Slack Wax DAO (Deasphalting Oil)

About This Product

Slack Wax DAO, derived from the deasphalting oil fraction of lubricating oil refining, is the heaviest and most complex grade within the petroleum slack wax family, classified under CAS No. 64742-61-6. The deasphalting process involves the removal of asphaltenic compounds from heavy residual oil using light hydrocarbon solvents such as propane or butane, yielding a high-molecular-weight oil stream — and the wax crystallised from this stream constitutes Slack Wax DAO. Its dark amber to light brown colour on the ASTM D-1500 scale (maximum 5.0) reflects the presence of higher molecular weight aromatic and naphthenic compounds. Solvent deasphalting as an industrial process was pioneered in the 1930s and 1940s to recover quality base oil components from vacuum residue, with the DAO wax fraction initially treated as a processing byproduct. By the latter half of the 20th century, refiners recognised the commercial value of this heavy wax stream and began marketing it alongside LMO, SPO, and MMO. DAO remains the most specialised of the four grades, with demanding applications that leverage its exceptional hardness and high melting point. With a melting point of 69–74°C and Bio Green Wax's customised oil content range of 5–20% — the most controlled specification of all four grades — Slack Wax DAO offers the highest structural integrity in the family. Its viscosity of 18.5–22.5 cSt at 100°C is approximately 5x that of LMO, with significant implications for pumping, heating requirements, and downstream processing. An interesting fact: Slack Wax DAO is one of the primary feedstocks for microcrystalline wax — a high-value refined product used in pharmaceuticals, food coatings, cosmetics, and precision applications — making it a strategically important upstream raw material despite its dark appearance. Industrial applications include microcrystalline wax production as primary feedstock, heavy rubber and tyre compounding, construction waterproofing membranes, pipeline and anti-corrosion wax coatings, bitumen and road asphalt modification, heavy-duty board moisture barriers, and electrical cable insulation compounds.