This may not be ontologically relevant, but it's an interesting article on the conservation of the wood panels used for pre-canvas paintings.
Onward and Upward with the ArtsThe Flip SideThe secrets of conserving the wood behind an early masterpiece.by Peter Schjeldahl
November 29, 2010 .Peter Schjeldahl, Onward and Upward with the Arts, “The Flip Side,” The New Yorker, November 29, 2010, p. 42
Read more http://www.newyorker.com/reporting/2010/11/29/101129fa_fact_schjeldahl#ixzz170AX9olb
Unfortunately, you need a digital subscription to read the whole article, but it should still be on newstands for a day or so.