Cross Processing

Cross processing, (a.k.a. X-Pro, xpro etc.), is a technique of developing one type of film in another's chemicals. The most common form of cross processing is taking colour slide film (E6) and developing it in colour negative (C41) chemicals.

So why would you want to cross process? It usually results in wild and unpredictable results; colour shifts, high contrast, and other such loveliness. It can add a further level of interest to your images when it compliments your subject matter.

Got any tips?

Unfortunately, or fortunately as the case may be, cross processing is a unique experience, so what works for me may not work the same for you. You are going to have to do some experimenting, but here are some tips for things to try:

  • Try some different types of film, and compare the characteristics of each.
  • Try pushing or pulling your film.
  • Try over or under exposing your film.
  • Combine X-Pro with other techniques: multi-exposures, 35mm, filters and flashes.
  • Get a load of expired film to use in your X-Pro experiments: expired film tends to be much cheaper than in date film.

Cross processing works best on bright sunny days, with plenty of light. The best subjects seem to be once with plenty of colour, although my favourite subject for cross processing are neon signs. They really seem to pop out of the image when crossed! Cross processing film shot on a dull day can be advantageous, as it can get help to improve the contrast.

Pushing and pulling film

Flickr member EATENalive recently explained to me how pushing and pulling affects cross processed film. You can read the full thread, or keep reading for my condensed version.

Pushing film involves deliberately underexposing your image, then asking your lab to push (over-develop) the film 1 or 2 stops to compensate. This results in higher contrast than you would get shooting and developing a film at its rated speed.

Pulling film involves deliberately overexposing your image, then asking your lab to pull (under-develop) the film 1 or 2 stops to compensate. This results in lower contrast than you would get shooting and developing a film at its rated speed.

Bear in mind that cross processing already increases contrast, so you may have to consider pulling the film to compensate. Here are a couple of real world examples:

  • Its sunny outside, and what you are shooting is very high contrast. You shoot 200 ISO film as if it were 100 ISO. You then drop your film off and ask the lab to cross process it, and to pull 1 stop. This results in your pictures having more normal contrast while still leaving room for colour casts.
  • You are shooting something indoors, and there is low contrast in your scene. You shoot your 400 ISO film as if it were 800 ISO. You subsequently drop your film off at the lab and ask them to cross process it, and to push 1 stop. This results in your pictures have higher contrast than they would have done normally.

Of course this is all easier said than done with a Holga! Still, it's interesting to know, and I'd like to thank EATENalive for explaining it in terms I could understand.

Types of cross processing

  • E6-C41: taking slide (colour reversal) film, and processing it in colour negative chemicals. This is the most common type of cross processing. It usually results in increased contrast with strong colour casts.
  • C41-E6: taking colour negative film and developing in slide chemicals. This usually results in muted pastel colours with very little contrast. As a result you may want to ask your lab to push 2 or 3 stops to increase the contrast.
  • E6/C41-B&W: taking colour reversal or negative film and processing as black and white. This results in a black and white negative. As colour film is usually more expensive than B&W, you may want to only use this technique if you are out shooting colour and decide you'd rather have B&W.