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D3722-05 – Standard Test Method Technical Guide
📜 Scope and Specifications
This specification covers dry and wet ground naturally occurring iron oxide, dry and wet ground calcined naturally occurring iron oxide, and mixtures of these with synthetic iron oxides. These pigments are suitable for use in paints, coatings, and many other applications. The standard was developed in accordance with internationally recognized principles on standardization established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
📊 Composition and Property Requirements
The pigments must conform to the following requirements for composition and properties:
| 🟦 Property | 📏 Requirement |
|---|---|
| Total iron as Fe₂O₃, min % | 40.0 |
| Moisture and other volatile matter, max % | 1.0 |
| Organic coloring matter | None |
| Total sulfates expressed as SO₃, max % | 2.0 |
| Matter soluble in water, max % | 2.0 |
| Matter soluble in water (primer pigments), max % | 1.0 |
| Coarse particles (total residue on No. 325 sieve), max % | 2.0 |
Additionally, the mass color, character of the tint, and tinting strength when mixed with a white pigment must be within mutually agreed upon limits of a standard acceptable to both purchaser and seller.
✅ Note: Primer pigments have a stricter limit of 1.0% for matter soluble in water, ensuring better performance in primer applications.
🔬 Test Methods and Sampling
Tests shall be conducted in accordance with the appropriate ASTM test methods. Sampling requires two random samples from different packages per lot, batch, or day’s pack. For shipments less than 10,000 lb, two samples are taken; for larger shipments, two samples per 5 tons are required. Samples may be tested separately or blended to form a composite sample.
Key test methods include:
- Total Iron Oxide, Sulfur, and Organic Coloring Matter: Test Methods D50
- Moisture and Other Volatile Matter: Test Method D280, Method A
- Matter Soluble in Water: Test Method D1208
- Coarse Particles in Dry Pigments: Test Method D185
⚠️ Important: For procedures not covered by ASTM test methods, test methods must be mutually agreed upon between the purchaser and seller.
❓ Frequently Asked Questions
🔍 What is the minimum iron oxide content required?
The pigment must contain at least 40.0% total iron as Fe₂O₃.
💡 What are the moisture limits for these pigments?
The maximum allowed moisture and other volatile matter is 1.0%.
⚡ How are samples taken for testing?
Two samples are taken at random from different packages per lot. For shipments under 10,000 lb, two samples are taken, and for larger shipments, two samples per 5 tons are collected.
📌 What test method covers coarse particles?
Coarse particles are tested using Test Method D185, which measures the total residue retained on a No. 325 (45-µm) sieve, with a maximum of 2.0%.