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D1960-86 – Standard Test Method Technical Guide
🔬 Scope and Significance
ASTM D1960-86 defines a standard procedure for determining the mass of moisture and other volatile materials present in natural drying oils. This test method is essential for qualifying incoming raw materials, as residual solvents or volatile adulterants can significantly impact the performance of oil-based coatings and resins.
A critical aspect of this method is the use of an inert gas blanket over the specimen. As noted in Section 3, heating drying oils in air can cause oxidation and a corresponding weight gain, which would mask the true volatile loss. The inert gas minimizes this interference.
💡 Tip for Solvent-Containing Samples: For drying oils dissolved in volatile organic solvents, the standard specifically recommends using Test Methods D 1259 or D 1644 instead of this procedure.
| 🟦 Apparatus / Parameter | 📏 Specification |
|---|---|
| Air Oven | Maintained at 105 ± 2°C |
| Desiccator | Must contain an efficient desiccant |
| Inert Gas | Carbon Dioxide or Nitrogen (Warning: high pressure) |
| Specimen Mass | 10 g, weighed to 0.1 mg |
| Test Vessel | Tared 50-mL flask |
| Heating Duration | 30 minutes |
⚙️ Test Procedure and Calculation
The procedure requires weighing a 10 g specimen into a tared 50-mL flask. The flask is then placed in an air oven at 105 ± 2°C for exactly 30 minutes. Throughout this heating period, a gentle stream of carbon dioxide or nitrogen must be directed into the neck of the flask to blanket the oil surface.
The percent loss on heating (L) is calculated using the following formula:
L = [(S - R) / S] × 100
Where:
S = specimen weight before heating (g)
R = specimen weight after heating and cooling (g)
⚠️ Critical Procedure Note: Section 6.2 clarifies that the flask must be cooled in a desiccator before reweighing to prevent moisture adsorption and ensure accurate mass readings. Section 5 provides a strong warning regarding the high pressure of CO2 and N2 cylinders.
📊 Precision and Status
According to Section 8 of the standard, the precision and bias of this test method have not been formally determined. Despite this, the standard notes that “this method has been in use for many years, and its usefulness has been well established.” It remains a widely accepted benchmark in the industry for quality control of drying oils.
❓ Frequently Asked Questions
🔍 Why is an inert gas blanket required during the test?
Heating drying oils in air promotes oxidation, which causes a weight gain. This weight gain counteracts the weight loss from volatiles escaping, leading to falsely low “loss on heating” values. The inert gas (CO₂ or N₂) prevents this oxidation (See Significance and Use, Section 3).
💡 What are the exact test conditions for temperature and time?
The specimen must be heated for 30 minutes at 105 ± 2°C (See Procedure, Section 6.1). Strict adherence to this schedule is required for reproducible results.
⚠️ What safety precautions are specified for the gas cylinders?
The standard provides an explicit hazard warning (Section 5) that carbon dioxide and nitrogen in cylinders are dangerous due to their extremely high pressure. It requires users to prevent damage to cylinders, valves, and pressure regulators, and to consult the supplier’s Material Safety Data Sheet.
📌 Is this test suitable for oils dissolved in solvents?
No. The Scope (Section 1.1) clearly states the method is for natural drying oils. For solutions in volatile organic solvents, the standard directs users to Test Methods D 1259 or D 1644 (See Note 1).