Negative Tintypes and Challenges in the Process

   On the battlefield the wet plate process lends to unpredictable results. In comparison to the plates from a studio setting in which the images are more consistent and refined, pictures created outside in the field result in numerous negative results. When made outdoors the plates and chemicals are subject to many uncontrollable variables in the process. Some of these include lighting, temperature, and humidity. A photographer may have 3 plates, each coated at the same 20 minute interval, and each then exposed and then developed within a 20 minute interval. However none of the three final images may be the same.These are some of the major issues that war photographers also faced in the 1860's.

   If during coating the plates the humidity shifts, then so does the state of the emulsion. More humid air will make the emulsion sticky and cause adhesion problems. Less hunidity will make it drier, and create better fixation to the plate. Temperature also factors into the equation. A degree warmer or colder also dramatically affects the image emulsion by changing the adhesion stability to the plate, the contrast of the mixture and the overall sensitivity to light. Ideally the emulsion should be coated warm onto the plate, then the plate drained and momentarily chilled if possible to set up. 

   With the plate in the camera the factors are still prone to change. If the lighting from above shifts, so must the exposure, which is the amount of light from the focused image from the lens that reaches the plate inside the camera. The exposure is easy by itself to compensate for, simply adjust the time the shutter is open. However a warm humid breeze may pass by while exposing your plates. If so, the state of the emulsion on the plate changes, becoming tackier, less stable, more contrasty.

   These variables apply to not just the plates but also the chemicals. If the mixture of a developer warms or chills, by even a degree, the contrast of the final image changes. If the humidity shifts so does the density of the chemistry. The chemistry temperature also effects the adhesion stability. If its too warm the emulsion may begin to come off; too cold and the image may not develop sufficiently. While all these possible combinations of variables become exponentially boggling, there are still more factors that will effect the image. If the time from camera to developer is different between shots, then the final image will be different than the one before it. Last but not least, after the coating, exposure and development, is the drying process. Any environmental conditions that change during the final drying of the plates can affect factors such as smoothness of the plate, or a glossy or matte surface. The challenge of taking photos in the battlefield in the mid 1800's was not an easy task. A photographer needed to not just know how to take a picture, but be a chemist, and even be able to predict the subtle changes in the weather.

   Below are some of the negative results of tintypes taken in the battlefield. Orange-peeling of the emulsion, poor exposures, adhesion problems and speckling were just a handful of difficulties encountered. One of the strangest plates, the third one below, looks as if the emulsion actually combusted into a fireball on the surface of the plate somewhere in the process. The reason for this plate is unexplained, although more than one plate has turned out this way. The second example below shows a plate that was fogged before the development, meaning it somewhere got a flash of light over the plate, perhaps from a small light leak in the portable darkroom, or maybe a bad film holder. The final plate illustrates a recurring problem of orange peeling of the emulsion. Sometime during the development a perfectly smooth plate forms mountains and valleys in the emulsion.  The first plate below is the easiest to explain. It is an example of what happens when the slippery plate falls into the grass somewhere between the developer and fixer.