So here’s the second installment to my little series on film development. Today, I will talk about the various chemicals that one can use.
The most obvious chemical that one needs is the developer. After an exposure is made on a negative, a so-called latent image is formed on the film emulsion, where only a few crystals out of millions are reduced. This image is NOT visible to the eye, so do not, under any circumstance, open up the camera to look for an image (that’ll only overexpose all your images that are sitting out unprotected). From what I understand, the developer essentially intensifies the latent image on the film. This process reduces the silver halide on the emulsion to silver, which is what appears black on the film. The reaction is time-dependent and non-linear, so one must be careful about development time if one wants to have the full tonal range (overdeveloped film will have a lot of dark areas, and proportionately less white/light areas than a properly developed one).
There are numerous developers out in the market, but some of the more popular ones include Ilford ID-11, Microphen and Preceptol, as well as Kodak D-19, D-76 and HC-110. I personally use an HC-110 syrup for all my development needs, and this is a really good resource for using HC-110 with popular film types. One thing to note is that developers are fairly reactive, and will degrade with time. It is good to keep it in an accordion style container to prevent reaction with the oxygen in the atmosphere.
The stop bath is an acidic chemical bath that is used to stop the action of the developer after it has been poured out. Developers have been designed to work under only alkaline condition, so the introduction of the acid will neutralize and acidify the residual solution, and stop the reaction immediately. Alternatively, water can be used to wash the negatives, though this results in an indeterminate duration and extent of further development.
The fixer does what its name suggests: it prevents the negative from undergoing further changes (i.e. to keep it fixed in its current state). This occurs by removing the unreacted silver halide, which prevents further formation of silver via a reduction reaction. The fixer typically contains some sort of thiosulfate, which explains the slightly unpleasant smell. It is also important to completely remove the fixer after fixing, since it can cause undesired chemical reactions on the negative. Some common fixers are the Ilford Rapid Fixer and Hypam. I use a rather unusual fixer for my work because it is extremely cheap. It is the Kodak Flexicolor Fixer, which is meant for the C-41 process, but appears to work great. I haven’t had any problem at all, though I cannot guarantee the archival properties of this approach.
The wetting agent is the last chemical needed. It is essentially a detergent, and is used to prevent water marks from forming on your newly developed negatives. Some people recommend using a sponge/squeegee to remove excess water, though given the softness of the emulsion layer right after development, I will recommend against it. You can get PhotoFlo for less than ten bucks, and it will last you a very long time (you get 500mL, which should be good for up to 100 rolls of film).
So, there you have it. The list of chemicals is pretty short, and some people like to experiment with different chemistry to get different film looks. I don’t bother with that much, though. Next time, I will talk more about the actual steps needed to develop a roll of film!