Darkroom Chemicals 101

March 09, 2015  •  Leave a Comment

Darkroom Chemicals 101 by Tim LaytonDarkroom Chemicals 101 by Tim Layton As a film photographer, one of the benefits, in my opinion, is the hands-on approach that you have in regards to your final print. 

I personally specialize in black and white photography so my thoughts on the chemical side of photography will be slanted in that direction. I process all of my own films, both color and black and white either by hand or in my Jobo which allows me to process film and color RA-4 prints up to 24x20. 

First off, I simply enjoy handling and developing film.  I like the manual and physical process of handling my films ranging in size from 120 roll film up to 11x14 sheet film.  From the time that I load the film and expose it in the field to the time that I create my print, I have a lot of thoughtful time to consider and ponder my creative possibilities.  I mention this because I think this is a unique advantage of using film and in particular large format sheet film.  I personally find 120 roll film and large format sheet film the easiest to work with.  The few times that I do handle small format 35mm film I find it much more difficult than the larger films because of the smaller format. 

The process of traditional photography and its magic never gets old to me.  I’ve used plenty of non-film based cameras and while they can be the right tool for certain jobs, I will forever love the process of developing real film and printing in the darkroom. 

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The Chemistry

You don’t need to be a chemist to be a successful black and white film photographer, however, you do need to at least know the basic chemicals for developing and printing and their associated relationship and impacts on your creative process.  After you learn the basics and do it for a while it becomes second nature to you. 

It all begins with our original exposure of the film where the latent image is waiting to be activated and altered by the silver halide crystals.  The image will ultimately be reduced to metallic silver by your developer.  The physical and chemical process is part of why I love traditional black and white film photography.  Not only do I have total control over the development and printing process from an artistic perspective but I get the personal satisfaction of having made something with my hands.  I think this is something that we miss in the high-tech world today.  I personally think as we get further into the technology world and Internet social media culture where we are producing fewer things, people as a whole will start to miss the inherent beauty and satisfaction of holding a real print in their hand versus looking at a pitiful and often over manipulated copy on their phone or computer.  Keep an eye out for me because I will be the old guy standing next to you in line with a bald head and crazy long beard wearing some very comfortable overalls and hiking boots.  Remember to say hello because I don't have any devices that can receive text messages.  Instead of spending my life on a computer or the phone I make original darkroom prints with my own two hands.  

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The reduction to metallic silver takes place when we are printing as it does with our films in the darkroom.  You will have more density in areas that received the most light in your exposure.  The key point to really remember about your density is your developer (time and temperature) and your agitation technique will play a big role in the final outcome.  You need to keep this in mind when you standardize your development times.  For example, the time required to develop by hand in a tank versus using a rotary system like a Jobo will be different because of the differences in agitation and the temperature drift when using a hand tank.  

You can probably guess that we need to get rid of the residual silver halides that didn’t get activated so we put our film in an acid stop bath and fixer to halt the development process and also fix the image onto the film/paper thereby neutralizing the alkaline in our developer before removing the remaining silver halide from the emulsion. If we didn’t remove the remaining silver halide from our film/prints you can probably guess they would be activated by light over time and ruin your film/print.

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The Developer

Silver gelatin print by Tim Layton I think Ansel Adams said it best when he recommends the use of as few developers as possible.  I’ve seen people wildly use developers and have no idea how to control the outcome because too many variables are involved (e.g., developer, time, temp, agitation, etc).  I’ve talked to people that have no idea why they are using their current developer. If there is any advice you should ever take it would be to focus on one developer until you master it and I am willing to bet that a single developer could accomplish the vast majority of your objectives.  You may never need another developer ever again if you choose wisely.  Spend your time creating photographs, telling stories or learning more about composition as opposed to wasting your time chasing the perfect developer.  It is a fruitless monster that eats your time and has no return.

When you choose your developer one thing I must stress is the consistent use of temperature throughout your process unless you are using Diafine which has a broad temperature range.  For more reasons than I can get into in this article, you should strive for the standard temperature of 68F/20C.  At warmer temperatures, the film emulsion swells in addition to other factors that you should avoid.  If you use roll film and develop in tanks or you are a large format sheet photographer and develop in trays the same principles still apply.  A water bath is a good way to help control your developer temperature.  If you use steel tanks for development these are good conductors and respond very well to temperature adjustments.  A water bath is just a tray or sinks of water at a controlled temperature to help stabilize the temperature of your tank or trays.  You can use larger darkroom trays or even pans or Tupperware from your kitchen.  One of the best investments you can make is a quality thermometer for use in your darkroom.  The gold standard, in my opinion, is the Kodak Type 3 process thermometer.  You can find them on e-bay for a very reasonable price (~ $100 USD).  This is a tool that can make or break you and it will be something that you use for a lifetime so don’t cut corners on your thermometer.

A good test for roll film users is to measure your temperature at the start of the development process and then again at the end of your cycle.  Just mix up some developers, shoot a roll of sample images and perform the test.  You want the test variables to be as close to your actual process as possible.  If you have a difference of more than 1 degree then you need to find a way to minimize this gap in your process.  A water bath as mentioned above is a good choice.

Stop Bath

After development, comes the stop bath.  The job of the stop bath is very simple.  It is to stop the development of your film and to preserve the life of your fixer.  The stop bath process is typically only 30 seconds so it is fast and easy.  I use an acid stop bath as opposed to a water stop bath for my traditional developers and the only exception to that is when I use Pyro HD.


Between the fixing and washing of your film, these are very important steps to remove all the unwanted silver halides from your finished negative.  If the residual halides are left on our negatives and prints for that matter then our film and paper will deteriorate over time and this is not a desirable outcome.  As you can imagine the silver halides are light-sensitive and if you left them on your film and prints that would not be good.  The stop bath and fixer also neutralizes the alkaline in our developer which is important as well.

I hope you can use this information to help build or confirm your base of knowledge in traditional black and white film photography. Share your knowledge with others and try and help as many people as you can.

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