How Recycled Plastic Becomes a Surfboard Fin | Indorider

Ours aren't.

Our FCS-1 recycled plastic fins (soon we will manufacture recycled plastic Future Fins) are made from plastic waste collected directly from beaches and rivers — much of it through our partnerships with Sungai Watch. We think that's worth explaining properly, because the process of turning trash into a piece of performance surf equipment isn't obvious, and most brands don't bother showing their working.

Here's exactly how it happens, start to finish.

Step 1: Collection — Getting the Plastic Out of the Water

It starts on beaches and riverbanks, not in a factory. Through clean-up partners like Sungai Watch in Indonesia and a wider network of charities, volunteers physically remove plastic waste from waterways before it breaks down further or reaches the open ocean.

This matters because once plastic fragments into microplastics in open water, it's essentially unrecoverable — it's ingested by marine life, enters the food chain, and stays in the ecosystem indefinitely. Catching it upstream, while it's still whole enough to collect, is the only realistic way to actually remove it from circulation.

The waste collected is mixed: bottles, packaging, fishing gear, and general litter. It has to be sorted before it can become anything useful.

Step 2: Sorting and Cleaning

Once collected, the plastic is sorted by type. Not all plastic can be recycled the same way — different polymers melt at different temperatures and behave differently under pressure, so mixing them produces a weak, unreliable end material.

For fins specifically, we need a consistent, high-density plastic that can be melted down and reformed into a rigid, hydrodynamic shape without becoming brittle. That means sorting out contaminants — organic debris, other polymer types, metal, glue residue — and cleaning what's left thoroughly. Any residual salt, sand, or grime left in the material weakens the finished product, so this stage is slow and manual by necessity.

Step 3: Shredding and Granulating

The sorted, cleaned plastic is shredded into small flakes, then further processed into uniform granules or pellets. This step transforms bulky, irregular waste — a crushed bottle, a torn fragment of packaging — into a consistent raw material that behaves predictably in manufacturing.

Uniformity here is what determines the quality of everything downstream. Inconsistent granule size leads to air pockets, weak spots, and fins that flex unevenly or snap under load — the last thing you want mid-session.

Step 4: Melting and Moulding

The granulated recycled plastic is melted down and injected into fin moulds under heat and pressure — the same basic principle used for standard injection-moulded fins, just with reclaimed material instead of virgin plastic pellets.

This is where the fin actually takes shape: its foil, its flex pattern, its base plug fitting (FCS- and soon FUTURE compatible). Getting the moulding temperature and pressure right is critical — too cool and the material doesn't bond properly, leaving weak seams; too hot and the recycled plastic can degrade, losing structural integrity.

Step 5: Cooling, Trimming, and Quality Control

Once moulded, each fin is cooled under controlled conditions to prevent warping. Excess material — the flashing left over from the mould — is trimmed by hand, and each fin is checked for consistency: correct flex, no air bubbles, a clean fit into the fin box.

Recycled material is inherently less predictable than virgin plastic, since the exact composition can vary slightly between batches depending on what was collected. That means quality control matters more here than it does with standard fins — every batch gets strength checked rather than assumed to be fine.

Step 6: Ready to Ride

The finished fin is a fully functional, performance-ready piece of surf equipment — built to the same standard as any fin on the market, just made from plastic that was, not long before, floating in a river or washed up on a beach.

Does Recycled Plastic Perform as Well?

Short answer: yes. A well-manufactured recycled plastic fin performs comparably to a standard injection-moulded fin — similar flex, similar drive, similar durability. The material science is well established at this point; recycled high-density plastics can be engineered to match the performance characteristics surfers expect.

The bigger difference isn't in the water. It's in what didn't happen to make the fin: no new petroleum extracted, no virgin plastic manufactured from scratch, and a measurable amount of waste physically removed from the ocean's supply chain instead of added to it.

Why This Process Matters More Than the Marketing

A lot of "eco" surf products lean on vague language — "ocean-inspired," "sustainably minded" — without explaining what actually happens behind the scenes. We'd rather show the process, warts and all: it's slower, messier, and more labour-intensive than manufacturing with virgin plastic. That's exactly why most brands don't do it.

It's also why we donate 5% of every sale — including every set of fins — to the clean-up organisations that supply part of the raw material in the first place. You can read more about where that money actually goes on our sustainability page.

Try a Set for Yourself

If you're due a fin replacement, it's a small, easy switch with a real impact behind it. Check out our FCS-1 recycled plastic fins, and while you're there, take a look at our other eco surf equipment — including our 100% beeswax surf wax — if you want to take it further.

Indorider is a UK-based sustainable surf brand. We make handcrafted surfboards in Bali, eco surf equipment, and organic cotton apparel — and we donate 5% of every sale to ocean and river clean-up charities.