The clear, glassy plastic of every SLA, DLP, or MSLA 3D-printed part. A photopolymer is a liquid resin that hardens when hit with UV light at ~405 nm. The print machine — desktop Formlabs Form 4, Anycubic Photon, or industrial Carbon DLS — paints the next layer's cross-section with UV, the resin solidifies in place, the build platform lifts a layer, the next slice paints, and the part grows hanging upside-down out of the vat. Pulled out of the printer the part is sticky and not yet at full strength — you wash it in isopropanol to clear off uncured resin and then post-cure it in a UV chamber for ten to thirty minutes to reach final strength. The plastic underneath the wash is harder and more brittle than the FDM plastics next to it on the shelf — much higher detail (you can resolve features below 0.1 mm), much smoother surface (no layer striations like FDM), but more brittle (think glass-filled epoxy, not nylon). Standard for jewelry-casting masters, dental aligners, miniatures, design-review prototypes where the surface finish has to read close to injection-molded. Not durable in sunlight — left on a windowsill for months, untreated cured resin yellows and embrittles further.
Cross-linked thermoset network of acrylate and methacrylate monomers and oligomers, polymerized by free-radical chain reaction initiated by a photoinitiator (typically a phosphine oxide such as TPO or a benzoyl-derived compound) absorbing 365–405 nm UV light. The cross-linked network does not flow on reheat (distinct from thermoplastics) and cannot be remelted or recycled into feedstock. Density 1100–1200 kg/m³ post-cure. Tensile strength 38–65 MPa post-cure (depends heavily on cure dose and formulation; under-cured prints often well under spec). Elongation at break 6–12 percent (compare PA12-SLS at 18–30 percent — the SLA print is brittle by comparison). Heat-deflection temperature 60–90 °C for standard formulations, 200–230 °C for high-temperature engineering formulations (Formlabs High Temp, Carbon EPX). Refractive index 1.50–1.55 — close to PMMA, hence the glass-like clarity in optical-quality formulations after polishing. Layer height typically 25–100 µm for desktop machines, 10 µm for high-resolution industrial. Standard print orientation hangs the part upside-down off the build platform; supports are part of the print and are scissored off after wash. Castable formulations (Formlabs Castable Wax, BlueCast) burn out cleanly in an investment-casting flask, leaving zero ash — the SLA-print-then-cast workflow that anchors modern jewelry production.
Principled BSDF defaults derived from the sphere transparent finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material. Or grab the whole library at once: ForMaterials library →
# finish: transparent albedo #e8eef0 metallic 0.00 roughness 0.05 ior 1.50 transmission 1.00 clearcoat 0.00 sheen 0.00 anisotropic 0.00 thickness 1.00 attenuation_distance 0.60
{
"albedo": "#e8eef0",
"metallic": 0.0,
"roughness": 0.05,
"ior": 1.5,
"transmission": 1.0,
"clearcoat": 0.0,
"sheen": 0.0,
"anisotropic": 0.0,
"thickness": 1.0,
"attenuation_distance": 0.6
}
# Blender 4.x — Principled BSDF
# Clear Photopolymer Resin (UV-cure SLA / DLP / MSLA) · finish: transparent
import bpy
mat = bpy.data.materials.new(name="mat_resin_photopolymer_clear")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value = (0.807, 0.855, 0.8714, 1.0)
bsdf.inputs["Metallic"].default_value = 0.000
bsdf.inputs["Roughness"].default_value = 0.050
bsdf.inputs["IOR"].default_value = 1.500
bsdf.inputs["Transmission Weight"].default_value = 1.000
bsdf.inputs["Coat Weight"].default_value = 0.000
bsdf.inputs["Sheen Weight"].default_value = 0.000
bsdf.inputs["Anisotropic"].default_value = 0.000
