Youqua was an export painter active from the 1840's to the 1880's and who set up workshops in Canton and Hong Kong under the name 'Yeehing'. See G. Clunas, Chinese Export Watercolours, 1984. For further discussion on pith paper (derived from the pith of Tetrapanax papyrifera) paintings, see C. L. Crossmann, The Decorative Arts of the China Trade, Woodbridge, Suffolk, 1991, pp.200-202, and colour plate 70 and pls. 105 and 106 for examples of Youqua's pith paper work and label.
A similar album was sold in these rooms on 20 November 2007, lot 227.