TR90 vs Acetate: What's the Difference, and Why We Built Folds With TR90
If you've shopped for glasses before, you've probably seen acetate mentioned everywhere. It's the material behind most designer eyewear, and for good reason, it looks fantastic. But when we set out to build Folds, we needed a material that could do something acetate was never designed to do: fold flat, travel in a pocket, and survive daily life without cracking. That's why we chose TR90.
Here's an honest look at both materials, what each one is good at, and why TR90 made sense for a folding frame.
What Is Acetate?
Acetate is a plant based plastic that has been the standard in eyewear for decades. It's prized for its glossy finish, rich colour depth, and the way it can be layered to create patterns like tortoiseshell. If you want a frame with real depth and shine, acetate is hard to beat.
The trade-off is that acetate is rigid rather than flexible. It looks and feels premium sitting still, but it's not designed to bend, fold, or take repeated stress. Push it too far and it's more likely to crack than flex back into shape. It's also a heavier material, and in very cold conditions, it can become more brittle.
What Is TR90?
TR90 is a lightweight thermoplastic originally developed for aerospace and technical applications, chosen for parts that need to survive stress without snapping. In eyewear, that translates into a frame that can flex under pressure and return to its original shape rather than cracking.
TR90 is also significantly lighter than acetate, holds up well across a wide range of temperatures, and is naturally hypoallergenic, which makes it comfortable for extended daily wear. It doesn't have quite the same glassy depth as acetate, but it's built for durability and performance first.
Why We Chose TR90 for Folds
Folding sunglasses go through a lot more stress than a standard pair. Every fold and unfold puts pressure on the hinge and the frame itself, and a rigid material like acetate simply isn't suited to that kind of repeated movement. We needed something that could fold flat, live in a bag or pocket, and still hold its shape after months of use.
TR90 was the clear choice. It's why Folds can fold down smaller than a phone at under 19 grams, without the frame becoming the weak point. Combined with genuine polarised UV400 lenses and a spring hinge for a comfortable fit, TR90 lets Folds do something acetate frames were never built to do: travel with you, every day, without compromise.
The Bottom Line
Acetate isn't a lesser material, it's simply built for a different job. If you want a rigid, glossy, traditional frame that stays in one shape, acetate does that beautifully. But if you want a frame that folds flat, survives daily wear, and goes wherever you go, TR90 is the better foundation, and it's exactly why we built Folds around it.
