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D387-00 – Standard Test Method Technical Guide
🎯 Purpose and Scope of D387-00
ASTM D387-00 is a referee test method for comparing the color and strength of chromatic pigments against a reference standard using a mechanical muller. The standard explicitly excludes white pigments, which are instead evaluated under Test Methods D332 (Visual Observation) and D2745 (Reflectance Measurements). The method utilizes a suitably chosen vehicle and white base for tints, and mandates that the test and standard pigments are treated identically throughout the process. Per Section 1.3, the values stated in SI units are the preferred unit of measurement.
⚠️ Critical Distinction: This method is strictly for chromatic pigments. Do not use it for white pigments (use D332 or D2745). For dispersion of color pigments using a miniature sandmill rather than a mechanical muller, refer to ASTM D3022.
⚙️ Mechanical Muller Dispersion Procedure
The core methodology requires dispersing both the test pigment and the reference standard in a suitable vehicle using a mechanical muller. Identical treatment is mandatory. Following dispersion, opaque drawdowns are prepared for evaluation. The standard assumes the most accurate comparison of mass color and tinting strength occurs at complete dispersion. The conditions required to achieve this maximum practical degree of dispersion are detailed in Annex A1 of the standard.
Section 5.2 provides critical flexibility: while a specific vehicle and white base are suggested for the referee method, the standard explicitly permits the use of alternative vehicles and whites for routine quality control purposes, provided such changes are agreed upon by all parties to the test.
| 📏 Standard | 🎯 Application | ⚡ Key Dispersion Equipment |
|---|---|---|
| D387-00 | Color & Strength of Chromatic Pigments | Mechanical Muller |
| D3022 | Color & Strength of Color Pigments | Miniature Sandmill |
| D332 | Relative Tinting Strength of White Pigments | Visual Observation |
| D2745 | Relative Tinting Strength of White Pigments | Reflectance Measurements |
| D4838 | Relative Tinting Strength of Chromatic Paints | General Laboratory Method |
📊 Evaluation and Significance of Results
According to Section 5.1, color and tinting strength are the most important properties of a color pigment, making this method essential for quality control and referee decisions. The opaque drawdowns can be evaluated either visually, following Practice D1729, or instrumentally, by calculating color differences per Practice D2244. Users must be aware of the important caveat in Section 5.4: results obtained with a mechanical muller do not necessarily correlate directly with industrial dispersing equipment, though the method provides a controlled and repeatable standard for comparison.
| 🔍 Property | ⚡ Evaluation Method | 📐 Governing Practice |
|---|---|---|
| Mass Color & Strength | Visual Comparison of Drawdowns | D1729 (Visual Appraisal) |
| Color Differences & Tolerances | Instrumental Measurement | D2244 (Calculation of Color Differences) |
| Degree of Dispersion | Maximum Practical Limit | Annex A1 of D387-00 |
💡 Important Caveat: Section 5.4 explicitly states that results obtained with a mechanical muller “do not necessarily correlate directly with an industrial situation where different dispersing conditions exist.” This method serves as a controlled referee standard, not a direct simulation of production dispersion.
❓ Frequently Asked Questions
🔍 Can D387-00 be used to evaluate white pigments?
No. The scope (Section 1.2) explicitly states: “This test method does not apply to white pigments.” White pigments are evaluated using Standards D332 (Visual Observation) or D2745 (Reflectance Measurements).
💡 What is the primary difference between D387 and D3022?
Both evaluate chromatic pigment color and strength. However, D387-00 specifies the use of a mechanical muller for dispersion, whereas D3022 utilizes a miniature sandmill. The choice between the two methods often depends on the standard equipment agreed upon by the testing parties.
⚡ Is the suggested vehicle in the standard mandatory to use?
No. Section 5.2 clarifies that a vehicle and white are suggested specifically for the referee method. For routine quality control purposes, alternative vehicles and whites may be used, provided this is agreed upon by the parties to the test.
📌 What unit of measurement is preferred in this standard?
Per Section 1.3, the values stated in SI units are the preferred unit of measurement. Any values provided in parentheses throughout the standard are for informational purposes only.