The wet collodion technique reigned in the 19th century
Collodion is a term that comes from the Greek word kollṓdēs , translatable as "sticky." It is a solution derived from cellulose and used as a binder .
Nitrocellulose in alcohol
It should be noted that cellulose is a polysaccharide (a saccharide composed of many monosaccharides) that makes up the wall of a plant cell. When a product derived from this polysaccharide is dissolved in an organic solvent, collodion is obtained.
Collodion is usually produced from the dissolution of nitrocellulose in alcohol and ether . Nitrocellulose, meanwhile, is a cellulose derivative that is nitrated (that is, a nitro group was introduced).
wet collodion
Collodion is used to prepare photographic plates . The French photographer Gustave Le Gray ( 1820 – 1884 ) is noted as one of the pioneers in the use of the method known as wet collodion .
For the development of wet collodion, the collodion must be placed on a glass plate . This plate must always be kept moist while images are being taken and developed.
Development with wet collodion was carried out using ammoniacal iron sulfate . The photo could be developed in about thirty seconds, which was an advantage over other procedures . However, it was common for the glass plates to break or get scratched.
Development of wet collodion
Along with Gustave Le Gray, the British sculptor Frederick Scott Archer is mentioned as one of the two creators of this procedure, which was also used in the mid-19th century by the Polish military captain known as the Count of Lipa .
Since 1855, wet collodion achieved overwhelming popularity compared to the rest of the techniques . Other very important photographers who used it in their work were J. Laurent and Charles Clifford . Almost three decades later, with the arrival of instant photography (with gelatin-bromide plates, instead of collodion), it began to lose importance in the market, although it would still take many decades until all graphic workshops stopped using it. .
Elastic collodion
The so-called elastic collodion , meanwhile, is used in pharmaceutical formulas. Being sensitive to light and volatile , compositions that include this element are usually prepared directly in the remedy container, which is closed hermetically.
The elastic collodion is formed by mixing five parts of official pyroxylin, fifteen of alcohol and eighty of ether, all combined with castor oil so that it does not crack. It is a liquid with a syrup-like consistency, transparent and with an unmistakable smell of ether. It can be mixed with it and with alcohol, in addition to being insoluble in water .
Dry plates were the first opponent of wet collodion
It has a high degree of volatility and flammability , as well as a significant sensitivity to light . For this reason, elastic collodion and any formulation thereof should be stored in topaz glass bottles that have been hermetically closed, away from light and away from any heat source. The processes in which it is used must last a short time so that ether or other highly volatile constituents are not lost.
The use of a single container is usually respected for the preparation of compositions with elastic collodion and for their subsequent use , so it must have the appropriate volume and an airtight closing mechanism, in addition to including a spatula to make it easy to dispense. It is usually added at the end of the process precisely to respect all these conditions. Once finished, it is shaken so that the formula becomes homogeneous .