ABSTRACT
In 1889, Dr. W.W.J. Nichol patented kallitype processes based upon the argentotype work. The early kallitype processes never achieved great popularity. Kallitype with platinum toning was marketed as being cheaper than platinum printing, and a paper containing both silver nitrate and platinum was commercially available. Kallitype developed a reputation for fading and instability, primarily due to poor processing techniques. Today the kallitype sensitizer is comprised of ferric oxalate and silver nitrate. Since kallitype is a develop-out process, the resulting image after exposure is just a whisper. Vandyke brown uses the reduction of ferric to ferrous through exposure to UV light. Ferric ammonium citrate is used as the ferric ingredient, and silver nitrate, tartaric acid, and sometimes gelatin are also part of the sensitizer. Argyrotype is a printing-out process. The biggest issue for argyrotype practitioners is the availability of silver sulfamate.
