The transparent water-thinned paint of every watercolor painting, every fashion illustration, every botanical illustration since the early 1800s when the modern formulation matured. Watercolor is the simplest paint chemistry — dry pigment ground with a water-soluble binder (gum arabic, the canonical binder; honey or glycerin as humectants; ox gall as wetting agent) — packaged in a tube (wet, ready-to-use) or in a pan (dry block, activated with brush + water). The defining property is transparency — the paint film is thin enough to let the white of the paper show through, so light passes through the pigment to the paper and back, producing the luminous quality watercolor is known for. Winsor & Newton (UK, since 1832) is the heritage canon; Daniel Smith (US, since 1976) leads the modern color-innovation tier with their PrimaTek mineral pigments; Holbein (Japan) leads the fashion-illustration tier. Buy from Dick Blick / Daniel Smith / specialty art-supply houses.
Water-soluble pigmented coating, simplest formulation: pigment (lightfast inorganic or synthetic organic, ground to 1-5 µm particle size for transparency) + gum arabic binder (10-30 percent by weight) + glycerin / honey humectant (5-10 percent) + water + minor preservatives + ox gall surfactant (in some formulations, replaced by synthetic alternatives). Tube format: paint is packaged at toothpaste consistency in metal tubes (5-15 ml typical), squeezed onto palette, activated with water. Pan format: paint is air-dried into half-pan or full-pan blocks (1-3 g pigment per pan), activated by wetting the surface with brush + water — the canonical pochade-box / plein-air format. Pigment lightfastness graded by manufacturer per Blue Wool Scale (BWS) or ASTM D5067 — Series I-V (W&N) or comparable manufacturer scales — designating colors for permanent / archival vs. fugitive (some historical pigments like rose madder are fugitive and should be avoided for permanent work). Transparency (T) / semi-transparent (ST) / semi-opaque (SO) / opaque (O) ratings on each paint indicate the optical character. Pigment Color Index (CI) numbers (PB28 = cobalt blue, PR108 = cadmium red, etc.) are the international identification of the actual pigment chemistry used — informed buyers spec by CI number rather than manufacturer color name. Lifts (re-wets, can be partly removed with damp brush) — the working property that distinguishes watercolor from acrylic. Cleans up with water; brushes survive indefinitely with care.
Principled BSDF defaults derived from the sphere glossy finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material. Or grab the whole library at once: ForMaterials library →
# finish: glossy albedo #3a6090 metallic 0.00 roughness 0.25 ior 1.45 transmission 0.00 clearcoat 0.40 sheen 0.00 anisotropic 0.00
{
"albedo": "#3a6090",
"metallic": 0.0,
"roughness": 0.25,
"ior": 1.45,
"transmission": 0.0,
"clearcoat": 0.4,
"sheen": 0.0,
"anisotropic": 0.0
}
# Blender 4.x — Principled BSDF
# Watercolor (Tube / Pan, Winsor & Newton Professional) · finish: glossy
import bpy
mat = bpy.data.materials.new(name="mat_watercolor_winsor_newton")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value = (0.0423, 0.117, 0.2789, 1.0)
bsdf.inputs["Metallic"].default_value = 0.000
bsdf.inputs["Roughness"].default_value = 0.250
bsdf.inputs["IOR"].default_value = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value = 0.400
bsdf.inputs["Sheen Weight"].default_value = 0.000
bsdf.inputs["Anisotropic"].default_value = 0.000
# KeyShot 11+ — lux Python API, Generic material
# Watercolor (Tube / Pan, Winsor & Newton Professional) · finish: glossy
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_watercolor_winsor_newton", materialType="Generic")
mat.setProperty("diffuse", (58, 96, 144)) # 8-bit sRGB
mat.setProperty("metallic", 0.000)
mat.setProperty("roughness", 0.250)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.400)
{
"_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
"_about": "Watercolor (Tube / Pan, Winsor & Newton Professional) \u00b7 finish: glossy",
"baseColor": {
"r": 0.0423,
"g": 0.117,
"b": 0.2789
},
"metallic": 0.0,
"roughness": 0.25,
"ior": 1.45,
"opacity": 1.0,
"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_watercolor_winsor_newton",
"pbrMetallicRoughness": {
"baseColorFactor": [
0.0423,
0.117,
0.2789,
1.0
],
"metallicFactor": 0.0,
"roughnessFactor": 0.25
},
"extensions": {
"KHR_materials_ior": {
"ior": 1.45
},
"KHR_materials_clearcoat": {
"clearcoatFactor": 0.4
}
}
}
]
}# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Watercolor (Tube / Pan, Winsor & Newton Professional) · finish: glossy
def Material "mat_watercolor_winsor_newton" {
token outputs:surface.connect = </mat_watercolor_winsor_newton/PreviewSurface.outputs:surface>
def Shader "PreviewSurface" {
uniform token info:id = "UsdPreviewSurface"
color3f inputs:diffuseColor = (0.0423, 0.117, 0.2789)
float inputs:metallic = 0.000
float inputs:roughness = 0.250
float inputs:ior = 1.450
float inputs:opacity = 1.000
float inputs:clearcoat = 0.400
token outputs:surface
}
}
Winsor & Newton watercolor lightfastness ratings; AIC watercolor-conservation literature.
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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