The wax sample is melted under controlled conditions
The refractive index of the molten wax is measured
The oil content is calculated from calibration data relating refractive index to oil concentration
The presence of oil changes the refractive index of the wax, allowing the oil level to be quantified.
The ASTM D612 is used for fast and repeatable for refined paraffin waxes, suitable for low oil contents and common in wax quality control and specification testing.
Typical applications are fully refined paraffin wax, semi-refined paraffin wax, wax used for candles, packaging, cosmetics, and coatings.
This test niethod determines the carbonizable substances in pharmaceutical paraffin wax whose quality is prescribed by the U.S. National Formulary. Such waxes have a melting point between 117and 149°F (47 and 65°C), as determined by Test Method D 87.
Precision
Since this is a pass-fail test, no precision or bias estimate can be made.
Test
Five mL of melted wax are treated with 5 mL of concentrated Nitrogen-free sulfuric acid at 1580F(70"C). The color of the acid layer is compared with that of a colorimetric reference standard. If the color is not darker than the standard, then the wax is reported as passing the test.
