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D5067-16 – Standard Test Method Technical Guide
ASTM D5067-16 (Reapproved 2021) establishes comprehensive quality standards for the composition, physical properties, performance, and labeling of artists’ watercolor paints. Developed by Subcommittee D01.57 on Artist Paints and Related Materials, this specification serves as a crucial benchmark for producers, distributors, and artists, ensuring a common language regarding pigment identification, permanence, and lightfastness.
🎨 Scope and Purpose of the Standard
The specification outlines strict requirements for pigments, vehicles, and additives used in watercolor paints. A key focus is placed on pigment identification, lightfastness, and consistency (Section 1.2). While the standard sets a baseline for professional-grade quality, it acknowledges in Section 4.2 that variations in manufacture not covered by the specification may lead to artist preference differences between brands.
The material itself is specifically defined as a “pigment dispersion in a water soluble gum/resin vehicle that dries water soluble and is intended primarily for transparent applications” (Section 3.2.1). All values are stated in SI units as the primary standard.
🧪 Pigment Identification and Lightfastness Requirements
Central to the standard is the mandatory labeling system. According to Section 5.1.1, every label must clearly state the Common Name, Colour Index Name (e.g., PB 15, PY 151), and the Lightfastness Category for every pigment contained in the paint. The Colour Index Number (e.g., 74160) serves as the chemical constitution identifier. Lightfastness is rigorously evaluated using Test Methods D4303, and Table 1 of the standard provides a non-exhaustive list of pigments that meet these lightfastness criteria.
| 🟦 Pigment Common Name | 📛 Colour Index Name | 🎯 Colour Index Number | ☀️ Lightfastness Category |
|---|---|---|---|
| Phthalocyanine Blue | PB 15 | 74160 | ASTM I (Excellent) |
| Quinacridone Magenta | PR 122 | 73915 | ASTM I (Excellent) |
| Azo Yellow | PY 151 | 13980 | ASTM I (Excellent) |
| Dioxazine Purple | PV 23 | 51319 | ASTM I (Excellent) |
| Raw Sienna | PBr 7 | 77491 | ASTM I (Excellent) |
⚠️ Critical Lightfastness Warning: Many traditional “hues” (e.g., “Alizarin Crimson Hue”) or organic pigments like PR 83 (Alizarin Crimson) fail to meet the ASTM I or II lightfastness requirements under D4303. Per the spirit of D5067, a paint must identify the actual Colour Index Name of the pigment used, not just a historical marketing name.
⚙️ Test Methods and Physical Properties
The standard ensures physical excellence through referenced ASTM test methods. Test Methods D185 dictates standards for coarse particles, ensuring a smooth, consistent paint. Test Method D1210 describes the use of a Hegman-type gage for measuring the fineness of dispersion of the pigment-vehicle system. Additionally, Practice D4236 is strictly referenced, requiring all paints conforming to this specification to be labeled for chronic health hazards.
| ⚡ Test Parameter | 📏 Referenced Method | 🎯 Specification Intent |
|---|---|---|
| Coarse Particles & Grit | Test Methods D185 | Ensure a smooth, buttery texture without grittiness. |
| Fineness of Dispersion | Test Method D1210 (Hegman Gage) | Verify uniform pigment particle dispersion in the gum vehicle. |
| Lightfastness Rating | Test Methods D4303 | Determine the relative lightfastness category (ASTM I, II, or III) to predict permanence. |
| Health Hazard Labeling | Practice D4236 | Ensure artists are warned about any chronic health risks of pigments. |
✅ Compliance Verification: When purchasing professional watercolor paints, check the label for the ASTM D5067 designation alongside the D4236 conformance seal. The packaging should clearly list the Colour Index Name and Lightfastness Category for each pigment, as mandated by Section 5.1.1.
❓ Frequently Asked Questions
🔍 What does the ASTM D5067 specification primarily cover?
The specification covers the composition, physical properties, performance, and labeling of artists’ watercolor paints. This includes specific requirements for pigment identification, lightfastness categories, consistency, and health hazard labeling (Section 1.1).
💡 What exactly must be printed on the label regarding pigments?
Per Section 5.1.1, the label must provide (1) the Common Name, Colour Index Name (e.g., PB 15, PY 150), and any additional terms necessary to identify the form of the pigment, and (2) the appropriate Lightfastness Category (e.g., ASTM