His portraits are known for their smooth, glass-like finish and bright colours. He often painted members of the British royal family and high-ranking nobility, including Queen Caroline and the Duke of Marlborough. Zincke gave his sitters a specific look, usually with large eyes and a clear, porcelain complexion. Because enamel is essentially glass fused to metal, these works do not fade or crack like traditional oil paintings. He was extremely successful and operated a busy studio in Covent Garden to meet the demand from the aristocracy.

Modern collectors appreciate these works for their sharp detail and historical accuracy. The miniature format creates a personal connection with the subject. Prints of his portraits offer a clear view of 18th-century fashion, from lace collars to military armour. They provide a sense of Georgian history without the dark, heavy tones found in many period oil paintings. The technical precision of his method makes these images ideal for display in a contemporary home.