Coir bristle fibre is the longest, thickest and stiffest fibre pulled from a mature coconut husk. Brush and broom makers use it because it's stiff without being brittle, resists rot and stands up to wet scrubbing. It's graded mainly on length and how well it's been combed, then on cleanliness, moisture and colour. If you buy it for brushes, the checks that matter are length distribution, stiffness, how much short fibre and pith is left in the bundle, and moisture.
For the wider picture of coir fibre types and their other uses, such as rope, mattresses and geotextiles, see coconut fibre uses and grades. This article stays with bristle and brushes.
What makes fibre "bristle"
When husks are defibred, the long, coarse fibres are combed out from the shorter, finer ones. The long fraction is bristle. The short, curly fraction is mattress fibre. One measure of the split: a husk of about 300 g yields close to 80 g of fibre, and roughly a third of that is bristle.
Measured side by side, bristle stands apart from the other grades:
| Property | Bristle fibre | Mattress fibre |
|---|---|---|
| Average length (one national survey) | About 155 mm | About 50 mm |
| Typical diameter | About 0.20 mm | About 0.12 mm |
| Breaking load per strand | 3.0 to 6.5 N | 1.6 to 5.2 N |
| Stretch before breaking | About 21% | About 24% |
| Linear density | About 48 g per km | About 19 g per km |
Two things stand out. Bristle is thicker, so each strand carries more load and bends less. And it stretches less, which is what a brush maker means by "stiff". Mattress fibre is actually stronger per square millimetre because it's finer, but it's too soft and springy to hold a brush edge.
Coir is about a third lignin, a high share for a plant fibre. Lignin gives the fibre its rigidity and colour and resists microbes. That's why coir brushes cope with water, mud and outdoor storage better than many other natural fibres.
Length isn't uniform even in good bristle. In one survey of commercial bristle, more than half the weight fell between 176 and 250 mm, with a tail down to under 25 mm and a few strands over 300 mm. The buyer's question is how much of that tail is left after combing.
How bristle is graded
There's no single world grading system, and buyers and sellers use several in parallel.
Combing grades (ties). In Sri Lanka, the basic grade straight from the mill is called one-tie bristle. Combing (hackling) it through steel combs straightens the fibres and pulls out short pieces to give two-tie, and combing two-tie again gives three-tie. Each step leaves a longer, cleaner, more even bundle. The short fibre combed out is sold separately as omat fibre. Combed bristle is what goes into brushes and other value-added products.
Length classes. Trade descriptions often call fibre 20 cm (8 inches) and longer "bristle". Brush-trade training material quotes working lengths of 9 to 18 inches (about 23 to 45 cm). National standards set length bands too. India covers bristle coir fibre under IS 9308 Part 1.
Cleanliness grades. The Philippine national standard grades coir by length, dust and total impurities:
| Grade | Length | Dust | Total impurities |
|---|---|---|---|
| CH-1 (defibred) | Over 12 cm | Under 1% | Under 2% |
| CH-2 (defibred) | Over 12 cm | Under 2% | Under 4% |
| CH-3 (decorticated) | 70% over 12 cm | Under 3% | Under 6% |
| CH-4 (decorticated) | 60% over 12 cm | Under 3% | Under 6% |
| CH-5 (decorticated waste) | 40% over 12 cm | Over 3% | Over 6% |
The same standard caps moisture at 18% and requires fibre from mature husks, between 10 and 35 cm long. Impurities here mean anything that isn't fibre: pith, husk pieces and dust.
Colour. Brown fibre comes from mature husks and is the type used for brushes. Shade varies between lots. Fibre can also be bleached or dyed for coloured brushes and mats. Colour is usually judged by eye against an agreed sample, though labs can measure it with a colorimeter.
Which brushes use it
Coir bristle turns up in almost every kind of heavy-duty brush:
- Yard, street, platform and scavenger brooms
- Floor sweeping brushes and banister (hand) brushes
- Scrubbing, deck and masonry brushes, sometimes mixed with other fibres
- Window-washing and tar brushes
- Lavatory, bottle and pot brushes, including the Japanese tawashi style
Different brushes take different qualities. In traditional brush making, floor sweeping brushes use the best long fibre, banister brushes a second quality and table brushes a third. For the roughest scrubbing, palmyra fibre is sometimes preferred to coir because it's harder.
