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D4462-02 – Standard Test Method Technical Guide
🧪 Chemical Composition and Properties
This specification covers zinc hydroxy phosphite pigment with the general formula ZnHPO₃·[ZnO·2Zn(OH)₂]. The pigment shall conform to the composition requirements detailed in Table 1 of the standard. The mass color of the dry pigment is white. When specified, the shade and tinting strength shall be within mutually agreed limits of a reference sample acceptable to both purchaser and seller, as tested by an agreed procedure.
Technical Note: The formula ZnHPO₃·[ZnO·2Zn(OH)₂] indicates a complex zinc hydroxy phosphite structure. For complete chemical analysis, refer to Test Method D4450.
📊 Test Methods and Requirements
Testing shall be conducted in accordance with the following ASTM test methods:
- Chemical Analysis – Test Method D4450
- Moisture Loss – Method A of Test Methods D280
- Oil Absorption – Test Method D281
- Sieve Residue – No. 325 sieve using Test Methods D185 for insoluble dry pigments
| 📐 Test Method | 🎯 Property Measured | ⚡ Referenced Section |
|---|---|---|
| D4450 | Chemical composition | 5.2 |
| D280 (Method A) | Hygroscopic moisture loss | 5.3 |
| D281 | Oil absorption | 5.4 |
| D185 | Coarse particles (No. 325 sieve) | 5.5 |
Sampling Caution: Follow Section 4 carefully. Two random samples must be taken from different packages per lot or batch. For shipments over 10,000 lb, increase samples accordingly. Composite sampling is at purchaser’s discretion.
⚙️ Sampling and Keywords
Sampling is critical for quality assurance. As per Section 4, two samples are taken from different packages in each production unit. The following table summarizes the sample requirements based on shipment weight:
| 📏 Shipment Weight | 📐 Number of Samples |
|---|---|
| Less than 10,000 lb (4,545 kg) | 2 samples |
| 10,000 lb or more | 2 samples per 10,000 lb increment |
At the option of the purchaser, samples may be tested separately or blended to form a composite sample. Keywords associated with this standard include: phosphorous acid, pigment, zinc, zinc hydroxy phosphite, zinc oxide. This pigment is used in paints and related coatings.
❓ Frequently Asked Questions
🔍 What does the formula ZnHPO₃·[ZnO·2Zn(OH)₂] represent?
It represents the chemical structure of zinc hydroxy phosphite pigment, a complex compound with zinc, hydrogen, phosphite, and hydroxide components.
💡 Which ASTM test methods are required for evaluation?
© 2026 TNLab — This article is a technical interpretation for reference only. The original standard as published by ASTM International takes precedence.