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D4487-90 – Standard Test Method Technical Guide
📋 Test Methods for Calcium Borosilicate Analysis
ASTM D4487 – 90 (Reapproved 2020) provides a comprehensive set of standard test methods for the chemical and physical analysis of the pigment commercially known as calcium borosilicate. This pigment is used extensively in the paint and coatings industry, making its compositional analysis critical for quality control by both producers and users. The standard outlines procedures for determining several key components and physical properties.
| 🧪 Component / Property | 📑 Assigned Sections |
|---|---|
| Silicon Dioxide (SiO₂) | 6 – 9 |
| Iron Oxide (Fe₂O₃) | 10 – 13 |
| Boron Trioxide (B₂O₃) | 17 – 20 |
| Calcium Oxide (CaO) | 21 – 23 |
| Moisture and Volatile Matter | 24 |
| Water of Hydration | 25 – 26 |
| Coarse Particles | 27 |
| Oil Absorption | 28 |
💡 Critical Sequencing Note: Individual specimens may be used for the direct determination of SiO₂, B₂O₃, and CaO. However, SiO₂ and Fe₂O₃ must be removed from the sample matrix prior to the determination of B₂O₃ and CaO to prevent analytical interference (Section 1.3).
⚙️ Reagents, Standards, and Sample Preparation
Maintaining strict reagent purity is paramount for the accuracy of the analysis. The standard mandates the use of reagent grade chemicals conforming to the specifications of the Committee on Analytical Reagents of the American Chemical Society. Water used in all tests must be Type II reagent water as specified in ASTM D1193 (Section 4.2). When concentrated reagents are specified, exact specific gravities must be maintained:
| 🧪 Reagent | 🔬 Formula | 📏 Specific Gravity |
|---|---|---|
| Hydrochloric acid | HCl | 1.19 |
| Nitric acid | HNO₃ | 1.42 |
| Sulfuric acid | H₂SO₄ | 1.84 |
| Ammonium hydroxide | NH₄OH | 0.90 |
The standard integrates several well-established ASTM methods for specific physical tests. Coarse particles are determined using Test Methods D185, moisture and volatile matter follow D280, and oil absorption is conducted via the Spatula Rub-out method in D281. For sample preparation (Section 5), the sample must be thoroughly mixed and comminuted before any portions are taken for analysis to ensure a representative specimen.
⚠️ Safety and Regulatory Compliance: This standard does not purport to address all safety concerns associated with its use. It is the responsibility of the user to establish appropriate safety, health, and environmental practices and to determine the applicability of regulatory limitations prior to use (Section 1.5).
✅ Units of Measure: The values stated in SI units are to be regarded as the standard for all measurements within this test method. No other units of measurement are included (Section 1.4).
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D4487?
This standard covers the chemical analysis of the pigment known commercially as calcium borosilicate. It compiles recommended procedures for determining the major components and physical properties important to the paint industry.
💡 What specific components must be determined sequentially?
Silicon Dioxide (SiO₂) and Iron Oxide (Fe₂O₃) are determined first, as they must be quantitatively removed from the solution before the determination of Boron Trioxide (B₂O₃) and Calcium Oxide (CaO) can be accurately performed.
⚡ What type of water and reagents are required for this analysis?
All references to water must be understood to mean reagent water conforming to Type II of ASTM Specification D1193. All chemicals used must be reagent grade, conforming to ACS specifications.
📌 Which ASTM standards are referenced for the physical test methods?
The standard directly references ASTM D185 for Coarse Particles in Pigments, ASTM D280 for Hygroscopic Moisture, and ASTM D281 for Oil Absorption of Pigments by Spatula Rub-out.