{
  "title": "Watercolor Formulation Calculator Constants",
  "author": "George Levert",
  "date": "2026-07-17",
  "version": "1.0.0",
  "schema": {
    "formula": "BinderMass = PigmentMass × (OpacityIndex ÷ SpecificGravity)",
    "variables": {
      "PigmentMass": {
        "unit": "grams",
        "default": 1.0,
        "description": "Reference mass of pigment"
      },
      "OpacityIndex": {
        "unit": "dimensionless",
        "min": 0.1,
        "max": 1.0,
        "description": "Transparency target (0.1=fully transparent, 1.0=fully opaque)"
      },
      "SpecificGravity": {
        "unit": "dimensionless",
        "min": 1.0,
        "max": 15.0,
        "description": "Density of pigment relative to water"
      },
      "BinderMass": {
        "unit": "grams",
        "description": "Calculated mass of gum arabic required"
      }
    },
    "derivedConstants": {
      "filmThicknessFactor": 2.34,
      "mullingTimeCoefficient": 193,
      "gumArabicConcentration": 0.10
    }
  },
  "sources": {
    "pigmentDefinition": {
      "wikidata": "Q161179",
      "slug": "pigment",
      "description": "material that changes the color of reflected or transmitted light"
    },
    "binderMaterial": {
      "wikidata": "Q535814",
      "slug": "gum-arabic",
      "cas": "9000-01-5",
      "description": "natural gum obtained from Acacia sensu lato tree sap"
    }
  },
  "workedExample": {
    "pigment": "Ultramarine Blue",
    "specificGravity": 2.7,
    "opacityIndex": 0.25,
    "expectedBinderMass": 0.0926,
    "mullingTimeMinutes": 18
  },
  "license": "CC0-1.0"
}