This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
Composed of 2 parts washed graphite, 2 red-lead, 1G freshly-prepared cement, 16 barium sulphate, 4 lead protoxide, 2 alcoholized white litharge. The paint must be put on as soon as the roofing is securely fastened, choosing the dry season and a sunny day. Care must be taken to put it on well over the joints ; it is recommended that an extra coating should be given to the portions that overlap each other, so as to render them water-tight. As a rule, two coats are put on. The first, whilst still wet, is covered with an even layer of fine dry sand sprinkled over it through a sieve. This is done bit by bit, as the roof is painted, so as to prevent the workmen stepping on the wet paint. The second coat is put on about a week later, the sand which has not stuck fast being first swept off. The second coat is not sanded. It is merely intended to combine with the under-coat and form a durable waterproof surface, which will prevent the evaporation of the tar-oil, the usual cause of the failure of carton-pierre roofing, and present a good appearance as well.