Divided Development – An Introduction

Divided development is the use of two baths – “A” contains ‘developer’ and “B” contains an ‘accelerator’ – to develop film. This has benefits and drawbacks:

Advantages

• Development times are insensitive to temperature (but see below).
• Times are also constant across all (B&W) films – 25asa film can be developed alongside 3200asa film.
• Both baths are reused many times – cost is extremely low particularly if made up from raw chemicals.
• Extremes of brightness range can be captured – developer is soaked into the film from bath A and when bath B is added exhaused developer is not be replenished as would be the case with a one-bath developer with agitation.
• Useful for 35mm film where both high and low contrast images may exist on the same film

Disadvantages

• The development is necessarily low contrast – if the image is low contrast then a very high contrast printing paper or substantial adjustment to the contrast curve is needed in post.
• Subtlety of contrast variation may be lost
• If made from raw chemicals then in a cold darkroom some crystallisation in A or B may occur leading to spotting on the negatives (see the featured image).

Variants and Method

For a much more in-depth explanation see this article by Jacques Kevers and “The Darkroom Cookbook” by Steve Anchell.

An infinite range of variants exist broadly going under the names DK-20, Stoeckler, Thornton,  Divided D23, Divided D76, D2D. In each of these the quantity of chemicals can be varied – so the names can start to overlap.

I have used a version of D23 in the past and for this article I used a particularly simple developer to make up which I know as Stoeckler. Bath A comprises 5g Metol and 80-100g Sodium Sulphite in 1ltr of water, and Bath B is 10g Borax in 1ltr of water. (Dissolve the chemicals in water around 40-50 degC, the Metol first with a pinch of sulphite, then add the rest of the sulphite.) Development was 3 minutes in A, then 3 minutes in B (without any water rinse in between!), agitation continuous for 15 seconds then once every 15 seconds. This is followed by the stop bath then fix and wash as usual.

Having a cold darkroom the main problem I have found with both developers that I have made up is crystallisation of some of the chemicals. Filtering is not a good option since this changes the concentration of the chemical in the solution – the recommended approach is to gently warm both baths until everything has dissolved. Unfortunately this negates one of the main advantages of the method (its insensitivity to temperature).

Commercially made up divided developers are available from Nik and Trick: Thornton’s, and Diafine (as used by Ibraar Hussain). They make two versions of Thornton’s, formulae are available online (thanks to Nik and Trick for the info). If anyone knows what the make-up of Bellini’s Diafine is please let me know! Also please let me know if you have any crystallisation or spotting problems from either of these commercial versions.

Results

I decided to shoot a variety of scenes ranging from very high contrast conte-jour to very low contrast scenes. I was using a Leica MP with a Zeiss Sonnar lens, FP4 film and scanned with a Sony A7Riii, Sigma 105mm macro lens, and processed in RawTherapee. Processing with one exception (noted below) was minor cropping and straightening, and setting black and white points with a straight line contrast curve in between. Necessarily on low contrast scenes the image histogram was a blip on the horizontal scale and the contrast curve ends up being near vertical – so the final image has been extracted from a tiny contrast section of the negative emulsion.

Conclusions

If you have a warm darkroom, shoot a mix of film speeds or have very high contrast scenes captured on the film then divided development is well worth considering (as is Pyro or stand development). For general use there are better alternatives in my opinion although (apart from the spotting) I am pleased with several of the images.

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