	Fortunately, a management buyout by Joe Katz put Vellum and Parchment Works Celbridge back in operation. Vellum these days is normally supplied for orchestral tympani heads -sheets of the nature required for the Book had to be painstakingly and rigorously prepared by hand -and then artists had to face the nightmare of working, one chance only, on an unfamiliar surface, a living material which stretched and shrank as it was wet or dry, a subtly uneven surface containing minute amounts of natural oils. 