Collodion
Collodion is a flammable, syrupy solution of nitrocellulose dissolved in ether and alcohol, often with the addition of alcohols. It was discovered around 1846 by the French chemist and writer Louis Ménard. The solution dries to a celluloid-like film and was initially used for medical purposes as a dressing, but its application expanded significantly in the mid-19th century with the advent of photography[6][10].
In photography, collodion is best known for its use in the wet plate collodion process, a technique invented by Frederick Scott Archer in 1851. This process involved coating a glass plate with iodized collodion, sensitizing it in a bath of silver nitrate, exposing it while still wet, and then developing it. The process required the photographic material to be coated, sensitized, exposed, and developed within about fifteen minutes, necessitating a portable darkroom for field use. It was capable of producing highly detailed and reproducible images, which made it popular for portrait, landscape, and architectural photography from the 1850s through the 1880s[10][11][12].
Collodion was used in several variations of photographic processes. Besides the negative process for creating prints on paper, it was also used to produce direct positive images on glass, known as ambrotypes, and on metal, known as tintypes or ferrotypes. These direct positive processes were cheaper and faster than creating daguerreotypes, another popular photographic method of the time, and did not require a negative[10][11][12].
Despite its advantages, the wet plate collodion process had several drawbacks. It was sensitive only to blue light, which made it difficult to differentiate between warm colors in photographs, and skies often appeared white or very light due to the overexposure of the blue light. Additionally, the entire process had to be completed quickly before the collodion dried, which was challenging and required the photographer to have a portable darkroom[14].
The wet plate collodion process was eventually superseded by dry plate processes and gelatin silver processes in the late 19th and early 20th centuries, which were more convenient and allowed for longer exposure times. However, the wet plate collodion process has experienced a revival in the 21st century as a historical technique among fine art photographers and enthusiasts for its unique aesthetic and handcrafted individuality[12].
Collodion is also used in medical applications, particularly in attaching electrodes to the scalp for electroencephalography (EEG) due to its strong adhesive properties and resistance to moisture. However, its use can cause discomfort and irritation due to the strong solvents required for its removal[16][17].
Citations:
[1] https://cool.culturalheritage.org/albumen/library/monographs/monckh/chap03.html
[2] https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/atlas_collodion.pdf
[3] https://www.mvapmed.com/MSDS_Forms/CollodionSafety.pdf
[4] https://www.alternativephotography.com/wet-plate-collodion-process-ambrotypes/
[5] https://www.mccrone.com/mm/flexible-collodion-in-particle-analysis/
[6] https://www.chemeurope.com/en/encyclopedia/Collodion.html
[7] https://nj.gov/health/eoh/rtkweb/documents/fs/1366.pdf
[8] https://www.mvapmed.com/collodion-u-s-p-.html
[9] https://ehslegacy.unr.edu/msdsfiles/22200.pdf
[10] https://en.wikipedia.org/wiki/Collodion
[11] https://www.britannica.com/technology/wet-collodion-process
[12] https://en.wikipedia.org/wiki/Collodion_process
[13] https://www.sentryair.com/blog/industry-applications/chemical-solvents/collodion-adhesive-possible-health-effects-fume-extraction-recommendations/
[14] https://notquiteinfocus.com/2014/01/21/a-brief-history-of-photography-part-4-wet-plate-collodian/
[15] https://www.khanacademy.org/humanities/becoming-modern/early-photo/early-photo-england/v/wet-collodion-process
[16] https://seermedical.com/collodion-adhesive
[17] https://www.mvapmed.com/MSDS_Forms/Collodion%20MD0002.pdf
[18] https://www.hnoc.org/virtual/daguerreotype-digital/wet-plate-process
[19] https://www.khanacademy.org/humanities/special-topics-art-history/creating-conserving/photographs/v/the-collodion