The cost and logistics of conserving, storing and retrieving thousands of lithographic stones was of course immense; add to that the cost of the stones – £5 each, perhaps $1000 in today's values – and the virtue of saving the artwork onto glass photographic plates maybe 6 inches square, and having half-a-dozen stones in stock, which could be cleaned, prepared, and photographically embossed over and over again, being resurfaced as required, becomes obvious.