Cross Processing: Weird Science

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We have become used to seeing distorted colour and even early television programmes, such as Top of the Pops and Dr Who, show-cased what was possible by turning all the dials to ten to see what would happen. The music industry has been a real driving force in visual experiments and although most effects can be achieved via software, there is a lot to be said for the old fashioned analogue approach, using film. The quality of images produced by colour films are extraordinarily good but they rely on a carefully designed and managed system to guarantee accurate results. So why not through out the rule-book and see what happens?

Cross Processing
Experimenters in weird colour often request 'cross-processing' , which is trade slang for putting a film through the wrong processing chemicals. Before going further it is probably useful to explain a few of the trade-slang words you may have heard.

Colour Negative film requires a particular set of chemicals called C41, which were invented by Kodak. These films that are distinctive by having an in-built orange cast to the film base ( the colour bias helps in the subsequent printing stage in making colour photographs). Other manufacturers produced their own versions of the film and chemistry: Fuji has CN16; Agfa had AP70; Konica had CNK-4 but they were all compatible with the original C41.
C41 has become a slang term that describes the film, the chemistry and even the photographs ( sometimes called C-type prints) . It is a sloppy description that could lead to confusion if you intend to experiment with different processes.

Transparency film also has its equivalents and slang terms, so transparency film = slide film = E6 film and was manufactured by Kodak as Ektachrome; by Fuji as Fujichrome and Agfa as Agfachrome. Kodak invented the process and the other manufacturers adopted the same standard but produced their own brand of chemistry. Fuji has CR-56; Agfa had AP44 but even today Fuji quotes both their own and Kodak process names on the packaging.

film bar code

The final piece of slang is cross-processing, which describes both putting colour negative film through E6 chemistry as well as putting transparency film through C41 chemistry! Confused?! Most professional laboratories are able to cross-process limited amounts of film at a time but you need to be quite explicit with your request because they go to great lengths to ensure it doesn't normally happen. We are happy to cross process but please use BIG LETTERS in your instructions so that can be no misunderstanding.

Below are some experiments we have made to illustrate the kind of effects that can be achieved. These are just a starting point because we have had clients who have distressed film in advance to see what would happen: when I first bought a microwave oven I tried cooking some film to see what would happen... don't bother - it wasn't very exciting!

cross-process sample



Standard slide film and E6 process
Imperial gardens in Cheltenham provides a suitably colourful scene for some colour experiments. This was transparency film, Fujichrome 400asa, developed normally through E6 chemistry. The strong colour saturation and detail of this type of film made it very suitable for slide projection or subsequent reproduction in magazines etc.


cross-process sample



Colour Negative through E6 process
Colour negative film developed through E6 chemistry. The colours are flat and the orange hue is a feature of most colour negative films. The orange colour 'mask' is permanent and was designed to help the printing process when paper is exposed through-the-lens


cross-process sample



Colour Negative film and C41 process
Colour negative film, developed normally. This is the most common film type used and allows for very life-like colours to be printed onto photographic paper. Provided the initial C41 process is correct the colour is adjusted as the final print is made.


cross-process sample



Transparency film through C41 process
Slide films such as Ektachrome or Fujichrome can be cross-processed through C41 chemicals. The resulting prints or scans generally have very saturated, contrasty colours: skin tones look particularly strange and if the processing time is extended through 'push-processing' then the effect can be further exaggerated.


cross-process sample



Red Col Neg film through Col Neg process
A fairly recent innovation by Lomography has been to sell film that is literally back-to-front: the image is exposed through the orange mask, which is present on the back surface of colour negative films but here it has the effect of looking through it, producing strong reddish images. You don't have to use Lomo Red film for this - we used some old Boots film, which we rewound into the cassette back to front.


cross-process sample



Red Col Neg film through E6 process
The same back-to-front film, as above but cross-processed through E6 to see what would happen... it's bit boring really but worth a try. The colours just looked very flat and grey but it might suit a less 'sunny' subject.


All the tests were shot with a Nikon F3 using a variety of films. Each sample was scanned using our Noritsu equipment.

When you cross-process film you can never be quite sure how things will turn out, but that is the fun of it. At The Darkroom UK Ltd we are always keen to help out with experiments but, since we take great care in managing accurate processing, we may not be able to fulfil every request.

Alistair Baird
The Darkroom UK Ltd
01242 239031