"The calotype negative process was sometimes called the Talbotype , after its inventor. It was not Talbot's first photographic process (introduced in 1839), but it is the one for which he became most known. Henry Talbot devised the calotype in the autumn of 1840, perfected it by the time of its public introduction in mid-1841, and made it the subject of a patent (the patent did not extend to Scotland). The base of a calotype negative, rather than the glass or film to which we have become accustomed, was high quality writing paper. The sheet of paper was carefully selected to have a smooth and uniform texture and, wherever possible, to avoid the watermark. The first stage, conducted in candlelight, was to prepare what Talbot called his iodized paper. The paper was washed over with a solution of silver nitrate and dried by gentle heat. When nearly dr
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