M-Alchemy is the only lab in North America that develops 70mm and 65mm film for photographers.

You can also develop it yourself, or find someone else you can do it for you. Various options and tips are given on this page.

For both Mercury Works products and a collection of third-party vintage developing gear check out the Mercury 65/70mm Store.

While these are quite rare today, 116/616 film developing reels and tanks do exist. Because these formats utilize 70mm film, any 70mm film can be used, albeit only short lengths (up to 36 inches).

Photo courtesy of Bryan Chernick

This system acts like any other stainless steel inversion system.

An extremely easy way to develop 70mm, if you are just experimenting with smaller 220 lengths, is to adapt a 220 spiral and develop normally. It is possible to adapt both a 220 Patterson reel and a 2502 Jobo reel to accept 70mm film. Mercury Works makes adapters for both. With one you can easily (and reversibly) configure a standard Jobo 2502 reel for 70mm:

It can then be developed in a standard 2500 series tank, with standard inversion or, using far less chemistry, on a roller or rotary processor. This is my recommended method.

You can also do this (inversion only) with a Patterson inversion tank and standard 120/220 reels. If you combine parts from three reels as in the photo below, you can load 70mm and develop like 120.

If you use parts from two reels you can even avoid the adapter: https://youtu.be/f9REyP3gLjo?t=135

To limit your 70mm shooting to 220 lengths that can fit these reels, you can either limit how much you load in a cassette to approximately 23 turns. Or you can spool a full load and simply cut the film after a certain number of exposures (20 6x7 exposures, 24 6x6 exposures, etc.).

To develop full 15ft loads, however, you'll need a reel and tank designed specifically for 70mm. Here are some options:

Mercury Works offers a complete 65mm and 70mm long roll home processing system that takes up to 13ft of film and enables daylight processing. For 65mm film, use our specially made developing reel. For 70mm, use the 3rd party NDT 70mm developing reel. These reels are made for the medical community for developing X-Ray film. They are still available. They are fairly compact: at their largest point, they have a diameter of just 162mm. Like metal reels, these load from the inside out. The center column contains a clip to attach the end of your film.

The disadvantage of the NDT reel is that it only holds 13ft of film, just shy of a full 15ft cassette load. Still, it is easy to simply load 13ft loads. Just load the reel with your desired film, then test to discover how many turns on a cassette spool it takes for exactly that amount (this will vary depending on the thickness of the film).

This is the best system, developed by Jobo in the 1970s, but unfortunately discontinued by the 1990s. It consists of three parts:

• The 3035 Expert Drum: This is shorter than any other expert drum, but is compatible with any Jobo machine that accepts the Expert system. It uses the same caps as other Expert Drums.
• The 3075 5M Reel: This is a plastic reel that fits in the drum and is designed to be loaded with the Jobo 70mm loader. It holds a full load (15ft / 5M) of film.
• 3025 70mm Loader Base: This is the magic that brings everything together. The reel mounts to it, along with a cassette spool. It takes only seconds to spool, and a few more seconds to load the entire roll with the supplied crank.

Using this system with a Jobo processor is the easiest possible way to develop 70mm film. Loading a full 15ft load is easier than loading a single roll of 120 film (that's at least 5X less work), and it is developed all at once as easy as any other Jobo Expert Drum. It is very easy to develop BW or color with this system. A single load requires only 750 mL of chemicals.

The main drawback is that this system is extremely rare. They come up for sale only very rarely, and can be quite expensive. Plus, you have to own a mid to high level Jobo processor to use this. So this is not for everyone.

Mercury Works developed a tool to make loading a the Jobo 5M reel much easier: a simple punch. When the end of the film is seated in the punch tray, the resulting hole will be optimized for the Jobo system. This can be done in the light or in the dark.

This is a far more affordable option. It functions just like a standard daylight tank, but much larger. A stainless steel reel is hand-loaded from the center out (this is not a friction-load system like Paterson or Jobo) and placed in the plastic tank. The lid fits tightly on it, and all developing steps can be accomplished in light. The tank lid possesses a light blocking port to pour chemicals in and out. Agitation is via inversion.

This is an effective system for developing 70mm. Its chief disadvantage is the large volume of chemicals required (2L), and the greater amount of time that it can take to fully transfer them. I wouldn't recommend this system for color processing, but it works fine for BW. It works best if you use a dilute developer, which will be more tolerant of imperfect timing and more economical given the large volume the tank holds.

This system also requires some practice and patience when loading the reel. It’s a big one!

This is similar to the Kindermann system except that the stainless steel tank does not have a daylight port. Thus all transfer of chemicals must be accomplished in darkness. However, chemical transfer is much faster: you can dump in or out a large volume very quickly.

Hewes in the UK still manufacturers, when requested as a special order, long roll stainless steel 70mm reels. These reels fit perfectly inside a 3L pressure cooking pot for easy darkroom development.

For this to work, you must first modify the pot's lid to be water tight in order to enable inversion.