Doormats are a slightly different story. Most coir doormats are tufted from spun coir yarn into a PVC backing, or woven, rather than set with loose bristle. If you make mats, you're mostly buying yarn, not bristle fibre.
How a coir brush is made
The basic hand process shows why each fibre property matters:
- Combing. Bundles are pulled through rows of nails or steel combs to remove pith and short fibre and line the strands up.
- Cutting. The combed bundle is cut to the length the brush needs, allowing for the part set in the stock.
- Tufting. Small bunches are folded around a U-shaped galvanised wire.
- Setting. Each tuft is driven into a hole drilled in the wooden stock and hammered tight.
- Trimming. The tops are sheared level, then the stock is sanded and finished.
How far the tuft stands out from the stock depends on the brush. Typical projections are about 8 cm for floor sweeping brushes, 7 cm for banister brushes, 6 cm for table brushes, 3 cm for lavatory brushes and 2.5 cm for scrubbing and basin brushes. Short, stiff tufts scrub. Long tufts sweep.
So length sets which brushes a lot can make. A bundle averaging 15 cm can make scrubbing and banister brushes but not long broom tufts once the folded part is allowed for. Short fibre left in the bundle becomes waste at trimming or leaves a weak, patchy face.
What brush makers check on a sample
| Check | How | What you're looking for |
|---|---|---|
| Length | Pull a hank, lay it on a board, measure or sort into length bands | Most of the weight in the band your brushes need, little short tail |
| Combing | Look along the hank | Straight, parallel strands. Two- or three-tie for brush heads |
| Stiffness | Bend a small tuft, press a bundle end on the bench | Springs back without snapping. Brittle fibre breaks at the bend |
| Pith and dust | Shake over dark paper, weigh what falls | Very little loose dust or husk pieces |
| Moisture | Weigh, oven-dry, reweigh | Within the agreed limit. Sun-dried fibre usually settles at 15 to 18% |
| Colour | Compare with an agreed sample under daylight | Even shade across the bale and between shipments |
| Smell and mould | Open the bale centre | No musty smell, no mould spots |
| Salts | Lab test if the brush is for food or sensitive surfaces | Chloride low. Survey bristle averaged about 0.35% of fibre weight |
Moisture matters for more than weight. Coir is hygroscopic, and bales packed damp can sweat in a container, especially when shipped to a cold climate. Fibre dried to around 15 to 18% avoids most of that condensation.
Set the checks you care about in the purchase contract with an agreed reference sample. With a natural fibre, a reference bundle in your factory is often more useful than a written number.
Buying bristle fibre from CVM
CVM Fiber and Industries, in Kanyakumari, Tamil Nadu, India, supplies coir bristle fibre alongside its coco peat range. If you make brushes or brooms, contact us with the brush types, the lengths you need and how you prefer it combed and packed, and we'll discuss what we can supply.
FAQ
What is coir bristle fibre?
It's the long, thick, stiff fraction of coconut husk fibre, separated from the shorter mattress fibre by combing. In one survey it averaged about 15 cm long and 0.2 mm thick, with much of the weight between 18 and 25 cm. It's used mainly for brushes, brooms and heavy twine.
Why is coir used for brushes?
It's stiff but not brittle, holds its shape when wet and resists rot because of its high lignin content. It's also a by-product of coconuts already grown for food.
What do one-tie, two-tie and three-tie mean?
They are combing grades. One-tie is bristle straight from the mill. Combing it gives two-tie, and combing again gives three-tie, each longer, straighter and cleaner. The combed-out short fibre is sold as omat fibre.
How long should bristle fibre be for a broom?
It depends on the tuft length. Floor sweeping brushes need about 8 cm of tuft showing, so the fibre must be long enough to fold into the stock and still reach that. Scrubbing brushes need only about 2.5 cm showing.
What moisture content should coir bristle have?
Sun-dried coir usually settles at 15 to 18% moisture. The Philippine grading standard sets a maximum of 18%. Damp bales can sweat in shipping containers and grow mould.
Are coir doormats made from bristle fibre?
Mostly not. Most coir doormats are tufted or woven from spun coir yarn. Bristle fibre goes mainly into brushes and brooms.
Can coir bristle be dyed or bleached?
Yes. Natural brown is the standard, but coir can be bleached to a lighter shade or dyed for coloured brushes and mats. Agree the shade against a physical sample.