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D1954-86 – Standard Test Method Technical Guide
Test Method D 1954 – 86 (Reapproved 1995) defines a standard empirical volumetric procedure for determining foots (solid impurities) in raw linseed oil. This method utilizes specific reagents—including an acid-calcium chloride solution and acetone—to stratify suspended impurities in a graduated tube, where the volume of the foots layer is directly measured. The test is performed at two distinct temperature conditions, yielding Heated and Chilled Foots results.
🧪 Apparatus and Reagent Specifications
Strict adherence to the specified apparatus and reagent purity is critical to the reproducibility of the volumetric foots determination. Sections 6 and 7 of the standard outline the precise dimensional and chemical quality requirements.
| 🟦 Component | 📏 Specification |
|---|---|
| Graduated Tube | 70 mL min capacity, 10–15 mm ID, 0.1 mL graduations from 10–50 mL |
| Thermometer | ASTM 1C, Partial Immersion, −20 to +150°C |
| Water Bath | Maintained at 25 ± 0.5°C |
| Sample Bottles | 60 mL (2-oz) |
| Reagent Water | Per Specification D 1193 |
⚠️ Critical Dimensional Tolerance: The graduated tube specified in Section 6.5 must strictly conform to a 10–15 mm internal diameter with 0.1 mL graduations extending from 10 mL to 50 mL. Standard glassware substitutions that do not meet these specific requirements will invalidate the volumetric measurement.
⚙️ Test Procedure for Heated and Chilled Foots
The procedure mandates a two-temperature analysis derived from a single prepared sample. As described in Section 5.2, the oil is initially heated to 65°C and then divided. One portion is cooled to 25°C for the Heated Foots determination, while the other is cooled to approximately 0°C for the Chilled Foots determination before the reagents are added.
| 🔍 Parameter | 🔥 Heated Foots | ❄️ Chilled Foots |
|---|---|---|
| Initial Oil Temp | 65°C | 65°C |
| Sample Temp Before Test | 25 ± 0.5°C | ~0°C |
| Reagent Mix | Acid-CaCl₂ + Acetone | Acid-CaCl₂ + Acetone |
| Settling Vessel | Graduated Tube | Graduated Tube |
| Result | Volume of Foots (mL) | Volume of Foots (mL) |
💡 Procedural Insight: The standard emphasizes strict timing and consistent mixing conditions, as the volume of the impurity stratum increases over time due to hydration (Section 5.1). Note 1 of the standard also states that Test Method D 1966 (Gravimetric Method) is a more reproducible alternative and can be used upon mutual agreement between the purchaser and seller.
📊 Key Measured Properties and Significance
The sole direct measurement is the volume of the stratified solid layer (foots) in the graduated tube. This volume quantifies the material insoluble in a mixture of equal parts acetone and the oil under test, and insoluble in calcium chloride solution under the specific conditions of the test (Section 3.2.1).
The significance of the test (Section