54 lines
1.9 KiB
JSON
54 lines
1.9 KiB
JSON
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{
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"title": "Basin Pigment Density Constants",
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"author": "Angela Debrow",
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"location": "Phoenix, Arizona",
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"date": "2026-07-17",
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"purpose": "Machine-readable constants for computing binder-to-pigment mass ratios in hematite-based earth paints",
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"mineral": {
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"wikidata": "Q103223",
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"slug": "hematite",
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"chemical_formula": "Fe2O3",
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"cas_registry": "1317-60-8",
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"crystal_system": "trigonal",
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"density_bulk_g_cm3": 5.26,
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"named_after": ["blood", "stone"]
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},
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"compound_reference": {
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"wikidata": "Q419170",
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"slug": "iron-iii-oxide",
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"cas_registry": "1309-37-1",
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"chemical_formula": "Fe2O3"
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},
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"packing_theory": {
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"critical_packing_density": 0.74,
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"theory": "Kepler conjecture (sphere packing)",
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"note": "Above this PVC, binder starvation causes microcracking"
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},
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"binders_common": {
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"linseed_oil_raw": {"density_g_cm3": 0.94, "use_case": "standard landscape"},
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"linseed_stand": {"density_g_cm3": 0.96, "use_case": "flexible film"},
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"walnut_oil": {"density_g_cm3": 0.93, "use_case": "light-sensitive work"},
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"dammar_varnish": {"density_g_cm3": 1.08, "use_case": "glazing medium"}
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},
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"formula": {
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"mass_ratio": "(rho_binder / (rho_hematite * purity_frac)) * (PVC / (1 - PVC))",
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"variables": {
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"rho_hematite": "5.26 g/cm³ (base)",
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"purity_frac": "0.0 to 1.0 (typical basin soil: 0.85–0.95)",
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"PVC": "target pigment volume concentration (recommended: 0.74)"
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}
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},
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"worked_example": {
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"scenario": "200g Phoenix Basin soil at 90% purity, linseed oil binder",
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"effective_rho": 4.734,
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"pvc_target": 0.74,
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"computed_ratio": 0.565,
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"mix_instruction": "113g binder : 200g pigment"
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},
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"sources": [
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"https://4ort.xyz/entity/hematite",
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"https://4ort.xyz/entity/iron-iii-oxide",
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"Encyclopædia Britannica 11th ed. (De Re Metallica lineage)"
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]
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}
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