Thursday 15 October 2015

Better, More Flexible Eyeglasses Through Materials Science and Digital Fabrication


According to statistics, more than half of you are reading this with eyeglasses on the front of your face. Let's talk about how they're made.
Eyeglasses frames are typically either metal, with titanium being the trendiest these days, or plastic. Of the plastic frames, injection molded are the cheapest (and cheapest-looking), using nylon-based plastics that can grow brittle with age; most fashion-conscious brands these days eschew injection molding and make their frames from sheets of cellulose acetate, which are laminated into blocks, then milled or stamped into shape.
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Cellulose acetate is fairly flexible stuff and can be colored, which is why it's become the go-to material. But now a new brand calledAspire Eyewear, launched just this year, has concocted a proprietary nylon blend that they reckon is better. Called SDN-4, the stuff is milled like acetate is—in Aspire's case, CNC-milled—but can be made lighter and thinner.
Here's how flexible the stuff is:
Obviously the super-twisty shots aren't practical, as if there were lenses in those shots they'd break, but you get the idea. "SDN-4 is extremely lightweight, pliable, strong, and resistant to heat and UV exposure," the company writes. Acetate, in contrast, is susceptible to heat; when I first started wearing eyeglasses as an adult, a friend who was a lifelong spec-cy advised me not to leave acetate glasses in a hot car, warning that they would deform.
Aspire sent me a pair of their glasses to try out (the "Powerful" model), and the first thing I did was squeeze them flat, emulating what would happen if they were tucked in a jacket pocket without any protective case:
They went flat without complaining. But while the company claims the material's memory will cause it to spring back into shape, the pair I tested didn't, at least not right away:
Still, I found it was simple enough to re-introduce the curve with my fingers, as below, and they then kept that shape.
Impressively, you'd swear by looking at them that the SDN-4, which is what the fronts of this model are made of, was the same stainless steel that the temples are made of:
Its only up close and in good light that you can tell the materials apart.
My biggest gripe with the two pairs of metal eyeglasses I own is that I must regularly dig out that tiny screwdriver and re-tighten the hinge screws. Aspire's glasses feature a screwless hinge design:
However, I'm not sure how to adjust them, or if there even is any possibility of user-adjustability. I've been testing them for just over a month, and I can't recall if they arrived like this or if this has recently developed, but the right hinge is looser than the left hinge for the first 10 degrees or so. This is not noticeable while wearing the glasses and doesn't have any performance drawback that I can see, but I was asked to review the glasses, hence the fine-toothed comb.
The nose pads appear to be molded directly into the frames. "Each nose pad has several prongs, or 'grippers' that are secured to the SDN-4 material using a proprietary process," the company says. I've observed that unlike the nose pads on the pair of Warby Parkers that I typically wear, Aspire's don't dig into my nose or leave furrows like the WP's do; when I take off the Aspires, you can't tell I was wearing them. (The nosepads on the Aspires also haven't fallen off as the left one on my Warbys occasionally does, but then I've only been testing these for a month.)
Something I noticed by switching back and forth between the Warby Parkers and the Aspires is how much lighter and more comfortable the Aspires are. It almost feels like you're not wearing glasses at all. What I mean by this, concretely, is that the stems of my Warbys exert a particular amount of pressure on my temples, yet despite that pressure will slide down my nose over time. In contrast the stems on the Aspires exert much less pressure on my temples, yet stay firmly in place, even when I'm in the shop and bending over stuff, standing on a ladder and looking straight up to adjust something on the ceiling, or looking directly down on items.
Which is to say, the Aspires have a noticeable performance advantage in that they never move on my face regardless of my head angle, yet they exert less pressure on both the temples and the sides of my nose. I couldn't figure out why this would be—it's paradoxical—but I'm pretty sure it has to do with weight. I threw both pairs on a kitchen scale to see:
The Warby Parkers
The Aspires
I'm no eyeglass expert, but it appears that the Aspire frame's lighter weight is what keeps them firmly fixed in place despite being more comfortable. And that's probably why the company is billing them as ideal for "active situations like running or boating or golfing" in addition to desk duty.
Alas, the Aspires are too wide for my face, aesthetically; my pupils are 59 millimeters on-center, and asymmetrical to boot, so I often have trouble finding glasses that fit me. But this is no fault of the company's, and if I had to recommend a pair of eyeglasses to a friend—even one that works in a shop environment, spends time in the gym or runs—with a more average pupillary distance, I'd recommend the Aspires over the Warbys, Prodesign Denmarks and Guccis I've previously owned.
Admittedly, I don't have experience with the brand that Aspire has in their sights:
"The only company that might be considered a competitor in performance right now is Lindberg," says the company. "That brand does not use a similar material, though," (I looked into it, Lindberg uses acetate)—"and is available at a much more expensive price point. Aspire is available in the affordable luxury price point of $240-$280."
I'm curious to hear from the eyeglass wearers among you, particularly those of you that work in shop environments: What brand do you wear, and what qualities do you prize? Also, do any of you have a pupillary distance of 59 millimeters, and if so, what the heck fits?

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