A night of constant stomach pain and tremors, like being punched in the abdomen by a million pesky elves. I started by tracing over the 'sleep' painting idea and researching various copyleft licences to apply to my free software one day, then into a steady day underpainting the Rachel Hudson painting.
The yellow background makes the flesh look more violently violet than it should (and more violet that it actually is in real life - that's auto-white-balanced photography for you).
I stuck generally to the colour study, my typical flesh tones of MH Naples Yellow (PBr24 that is, Titanium Antimony Chromium Oxide; not the historic Naples Yellow), light red, mars violet, black. Dali said that Venetian red was superlative for flesh, but I find the violets of mars violet essential at times, and the rosy pinks of light (English) red too. Some of my best flesh paintings (the hand in The First Grasp of Rebirth, the figure in The Death of Man) are simply white, black, light red. I've rarely used Venetian red for flesh. This is also because, I think, red glazes over yellow were less reliable and transparent than yellow over red historically. I often prefer a yellowish underpainting and a red glaze, if glazing. This is partly because it fits a secondary to primary layer format. If you think of glazes as transparent filters, you'll reason that all colours filter to primary. For the best glazing then it can be best to start with whites, then secondary colours (yellow, violet, cyan), then primary (red, green, blue).
Of course we don't have perfect primary hues in paint (thank the heavens!), this is a rough guide. This manifests as red over yellow seems to work better than yellow over red. There are caveats though, there are no always-correct answers. For a start, paints reflect as well as transmit, and the top most layer will give a reflection of that hue, and the best colours for this are light ones, so here yellow would trump red.
