Study of "Susanna Al Bagno" by Francesco Hayez
Time: 15 hours
Image of "Susanna Al Bagno" referenced: http://imgur.com/AiZqd
Information on original painting: http://www.nationalgallery.org.uk/paintings/francesco-hayez-susanna-at-her-bath
After finishing the study, I looked up the painting and found that the picture I referenced is both of low quality and of the painting before its current restoration. Oh, well. Next time I will make sure I have the best references.