Wynn White irons out the difference between Kallitypes and Vandykes.
Is it a kallitype or a Vandyke?
To many the terms kallitype and Vandyke are synonymous and both simply mean a printing process where paper is coated with a mixture of a ferric salt and silver nitrate. To others the terms refer to two quite different processes. Who is correct?
The name Kallitype is made from the two Greek words, meaning beautiful and picture. In 1841 Henry Fox Talbot gave the name Calotype to his negative/positive salted paper process. The Kallitype process was invented much later by Dr. W. W. J. Nicol and dates back to 1889-1891 when he coated paper with a a ferric salt and silver nitrate solution and then exposed it through a negative and developed it.
I consider the term kallitype to mean the iron-silver nitrate process that requires a developer (developing-out paper or D.O.P.). A kallitype is made by combining equal parts of a 10% silver nitrate solution and a 20% ferric oxalate solution just before coating. The sensitized paper is then exposed and developed in a solution such as sodium acetate, sodium citrate, potassium oxalate or rochelle salts depending on the desired print color.
The Vandyke Print
The Vandyke print gets its name from its similarity in color to the deep brown pigment, Vandyke brown, used by the Flemish painter Van Dyck. Antoon Van Dyck was born in 1599 in Antwerp. In 1632 Van Dyck was invited to London to be court painter for Charles I. He was knighted Sir Anthony Vandyke in 1633. Therein lies the confusion in the two names.
Vandyke is based on the first iron-silver process, the argentotype, invented in 1842 by the English astronomer, Sir John Herschel.
I consider the term Vandyke print to mean the iron-silver nitrate process requiring no developer (printing-out paper or P.O.P.). It is made by combining silver nitrate, ferric ammonium citrate and tartaric acid to make a solution that keeps for up to a year or two. Paper is coated with the Vandyke sensitizer, exposed and then cleared in water.
Vandyke prints have also been referred to as sepia prints and brown prints. Although the actual color of the Vandyke print is closer to sepia than to Vandyke brown I would avoid using this term since I have seen everything from sepia toned gelatin-silver prints to ink jet prints referred to as sepia prints. One of the original uses of the Vandyke process was as a means of making copies that were referred to as brown prints. Some still refer to Vandykes as brown prints.
Although kallitypes and Vandykes are similar, both being iron-silver processes, they are distinctly different. Vandyke prints are simpler to produce and require less processing. Kallitypes on the other hand are more complicated to make but offer much greater latitude in contrast and image color.