Slack Wax is by-product of the production lubricating oils and mixture of paraffin wax and oil originated from petroleum crude oil. During the production of Group I lube base oil, first the feedstock has to go through solvent extraction process to remove aromatics and the resultant product is called raffinate.
The raffinate is then diluted with solvent like methyl-ethyl ketone (MEK) to lower its viscosity to improve low-temperature filterability. The diluted oil is then chilled to -10°C to -20°C. Wax crystals will form, precipitate and removed by filtration. The removed wax becomes Slack Wax.
Slack wax is naturally brown in color and depending on the viscosity of the lube oil being de-waxed it is categorized in two types of light and heavy. In light grades the melting point is 50-52˚C where in light grades the melting point is 53-55˚C is the heavy grade and their oil content ranges from 5.0% to 35%.

H-Slack Wax
H-Slack Wax Specification
Result Test Method Unit Characteristic
H-16 H-14 H-12 H-10 H-08 H-05 H-02 Grade
5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 5.5-7.5 ASTM D-445 mm2/s (cSt) Kinematic viscosity at 100°C
14-16 12-14 10-12 8-10 5-8 2-5 Max 2 ASTM D-721 % wt Oil content
810-840 820-850 810-840 810-840 810-840 810-840 810-840 ASTM D-4052 Kg/m3 Density at 15.6 °C
240 240 240 240 240 240 240 ASTM D-92 Flash point
3 3 3 3 3 3 3 ASTM D-1500 Color@ 70 oC (max)
60 60 60 60 60 60 60 ASTM D-938 Congealing Point (0C)(min)