Back in the old days, the covering of Greenland kayaks was mostly done with seal skin. H.C. Petersen writes in his ‘Instruction in Kayak Building’: “…when the seal population of Greenland began to decline at the beginning of the present century, it became difficult for many hunters to get hold of the required number of suitable kayak-skins. More and more hunters have therefore started to cover their kayaks with canvas or duck.”

Modern Fabrics

With the invention of modern materials, polyester and nylon (polyamide) became the two most used materials because of their lightness, strength, abrasion resistance, and rot resistance. Both materials have their pros and cons.

Polyester

Polyester is a little better in UV resistance, but it’s less abrasion-resistant than nylon, and most coatings will stick to it without a problem. It can be tricky to work with because it will not stretch like nylon, so it’s harder to apply it nicely to follow kayak curves, and you could get wrinkles—but this is resolved by shrinking it with an iron. That said, if you look for polyester fabric, you should find one that is not preshrunk!

Polyamide

To be precise, ballistic nylon. It was developed by the DuPont corporation as a material for bulletproof vests in WWII, with great abrasion and puncture resistance. It’s nice to work with as it follows kayak curves because of its stretchiness. Next to greater abrasion resistance, this stretchiness is actually the second important reason why I chose nylon. It will simply better absorb hits if struck with something. On the downside, it’s hygroscopic, so it can relax a little in humid and cold weather, so you get loose skin in these conditions. This effect mainly disappears over time, but to prevent this, it’s important to tighten it correctly around the frame, even sewing the fabric when wet if needed. Not every coating will stick to it, but oil-based urethanes will do the trick, and most of these will have good UV resistance too. So, if applied correctly, these downsides can be avoided.

The USA has more skin-on-frame kayak builders, so more choice of materials too.
Skin material was actually my main problem because I wanted to find ‘my skin,’ and Europe was the perfect place where you don’t have to look for it!

Tests

After too many emails with various fabric companies and too many fabric samples, I finally found it. I wanted to provide all my tests of different fabric types in this blog at first, but I changed my mind because it would take an eternity, and most materials were not so good, so I’ll try to explain the results briefly.

I tested polyamide woven fabrics. So what’s exactly ballistic nylon? Polyamide fabric woven with basket/panama type of weave and yarn that is smooth. Ballistic nylon from one German store is strong but has a very loose weave, so once you start tightening it around the frame, you will get large pull holes that can be sealed, but with more applied strength, these holes open even more, and this is something that concerns me. I’ve tested one more similar German fabric with nearly identical results. Further, Cordura classic (developed and trademarked by DuPont) polyamide 6.6 fabric woven with plain weave is a superb material that is very similar to ballistic in strength and abrasion resistance, but the biggest problem is that it’s made with ATY (air textured yarn), so the surface is a little fluffy or hairy, and this creates problems during urethane coating, so you can’t get a smooth surface.

Finally, the fabric that I’ve found to be the best for my needs is nylon 66 fabric with durable rib weave. Depending on the batch, it has a width of approximately 165 cm and weighs approximately 270 g/m², and is woven with yarn of 470dtex. Dtex? In short, the weight of fabric yarn. So if compared to, let’s say, 1100dtex fabric, does it have much less strength? Yes, if both materials have the same number of threads/cm, but this is a tightly woven fabric with the most threads/cm of all fabrics that I’ve tested. Having said that, its tensile strength for warp/weft goes over 4000N/3000N (ISO 13934-1), which is actually stronger than Cordura classic 1100dtex in 260 g/m² (warp/weft over 3200N/2300N ISO 13934-1) and similar strength to one German ballistic nylon that I’ve tested in 940dtex / 290 g/m² (warp/weft over a little bit over 4000N / ISO 13934-1). Why nylon 66? Nylon 6 and 66 are the two most commonly used synthetic polymers known as polyamides. Nylon 66 is 33% more resistant to abrasion than nylon 6, it has a higher melting point, higher heat deflection temperature, lower water absorption rate, and better chemical resistance to acids.

Because of the tighter weave, this fabric can be pulled hard during tightening of the fabric with thread and while sewing. Pull holes? Yes, it’s something that’s normal because the fabric is not fixated with coating yet. You will get acceptable pull holes, and most importantly, the holes will not be bigger if extreme force is applied. I always use sealer for these holes anyway. It’s hard to describe the details here with words, but I’ll explain this more in my ‘sewing the skin’ blog with detailed images provided.

Speaking about colors, I do not know how it will accept acid dyes because I’m not using ones. Due to more threads per cm of this fabric, I didn’t want to take any risks with the acid dyes. Because of applying it diluted in water, before urethane covering, there is possibility of urethane not protruding well into fabric and cause delamination of it. That’s why I cover the skin with earth pigments only.

Update
I finally found a great aliphatic urethane coating, so you may want to check out my ‘New skin on frame coating day’ blog.