Castor Oil-Derived Bristles

The Challenge

Toothbrush bristles need to do a lot. They need to be soft enough for daily brushing, strong enough to clean effectively, hygienic enough for repeated use, and durable enough to work with sonic vibrations without losing their shape too quickly.

In oral care, finding a bristle material that performs well and has a lower environmental impact is not simple.

Existing Options

Most toothbrush bristles are made from conventional nylon or polyester because they are reliable, flexible and durable.

There are also natural animal-hair options, such as boar hair or horse hair. While these may be closer to plastic-free, they come with their own trade-offs. They are animal-derived, not vegan, can vary in texture and softness, may hold moisture more easily, and are not ideal for the consistency and hygiene needed in a sonic toothbrush head.

Our Choice

Crescent Nest bristles are made from castor oil-derived bio-based nylon.

Castor oil comes from the castor bean plant, a hardy crop known for growing in dry conditions and less fertile soils. Because it can grow where many food crops may not thrive, it can help reduce pressure on prime agricultural land or land better suited to food production and tree growth.

Castor bean plants also have a relatively fast growing cycle. Some agricultural estimates suggest that, with two growing cycles per year, castor plants can absorb around 34.6 tonnes of carbon dioxide per hectare, roughly the size of a sports field.

The oil is then processed into a durable bio-based nylon filament, giving the bristles the familiar soft feel and cleaning performance people expect from a quality toothbrush.

How Castor Oil Becomes Bristles

The journey from plant to performance involves six carefully controlled steps:

1. Harvest & Press — Castor beans are collected and cold-pressed to extract their natural oil. No harsh solvents are used at this stage; just mechanical pressing that keeps the process as clean as possible.
2. Refining — The raw oil is filtered and purified to remove plant matter and impurities. This step uses water-based processes rather than heavy chemical treatments, producing a clean, stable oil ready for the next stage.
3. Bio-Based Building Blocks — The refined oil's fatty acids are converted into two plant-based components: decamethylenediamine and sebacic acid. Both are derived entirely from the castor plant, and together they form the building blocks of PA1010.
4. Polymerisation — The two components are joined together in a controlled reaction to form PA1010, a 100% bio-based nylon. PA1010 is valued for its flexibility, strength and chemical resistance, making it well suited for the demands of daily brushing.
5. Filament Extrusion — The nylon is melted and drawn through fine nozzles to create long, ultra-fine filaments. This process shapes the bristles to precise diameters without the need for harmful plasticisers or chemical softeners.
6. Bristle Finishing — The filaments are tapered, end-rounded and softened to the exact profile needed for gentle but effective cleaning. They are then ready to be set into the brush head.

How Bristles Are Anchored to the Brush Head

Once the bristle filaments are finished, they are tufted into the bamboo brush head using a process called anchor tufting, a well established method used in quality toothbrush manufacturing. No glue is used at any point.

It works in three stages:

1. Drilling — Precise holes are drilled into the bamboo head in the exact pattern needed for the bristle layout. Each hole is sized to accept a single tuft of filaments.
2. Tufting — A bundle of bristle filaments is folded in half and fed into each hole by the tufting machine. This fold doubles the filaments, creating a dense, even tuft at the surface.
3. Anchoring — A small copper anchor clip is pressed into the base of each hole, locking the folded filaments firmly in place inside the bamboo. No glue, no adhesive, no surface bonding of any kind.

The result is bristles that are mechanically secured from within the brush head itself. The copper anchor sits out of contact with your mouth and holds the tufts firmly against the forces of everyday brushing, including the vibrations from sonic use.

This is the same fundamental tufting method used by quality toothbrush manufacturers around the world, and it is why well made brush heads hold their bristles reliably over time.

See it in action from inside our factory:

No Nasty Chemicals

One of the reasons we chose castor oil-derived PA1010 nylon is how it is made. Unlike many conventional plastics that rely on fossil fuels and heavy chemical processing, the castor oil pathway avoids several of the more harmful inputs common in synthetic bristle production.

There are no petroleum-derived precursors, no bisphenols, and no phthalate-based plasticisers used in the formation of the bristle material itself. Both components of PA1010 come from the plant, not a refinery.

That said, manufacturing at scale is never entirely free of chemistry. Cleaning agents and process aids are used in controlled industrial settings, and we continue to ask our supply chain partners for transparency on the full picture. We will share more as we learn more.

Not Perfect. Better.

Castor oil-derived bristles are not a perfect solution. The plant oil still needs to be processed into a bio-based nylon, and like most modern toothbrush bristles, they are not home compostable.

But within today's oral care industry, we believe they are one of the better bristle materials currently available, especially when compared with standard fossil-fuel-based nylon or polyester.

For us, sustainability is about making thoughtful improvements where they genuinely work: better materials, less waste, strong performance, and a toothbrush system designed to last longer.