Advances in Materials and Manufacturing in Ultralight Backpacks: A Technical Review and Case Study

Nice write up, Ryan.

In response to Section II of this article, I would appreciate it if you could say a few words about full woven Spectra, the trade name of a woven UHMWPE fabric that was used for packs by various makers including McHale, Kelty, and Cilo Gear. It doesn’t fit into the four categories of fabrics listed in this section. What were its advantages and disadvantages, and why did it disappear from pack manufacturing? (It wasn’t astronomically expensive when first being used).

Jon – Spectra exited the outdoor market because the demand for the outdoor fabrics they were making was so small. Their body armor and industrial fabric divisions were much larger.

Their fabric was indeed a woven UHMWPE with PU-based coatings (although they made uncoated fabrics that were used in some packs as well – but they suffered from poor water resistance and bias stretch).

Do you mean with molecular bonding good old High Frequency welding (which is also on the molecular level)?

I have not seen Aluula Graflyte. But I have used enough Challenge Ultra over the years to think it can only be an improvement.

A current 100% woven UHMWPE fabric available for traditional construction is the Technoforce Steel from Teijin. It is used by Yamatomichi for pockets only, as the coating is not water resistant enough for the pack body. I weighed a sample and found it lighter than Ultra 100X, which is quite remarkable

Interesting read.

Can you estimate the possible savings in weight of some current available packs, both unframed and framed?

E.g. wat would it do to the weight of the Seek Outside packs (not ultralight but just light).

Ryan,

Thanks. So it was a decision by the makers of Spectra to withdraw the fabric from the outdoor gear market. I never saw anybody mention that.

I have a couple of McHale packs in full woven Spectra. An 80L S-Sarc that is made with uncoated Spectra wets out from snow almost instantly, but even after about 25 years there’s no bias stretch in the fabric. Ditto for a 30L Windsauk, no bias stretch there, either.

In fact, those packs are both in excellent shape, with that “hiker trash” look that only undyed dirty white Spectra can confer, lolz!

Aluula is a completely different material. It works very well in my gravel bike pannier bags and I expect that it will become more common in packs. Thanks to BPL, we can know a little more about it.

Best,
Jon

Marc – good question – HF welding only works for polar molecular bonding (e.g., PU/TPU) – it won’t work on UHMWPE, which requires a nonpolar bonding chemistry, not possible with RF/HF.

“HF welding only works for polar molecular bonding (e.g., PU/TPU) – it won’t work on UHMWPE, which requires a nonpolar bonding chemistry, not possible with RF/HF.”

You kids with your own slang. I grok that these fabrics won’t work at either pole…and that they smell bad (pee yew). But I assume that for mid-latitudes, the uhm a binga bing bang whumpfa Pee eee  kicks in and they’re fine.

however I haven’t actually read the article.

I like how Ryan is trying to keep the controll pack anonymous, although it’s clearly the Durston Wapta 30 in Size L with Hipbelt, Sternum strap and top strap (540g). After all, there aren’t many 30 L Aluula backpacks around yet.