Complex sentence: DeCosta believed his medium had similar qualities to Maroger (Jacques Maroger) medium, the supposed medium of the Old Masters; because Maroger medium must be cooked with lead, Turco lacked its inherent danger and had a similar, if not faster, drying time.
Split into simpler sentences: DeCosta believed his medium had similar qualities to Maroger (Jacques Maroger) medium, the supposed medium of the Old Masters. Because Maroger medium must be cooked with lead, Turco lacked its inherent danger and had a similar, if not faster, drying time.