Lot 81414 – Spain, Local Post Madrid – 1853 3cu, three items, one trial exposure

1853 3cu, three items, one trial exposure on transparent photographic paper with annotations at base noting application of an unspecified chemical, an exposure time of 1min. 30s and at 15 degrees temperature, another exposure also on celluloid with image reversed, and a fine glass support cliché with mirror image in black. A very fine and unique range of production materials for this rare stamp.