Apocalypse Art competition and an experiment with shellac paper

The Apocalypse Art Prize is an initiative started by an artist in the USA and a rare platform for traditional art: the idea is to create an original triptych illustrating three different parts of the Apocalypse of St John (Revelation), using traditional media and drawing on the principles (but not necessarily the styles) of medieval manuscript illumination. The prizes are sizeable and there is still time to enter (closing date 31 December 2015) - but read the rules carefully, they are quite specific. I have been working on an entry for a while but have found it hard, as the specified size is a good deal larger than my preference and the need for the work to be postable restricts the options a bit. Gesso boards, whilst much the easiest to work on, are far too heavy, and vellum at this size would be far too expensive for a speculative piece. That just leaves watercolour paper, which is a pretty horrid surface for egg tempera: you can't change your mind about the design or obliterate the smallest mistake, and even the best quality watercolour paper (Fabriano hot press 600gsm in this case) has a 'hairy' surface which is not rewarding to work on. I tried various ways of reducing the absorbency and fibrosity, including surface sizing with alum and with gelatine. In the end I used a trick which I read about from a bookbinder, who uses it on endpapers to simulate the appearance of parchment. You stain the paper first ( I sponged on a mixture of glair and ochre pigments) and then paint it both sides with bleached shellac. This makes it a little more translucent, like vellum, and makes a smoother, less absorbent surface for the paint. Not good enough to allow one to scrape off mistakes, alas, but good enough for try-outs and ephemera when you want to avoid expense.