Curve
A material library for soft-touch silicones. Eighteen formulations, characterised across hardness, surface finish, and what people actually call them when they touch them.
Course project — Materials Science
2025
- Shore-A durometer
- Surface profilometry
- Body-safe silicones
- Blind-touch user study
Case study
The problem with "feel"
Engineers measure silicone in numbers. Shore-A hardness. Tear strength. Coefficient of friction. None of these numbers tell you whether the material feels good.
Curve started as a frustration. I'd spec'd a Shore-A 30 silicone for a prototype and the result felt cheap — exactly the opposite of what the spec sheet promised. I wanted to understand the gap between what the durometer says and what the hand says.
Method
I produced 18 sample tiles, varying:
- Shore-A hardness (12, 20, 30, 45)
- Surface finish (mirror, matte cast, micro-textured at three depths)
- Outer-skin formulation (4 variants of platinum-cure silicone)
Each tile was characterised on the bench (durometer, profilometry, friction sled) and then run through a blind-touch user study with 24 participants. Participants rated each tile on a 7-point scale across nine descriptors I'd pulled from the marketing copy of every personal-product brand I could find: velvety, soft, premium, cheap, sticky, warm, dead, alive, like skin.
What came out
A correlation map showing which physical parameters drive which subjective descriptors — and importantly, where the correlation breaks. Premium correlates strongly with surface finish but only weakly with hardness. Like skin correlates with both, but only within a narrow hardness window (Shore-A 18–24).
"Soft" is not a property. It is a vocabulary problem the materials world refuses to take seriously.
This library is now my reference whenever I'm specifying outer-skin silicones for product work, and the framework — measure the bench number, then measure what people call it — is something I'd carry into any material I work with.