The face fabric on the lightest down jackets you can buy — Patagonia Down Sweater, Arc'teryx Cerium, Mountain Hardwear Ghost Whisperer, and most of the cottage-industry quilts and ultralight sleeping bags. A 20-denier nylon 6,6 ripstop, calendared (heat-and-pressure-flattened to close up the weave) so well that goose down can't migrate through it. Pertex is a brand owned by Mitsui Chemicals; the Quantum line is the ultralight downproof grade. The fabric is unreasonably thin, slightly translucent, with a subtle ripstop grid you can see only when held to the light. Designers reach for it whenever weight per square meter matters more than abrasion life — insulation shells, packable shells, ultralight tents and bivys.
Plain-weave ripstop nylon 6,6 yarn at 20 denier (~22 dtex), with reinforcing yarns at ~4 mm spacing in both directions forming the visible grid. Thread count typically 250×170 ends/picks per inch — the dense weave is what makes it downproof. Calendared on a hot-roller pass to close interstices below the diameter of the smallest down clusters (the downproof test is hours of mechanical cycling against a sample of high-fill goose down with zero migration). Fabric weight 25–35 g/m² (the lightest grades; Pertex Quantum Pro adds DWR and goes up to ~40 g/m²). Tear strength 8–15 N (low — this is not an abrasion fabric). Air permeability 1–5 cfm depending on calendar pass. DWR (durable water repellent) face finish standard. UV degradation faster than heavier nylons — published service life under sun is 500–800 hours. Sews readily but the fabric is slippery and tunnels under the foot, requires a walking foot or careful tension. Bartacks at every load point because seam strength dominates fabric strength at this weight.
Principled BSDF defaults derived from the sphere fibrous finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material. Or grab the whole library at once: ForMaterials library →
# finish: fibrous albedo #3a4a55 metallic 0.00 roughness 0.70 ior 1.45 transmission 0.00 clearcoat 0.00 sheen 0.70 anisotropic 0.50
{
"albedo": "#3a4a55",
"metallic": 0.0,
"roughness": 0.7,
"ior": 1.45,
"transmission": 0.0,
"clearcoat": 0.0,
"sheen": 0.7,
"anisotropic": 0.5
}
# Blender 4.x — Principled BSDF
# Pertex® Quantum (Ultralight Calendared Ripstop) · finish: fibrous
import bpy
mat = bpy.data.materials.new(name="mat_pertex_quantum")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value = (0.0423, 0.0685, 0.0908, 1.0)
bsdf.inputs["Metallic"].default_value = 0.000
bsdf.inputs["Roughness"].default_value = 0.700
bsdf.inputs["IOR"].default_value = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value = 0.000
bsdf.inputs["Sheen Weight"].default_value = 0.700
bsdf.inputs["Anisotropic"].default_value = 0.500
# KeyShot 11+ — lux Python API, Generic material
# Pertex® Quantum (Ultralight Calendared Ripstop) · finish: fibrous
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_pertex_quantum", materialType="Generic")
mat.setProperty("diffuse", (58, 74, 85)) # 8-bit sRGB
mat.setProperty("metallic", 0.000)
mat.setProperty("roughness", 0.700)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)
{
"_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
"_about": "Pertex\u00ae Quantum (Ultralight Calendared Ripstop) \u00b7 finish: fibrous",
"baseColor": {
"r": 0.0423,
"g": 0.0685,
"b": 0.0908
},
"metallic": 0.0,
"roughness": 0.7,
"ior": 1.45,
"opacity": 1.0,
"anisotropyLevel": 0.5,
"_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}{
"asset": {
"version": "2.0",
"generator": "ForMatter"
},
"materials": [
{
"name": "mat_pertex_quantum",
"pbrMetallicRoughness": {
"baseColorFactor": [
0.0423,
0.0685,
0.0908,
1.0
],
"metallicFactor": 0.0,
"roughnessFactor": 0.7
},
"extensions": {
"KHR_materials_ior": {
"ior": 1.45
},
"KHR_materials_sheen": {
"sheenColorFactor": [
1.0,
1.0,
1.0
],
"sheenRoughnessFactor": 0.7
}
}
}
]
}# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Pertex® Quantum (Ultralight Calendared Ripstop) · finish: fibrous
def Material "mat_pertex_quantum" {
token outputs:surface.connect = </mat_pertex_quantum/PreviewSurface.outputs:surface>
def Shader "PreviewSurface" {
uniform token info:id = "UsdPreviewSurface"
color3f inputs:diffuseColor = (0.0423, 0.0685, 0.0908)
float inputs:metallic = 0.000
float inputs:roughness = 0.700
float inputs:ior = 1.450
float inputs:opacity = 1.000
float inputs:clearcoat = 0.000
token outputs:surface
}
}
Pertex Mitsui technical literature; outdoor-industry shell-fabric technical bulletins.
House vocabulary — terms ForMatter uses with intent.
Materials and processes for people who design and make things.
A local-first library of materials, processes, applications, and finishes — equal weight, citable everywhere, so a student can move from "what is this" toward "what's actually buildable here, now, by me." Part of the renato.design ecosystem — sibling of Plenum, Specimen, Ingenue, gesture, graf, and the Renato Rhino plug-ins. Form and matter, inseparable.
Half of teaching materials is teaching how the material is made into the thing. The standard subscription library was always light on that half. The wedge here isn't better samples or a prettier interface — it's treating Process as a peer entity, not a footnote.
Conway, Lefteri, Forty, Sparke, ASM, GIA. Every voice: Voices.
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