His portraits of merchants presented them either standing or seated in a river landscape or with an interior with a view through a window. Several examples are extant and this work and others of similar composition are illustrated in Thierry Audric, Chinese Reverse Glass Painting, 1720-1820 (Peter Lang, 2020) p. 126-133. See also Portrait of a Western merchant on the China coast, reverse glass painting, 25.9 x 20.6 cm, Hong Kong Museum of Art; Sotheby’s New York, 20th January 2016, lots 231 and 706; Martyn Gregory, Catalogue 81, London, 2005-2006, no. 117, and Catalogue 78, London, 2002, no.108. Another example can be found at the Lady Lever Art Gallery, Port Sunlight (acc. no. LL 8824).

Patrick Conner gives further details about Spoilum's portraiture in 'The Enigma of Spoilum and the Origins of China Trade Painting,' in The Magazine Antiques, March 1998, vol.CLIII, p.418, no.3.

The earliest dated reverse glass portrait by Spoilum is of Captain Thomas Fry, dated 1774. It is thought he began painting oils on canvas in the 1780s, being possibly the first Chinese artist to do so, instead of using the more usual Chinese style of inks on paper or silk. As Guangzhou was the only port at which Westerners were allowed to trade at this time, such works are likely to have been produced for the Western market. Spoilum had connections with not only the British, but also with the American trade through Guangzhou, and a number of his works are now held in American collections including the Peabody Essex Museum, Salem, Massachusetts.

Crossman describes ‘the characteristics of Spoilum’s distinctive style’ to be: ‘the slight smile to the mouth… one eye slightly higher than the other, and the crisp delineation of the facial features.’ (Carl L. Crossman, The Decorative Arts of the China Trade: Paintings, furnishings and exotic curiosities (Antique Collectors’ Club, 1991), p. 36.)