Working with Hemp Cloth for Surfboards & Fins

Creating handcrafted surf fins is a challenge. There are a variety of different ways to do it – each with their own strengths and weaknesses in terms of process difficulty, total hours, and the performance and appearance of the final product.

Wave Arcade surfboard fins have gone through a lot of different iterations. And honestly, it’s a continuous process. It’s one big f-in’ experiment.

I’ve tested lots of different materials, production methods, processes – and I think it will continue to evolve.

One of those iterations involved working with hemp cloth instead of using fiberglass.

This hemp attempt came after some majorly disappointing results with a materials & production combination that I thought was promising. More on that another time.

I found myself back to the drawing board in a big way.

I hadn’t noticed this as I was going along, but up until that point, I had been slowly straying from the original path I set out on. In itself, that’s not necessarily a bad thing – I didn’t have all the information and experience when I got started.

But at the same time – my deviations from the path seemed to take me farther and farther away from my desire to create more eco-friendly surf equipment. The fiberglass and resin required to make the fins for that latest method were a slight improvement on what’s out there, but it left a lot to be desired in terms of sustainability.

It was that thought that got me thinking about alternative cloths for glassing. I happened to arrive on hemp.

“Fiberglassing” Hemp Cloth

The hemp cloth I was working with was about 3-4oz. It was the lightest one I could find.

It’s considerably thicker than 4oz fiberglass cloth, so for the fins I was making, I decided to go with 1 single layer of hemp cloth on each side.

The first thing I noticed about the hemp cloth was that it was a pain in the ass to cut – I had to run to the store and get the sharpest scissors I could find. However, I think this was a testament to hemp cloth’s strength.

You can easily pull apart an unglassed fiberglass cloth – hemp cloth, not so much.

The next thing I noticed when I started to glass it was that folds/wrinkles do not lay down even after saturated with resin. You’ve got to iron them out beforehand.

After the resin had cured, it was time to see how the hemp cloth would sand. On my first attempt I had approached it like I would with fiberglass – do the initial coat, followed by a hot coat, all while creating a resin bead with slightly overhung glass around the fin.

The cured hemp cloth and resin was a pain in the ass to sand. After the first try, it needed to be coated with resin again. After the entire process, each fin probably required more resin than its fiberglass counterpart.

The other thing I noticed was that it added a lot more thickness to the fin than I had anticipated – this became a problem around the bases. Since I didn’t correctly account for the thickness in the wood core’s difference, the first prototypes required a lot of clean up grinding.

Finally, I had some hemp glassed fins that were ready to be surfed.

The finished appearance of the hemp was unique – you can see the weave unlike fiberglass, which is actually pretty cool, but it hides the grain of the wood, which I found less cool.

The hemp-wood fins seemed to be a bit stiffer than fiberglass-wood fins, but were still pretty light and had some good flex.

They were fun to surf, and served as a step in the right direction to a more eco-friendly fin from Wave Arcade.

Tips for Working with Hemp Cloth

If you’re thinking about experimenting with fiberglassing hemp cloth, here are some of my takeaways and tips:

• Use the lightest weight hemp cloth you can find. 3-4oz was pretty difficult to work with, I can only imagine what a thicker cloth would be like.
• Iron the hemp cloth flat before you glass it.
• Avoid laps, resin beads, or overhangs with the hemp cloth – this is going to require too much clean up and sanding.
• Vacuum bag the hemp cloth if possible, as a hand layup will require more resin.
• Price: Hemp cloth is a little more expensive than fiberglass, but you’ll use less of it and it comes in wide widths. At the same time, you’ll probably use more resin – so cost of using hemp is probably a bit higher.
• Clean up the surfaces after the first lamination round of glassing cures, then proceed with the hot coat.
  • Laminate the hemp.
  • Sand out any bumps and imperfections.
  • Clean the surface.
  • Hot coat.
• Test how much thickness it will add after laminated and hot coated – it will be more than fiberglass.
• You’re going to get a more opaque finish than you would with fiberglass.

Good luck!