters splitting.
9. Setting	Bonded fans are dried and cured so the base holds.	Controls how the base flexes when applied.
10. Traying	Fans are placed on a tray or strip and packed.	Sets pieces per tray, rows and the retail format.

The curl and how it is set

The curl is not a styling choice made at the end; it is set during manufacture, when the fibre is wound on a rod of a given diameter and heat-set. Curls are named by letter, and each letter is tied to an approximate angle. The figures below are the trade convention, not a fixed standard, so confirm the exact angle on a sample.

Curl	Approx. angle	Typical use
J	≈ 30°	Very natural, straight-lash customers
B	≈ 45°	A soft lift, inner corners
C	≈ 55–60°	The worldwide retail default
CC / D	≈ 60–70°	An open-eye, fuller look
D	≈ 70–80°	Dramatic lift
U / DD	≈ 80–90°	The tightest curl, doll-eye effect

Band, base and assembly

A cluster's base is the part a customer notices first and complains about most. On a fan, the base is the bonded point that holds the strands together; on a tray applied to a strip, there is an additional band running along the spine. A base that is too stiff will not sit flat; one that is too soft will split when the cluster is picked up with tweezers. Ask which base a quote refers to, and get a physical sample of that exact type before approving a run.

Tray and count: the numbers buyers actually reorder on

How many clusters a customer receives decides the price per use, so the tray configuration must be stated, not assumed. DIY cluster trays commonly hold 60 to 200 pieces across 6 to 12 rows, and a fan of 40D–50D at 10–14 mm is the usual retail centre. Fix pieces per tray, rows, and the length mix (single-length or mixed 8–16 mm) on the order, because all three change the landed cost and the reorder.

Pieces per tray — commonly 60, 96, 120 or 144
Rows — commonly 6 to 12, depending on fan width
Length mix — single length, or mixed 8–16 mm
Strand count — 20D to 100D, stated per line

How to check a maker's output

Once you know the process, the checks that separate a good run from a weak one are quick.

Fan consistency — open ten fans; the base should look identical across all ten
Curl uniformity — sight down a row; the curl should not vary between fans
Bond strength — pinch and flex a fan base; it should not split or shed strands
Tip quality — a tapered, pointed tip, not a blunt or melted one
Count accuracy — count one row yourself against the stated count

What to ask before you order

A maker that can answer these without checking is one that controls its own production. If the answers change between messages, treat that as a signal.

Is the fibre PBT, and what diameter is used for this line?
What rod diameter sets the curl for each letter you offer?
Is the fan bonded in house or bought in?
What is the strand count, pieces per tray and row count?
Can the run be made in-house from fibre, or is it assembled from a bought-in fan?

Next step

If you are sourcing clusters, the fastest way to judge a maker is to see the staging step and hold a sample of the exact fan you intend to buy. Browse the cluster lash catalogue, add your quantities to an inquiry list, and we will quote by quantity — or write to [email protected] with the fibre, curl, length, strand count and pieces per tray you need.

About this guide

Written by the VEN Lash sourcing team with AI-assisted drafting and reviewed by our production and quality staff. Figures are standard lash-trade specifications and are confirmed for your own order in the written quotation. Last checked: 11 October 2026.