The tintype is one of the earliest photographic processes, popular in the 1860s and 1870s. A light-sensitive emulsion is coated onto a black metal plate, exposed in the camera while it's still wet, then immediately developed in the darkroom. Using the metal plate revolutionized the art: photographers were now free to wander about the country, documenting the Civil War and westward expansion.
The tintype is making something of a comeback in recent years, as a new generation of photographers discovers the process and its one-of-a-kind results. CJ Harker, a photographer from Philadelphia, recently visited the Wake Forest art department to teach the tintype process to students in John Pickel's alternative processes class.
The technique for smoothly coating the plate with the collodion emulsion and then infusing it with silver nitrate takes quite a bit of practice to perfect. CJ prepares the chemistry before class, then demonstrates how to coat and sensitize a 4x5-inch metal plate. The resulting emulsion is not very light sensitive - it has an ISO value of about 1 - and CJ can use a red headlamp and regular darkroom safelighting for much of the process.
CJ Harker brought his Eastman portrait camera, an 8x10-inch folding wooden view camera with a massive Pinkham & Smith portrait lens. The camera is framed and focused using a ground glass plate on the rear, then focus is confirmed with an 8x loupe. The exposure is made by removing the lens cap, then pressing a button on a large flash power pack to trigger the flash.
Coating the plate and developing both require the same hand motion: the plate is held flat on the fingertips, the chemistry is poured on top, and the plate is turned and twisted to get an even coat. When developing the plate, this movement has to be very fast and precise - the developer works almost instantly, and any unevenness or missed areas will ruin the final image.
After the plates have been washed and then dried overnight, the students can varnish them to prevent oxidation. The varnishing process uses the same tricky pour-and-twist motion, of course.