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D590-93 – Standard Test Method Technical Guide
ASTM D590 – 93 (Reapproved 2002) provides a standardized gravimetric procedure for the quantitative determination of total petroleum wax in wax-impregnated papers. This method is essential for evaluating papers referred to as “dry waxed” or “waxed” papers, providing a direct measure of the wax content that correlates with the paper’s resistance to aqueous liquid penetration. The standard is approved for use by agencies of the Department of Defense.
📐 Scope and Limitations
The test method explicitly applies to wax-impregnated papers and products manufactured from such papers. It determines the total amount of wax materials extracted under the specified conditions. A critical distinction is made for wax-sized papers, which are excluded from this method’s scope due to the presence of rosin or other materials soluble in the extraction solvent (toluene), which can severely impair the accuracy of wax measurement.
Furthermore, the method does not differentiate between “surface wax” and “total wax.” It is the responsibility of the user to establish appropriate safety and health practices, with specific precautionary statements detailed in Section 8 of the standard.
⚠️ Safety Precaution: Toluene is a hazardous solvent. Specific precautionary statements are given in Section 8 of the standard. Users must ensure proper ventilation (e.g., fume hood) and follow all laboratory safety protocols.
⚙️ Apparatus and Reagents
The procedure relies on a Soxhlet-type extraction assembly. The standard permits the use of either a traditional Soxhlet glassware setup or a high-efficiency assembly like the Soxtec System HTt. The specified extraction solvent is toluene. A pure cellulose extraction thimble is required. Supporting equipment includes an electric heating mantle with a variable power source, an analytical balance, and a drying oven capable of maintaining 105°C. The standard also references crucial practices for sampling (D 585), conditioning (D 685), and terminology (D 1968).
| 🟦 Key Equipment | 📏 Specification |
|---|---|
| Extraction Assembly (Type 1) | Traditional Soxhlet: Tube, condenser, solvent reservoir |
| Extraction Assembly (Type 2) | High-Efficiency: Soxtec System HTt or equivalent |
| Extraction Thimble | Pure cellulose, suitable for Soxhlet extraction |
| Extraction Solvent | Toluene (reagent grade) |
| Heating Source | Electric heating mantle with variable power control |
| Drying Oven | Capable of maintaining 105 °C |
📊 Procedure and Calculation
The test specimen undergoes extraction in the assembly with toluene. Following extraction, the solvent is evaporated. Both the extracted wax and the extracted specimen are dried to a constant weight in an oven at 105°C and then weighed. The percentage of wax present is calculated based on the dry weight of the extracted wax or the dry weight of the extracted specimen. The result can be reported on either a dry sample weight basis or a conditioned sample weight basis, depending on the agreement between the user and the client.
💡 Procedural Note: The choice between reporting wax content on a “dry sample weight basis” or a “conditioned sample weight basis” must be clearly agreed upon by the interested parties conducting the test, as this directly affects the calculated percentage.
| 🎯 Critical Test Parameters | ⚡ Required Condition |
|---|---|
| Extraction Solvent | Toluene |
| Drying Temperature | 105 °C |
| Scope of Measurement | Total wax (does not differentiate surface vs. total) |
| Reporting Basis Options | Dry sample weight OR conditioned sample weight |
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D590-93?
The standard quantitatively determines the total amount of petroleum wax in wax-impregnated papers, including “dry waxed” or “waxed” papers, and products made from them.
💡 Can this test method differentiate between surface wax and total wax?
No. As stated in Section 1.3 of the standard, this test method measures the total amount of wax materials extracted under the conditions specified and does not differentiate between “surface wax” and “total wax.”
⚡ What solvent is specified for the extraction of wax in this method?
The standard specifies toluene as the extraction solvent for the Soxhlet-type extraction procedure.
📌 At what temperature are the extracted specimen and wax dried?
Following the extraction and evaporation of the solvent, the extracted wax and the extracted specimen are both dried at 105°C before being weighed.