I'm studying calotypes and cyanotypes.
Their major contribution to the development of photography was the fact that they could be easily copied. The original negative could be used to create as many positive copies as wanted, with a process called contact printing.
However for contact printing to work as desired, the original negative had to be translucent. I don't understand how it was made translucent.
Talbot made his first successful camera photographs in 1835 using paper sensitised with silver chloride, which darkened in proportion to its exposure to light......In late 1840, Talbot worked out a very different developing-out process, in which only an extremely faint or completely invisible latent image had to be produced in the camera, which could be done in a minute or two if the subject was in bright sunlight....The light-sensitive silver halide in calotype paper was silver iodide, created by the reaction of silver nitrate with potassium iodide...... The calotype process produced a translucent original negative image from which multiple positives could be made by simple contact printing.
I don't get if the paper initially used it's itself translucent or it's a developing process that makes it translucent.