# KeyShot 11+ — lux Python API, Generic material
# Clear Photopolymer Resin (UV-cure SLA / DLP / MSLA) · finish: transparent
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_resin_photopolymer_clear", materialType="Generic")
mat.setProperty("diffuse", (232, 238, 240)) # 8-bit sRGB
mat.setProperty("metallic", 0.000)
mat.setProperty("roughness", 0.050)
mat.setProperty("indexOfRefraction", 1.500)
mat.setProperty("transparency", 1.000)
mat.setProperty("coatingWeight", 0.000)
{
"_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
"_about": "Clear Photopolymer Resin (UV-cure SLA / DLP / MSLA) \u00b7 finish: transparent",
"baseColor": {
"r": 0.807,
"g": 0.855,
"b": 0.8714
},
"metallic": 0.0,
"roughness": 0.05,
"ior": 1.5,
"opacity": 0.0,
"anisotropyLevel": 0.0,
"_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_resin_photopolymer_clear",
"pbrMetallicRoughness": {
"baseColorFactor": [
0.807,
0.855,
0.8714,
1.0
],
"metallicFactor": 0.0,
"roughnessFactor": 0.05
},
"extensions": {
"KHR_materials_transmission": {
"transmissionFactor": 1.0
}
}
}
]
}# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Clear Photopolymer Resin (UV-cure SLA / DLP / MSLA) · finish: transparent
def Material "mat_resin_photopolymer_clear" {
token outputs:surface.connect = </mat_resin_photopolymer_clear/PreviewSurface.outputs:surface>
def Shader "PreviewSurface" {
uniform token info:id = "UsdPreviewSurface"
color3f inputs:diffuseColor = (0.807, 0.855, 0.8714)
float inputs:metallic = 0.000
float inputs:roughness = 0.050
float inputs:ior = 1.500
float inputs:opacity = 0.000
float inputs:clearcoat = 0.000
token outputs:surface
}
}
Formlabs / 3D Systems photopolymer datasheets; ASTM ISO/ASTM 52900.
Stereolithography epoxy with rapid-prototyped cast and 24k gold; an early studio application of SLA photopolymer to jewelry. Accession 2001.24.
Hexagonal honeycomb-like structure representing the cell shape of diabetes mellitus, designed in CAD from glucose-monitor digital data. The pallid coloring intentionally suggests death — bio-data driving the form, photopolymer driving the build.
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, with cost-over-volume curves, trade-off profiles, equipment-tier filters, and second-life paths layered onto the data 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's Material World on raw materials, Lefteri's Making It on processes, Forty's Concrete and Culture, Sparke's Design in Context, Bürdek's Design: History, Theory and Practice of Product Design, Schröpfer's Material Design on materials in architecture, Winchester's The Perfectionists on tolerance, Minshall's Your Life Is Manufactured on the global supply chain, von Busch's Making Trouble on material activism, Were's How Materials Matter, Hegger / Drexler / Zeumer's Basics Materials, Untracht and McCreight on metalsmithing, USDA Forest Products Lab on woods, GIA on gemstones, Schott / CoorsTek / Toray / Owens Corning datasheets, MakeItFrom for verifiable property numbers, ASM Handbook, ISO standards. Museum holdings draw from the Met, MAD, V&A, Smithsonian American Art Museum, Newark Museum of Art, British Museum, Heard Museum, Smithsonian NMAI, Eiteljorg Museum, Philadelphia Museum of Art, Cranbrook Art Museum, and Grand Rapids Art Museum — collection-record permalinks only, designer overview pages and exhibition listings excluded. Voice blocks now ride on every entry kind — material, process, application, and finish — and include Ruskin on iron, Anni Albers on twining, Greg Lynn on the shred-and-teeth NURBS lineage, Pugin on the metal that won't be hammered, Barthes / Yanagi / Benjamin channeled within their philosophy; Sparke, Bürdek, Forty, Conway, Schröpfer, Minshall, von Busch, Lefteri, Pat Pruitt, Mary Lee Hu, Tom Joyce, Albert Paley, and the rest of the contemporary makers quoted verbatim with citation. All cited.
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