21. They took with them all the heavy photographic equipment they needed to produce iodinated collodion negatives. 22. Silver burns were so common that collodion photography was called " the black art ." 23. As long as the collodion remained at least partially wet, it retained some of its sensitivity. 24. The collodion process was used on a glass photographic plate to capture an image on the plate. 25. It was composed of 10 % camphor, 45 % nitroglycerine and 45 % collodion ( nitrocellulose ). 26. Parkes patented his discovery after realising a solid residue remained after evaporation of the solvent from photographic collodion . 27. The wet plate collodion process has undergone a revival as an historical technique over the past few decades. 28. As with all preceding photographic processes, the wet-collodion process was sensitive only to blue light. 29. Typically, methods involved coating or mixing the collodion with a substance that prevented it from drying quickly. 30. This method became known as the'wet-plate collodion 'or'wet collodion'method.
