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D1107-21 – Standard Test Method Technical Guide
The ASTM D1107-21 standard specifies a test method for determining the ethanol-toluene solubility of wood. This test measures the content of waxes, fats, resins, oils, tannins, and other soluble components that are not part of the wood’s polymeric structure.
📐 Specimen Preparation and Apparatus
The test specimen consists of 2 g of air-dried sawdust or milled wood, ground to pass a 425 μm (40 mesh) sieve and retained on a 250 μm (60 mesh) sieve. The apparatus includes Alundum or fritted-glass filtering crucibles of coarse porosity and a Soxhlet extraction system with ground-glass joints.
| 🔧 Component | 📏 Specification |
|---|---|
| Soxhlet Extraction Flask | 250 mL capacity |
| Soxhlet Extraction Tube | 45–50 mm inner diameter, ~100 mL capacity to siphon top, siphon tube height ~55 mm |
| Condenser | Hopkins inner-cooled type |
| Filtering Crucibles | Alundum or fritted-glass, coarse porosity |
💡 Tip: The extraction tube dimensions are designed for rapid siphoning, ensuring efficient extraction with 4–6 siphonings per hour.
⚙️ Test Procedure and Extraction
Weigh two 2-g test specimens in tared crucibles. Dry one specimen at 100–105°C for 2 h, then continue drying in 1-h periods until constant weight to determine the moisture-free proportion. Place the other specimen in the Soxhlet apparatus with a small screen disk to prevent loss. Extract with 150 mL of ethanol-toluene solution for 6–8 h, maintaining brisk boiling to achieve 4–6 siphonings per hour. After extraction, evaporate the solvent, dry the flask at 100–105°C for 1 h, cool in a desiccator, and weigh until constant.
| ⚙️ Step | 📐 Parameter | 🎯 Value |
|---|---|---|
| Specimen Weight | Mass | 2 g |
| Drying Temperature | Oven | 100–105°C |
| Initial Drying Time | Duration | 2 h |
| Extraction Solvent Volume | Amount | 150 mL |
| Extraction Duration | Time | 6–8 h |
| Siphonings per Hour | Rate | 4–6 |
⚠️ Warning: Ethanol-toluene solution is flammable and toxic. Avoid inhalation of vapors and contact with skin. Perform all steps in a fume hood.
📊 Calculation and Reporting
Calculate the ethanol-toluene soluble matter as a weight percentage relative to moisture-free wood using the formula:
Ethanol-toluene soluble matter (%) = (W2 / (W1 × P)) × 100
Where:
W2 = weight of dried extract (g),
W1 = weight of air-dry test specimen (g),
P = proportion of moisture-free sawdust in the air-dry specimen (from drying step).
Report the result as weight percentage of ethanol-toluene soluble matter in moisture-free wood. This value indicates the content of waxes, fats, resins, and other extractives.
❓ Frequently Asked Questions
🔍 What does the ethanol-toluene extract represent?
It represents the soluble materials not generally considered part of the wood polymeric structure, primarily waxes, fats, resins, oils, tannins, and some water-soluble substances.
💡 Why is the ethanol-toluene mixture used?
The mixture effectively extracts a broad range of organic and some inorganic components, providing a comprehensive measure of extractives in wood.
⚡ What is the significance of the siphon rate?
The siphon rate of 4–6 per hour ensures optimal contact between the solvent and specimen, maximizing extraction efficiency.
📌 How is the moisture-free proportion determined?
A separate test specimen is dried at 100–105°C until constant weight, and the ratio of dried mass to initial mass gives the proportion of moisture-free wood.