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D607-82 – Standard Test Method Technical Guide
📐 Composition and Grade Specifications
ASTM D607-82 (Reapproved 2019) establishes the requirements for wet ground muscovite mica pigments intended for use in protective coatings. This standard defines two specific grades based on particle fineness: Type A (Regular 325 M Grade) and the finer Type B (Fine Grade). All pigments must be manufactured using the wet grinding process to achieve the specified purity and platy morphology required for optimal barrier properties.
The following mandatory physical and chemical property limits ensure consistent performance across both grades:
| 🟦 Property Specification | 📏 Type A (Regular 325 M Grade) | 📏 Type B (Fine Grade) |
|---|---|---|
| Apparent Density, max (lb/ft³) | 12.0 (0.2 g/cm³) | 12.0 (0.2 g/cm³) |
| Moisture & Volatile Matter, max (wt%) | 0.5 | 0.5 |
| Grit, max (wt%) | 0.5 | 0.5 |
| Coarse Particles (No. 140 / 106 µm sieve), max (wt%) | 0.1 | 0.01 |
| Coarse Particles (No. 325 / 45 µm sieve), max (wt%) | 12.0 | 3.0 |
| Ignition Loss (dry basis), max (wt%) | 5.0 | 5.0 |
✅ Key Distinction: The primary technical difference between the two types is the coarse particle residue on the No. 325 (45 µm) sieve. Type B (Fine Grade) caps this at just 3.0%, making it highly suitable for smooth, high-gloss coating formulations, whereas Type A allows up to 12.0%.
⚙️ Sampling and Test Methods
Representative sampling is critical for verifying conformance. Per Section 4, two random samples must be taken from different packages within each lot or day’s production. For shipments exceeding 10,000 lb, the standard requires two samples for every 5-ton increment. These samples can be tested individually or blended into a composite at the purchaser’s discretion.
All testing must strictly adhere to the referenced ASTM methods to ensure reproducibility and compliance:
| 🎯 Property Evaluated | ⚡ Designated ASTM Method |
|---|---|
| Apparent Density | Test Methods D716 |
| Moisture & Volatile Matter | Test Methods D280 |
| Grit | Test Methods D716 |
| Coarse Particles | Test Methods D185 |
| Ignition Loss | Test Methods D1208 |
⚡ Important Consideration: While the standard designates specific ASTM methods, Section 5 permits the purchaser and seller to mutually agree upon alternative procedures for any properties not explicitly covered. Additionally, the color tolerances for the pigments are not fixed numerically but must be established mutually between the involved parties.
❓ Frequently Asked Questions
🔍 What does the “82 (Reapproved 2019)” designation actually mean?
The “82” indicates the year the standard was originally adopted or its last major revision. The “(Reapproved 2019)” confirms that the ASTM subcommittee reviewed the standard in 2019 and determined it remains technically valid without requiring any modifications or updates.
💡 What is the maximum apparent density allowed for both types of wet ground mica?
Both Type A and Type B must conform to a maximum apparent density of 12.0 lb/ft³ (0.2 g/cm³). This uniform limit ensures predictable bulking and volumetric efficiency in paint and coating formulations regardless of the mesh grade selected.
⚡ Which specific ASTM methods govern the testing of grit and ignition loss?
Grit is evaluated using the procedures outlined in Test Methods D716 (Standard Test Methods for Evaluating Mica Pigment). Ignition loss is determined in accordance with Test Methods D1208 (Standard Test Methods for Common Properties of Certain Pigments), ensuring a maximum loss of 5.0% on a dry basis.
📌 How many samples are required for a shipment weighing less than 10,000 lb?
For shipments under 10,000 lb, Section 4 mandates that a minimum of two random samples be taken from different packages in the lot. For larger shipments, the frequency increases to two samples per every 5 tons of material.