Orbital Processor Film Modification

The Orbital Processor is a paper processing unit produced by Paterson in the early eighties. It’s designed to allow the processing of colour photographic paper with the room lights on, and can handle 1 sheet of 8×10, 2 sheets of 5×7 or 4 sheets of 5×4.

A friend and fellow large format dabbler, Ian McInnes, suggested that it might be possible to use it to process 5×4 (or larger) sheet film, and so bought one. Initial tests revealed that although it did work quite well, the film tends to stick to the bottom of the unit, with the result that the anti-halation backing doesn’t wash off completely during processing. It does seem to clean off during subsequent washing, but this isn’t really ideal. After buying one myself and trying it out it occurred to me that what was needed was a way to allow the processing solutions to get under the film during agitation.

With the lid off you can see the separator pegs used to keep the 4 sheets of paper (or in this case, film) apart during processing. Two of these pegs are removed for 5×7 processing, and all of them for 8×10. If you’re buying an second hand Orbital, make sure it has at least 4 pegs as these are often lost, and it’s not much use without them.

My solution to the film sticking problem was to stick a couple of little self-adhesive feet to the middle of the tray. I found a couple left from the pack that I bought when one of the original feet fell off of my iBook. I had to use both of them to cover enough area to catch all four sheets of film.

When a sheet of film is placed in the tray, the corner is held up slightly. From the tests done so far, this does indeed allow the processing chemistry to get under the sheet of film and wash off the anti-halation backing, and so far they haven’t fallen off. This arrangement should be fine for 5×4 and 5×7, but wouldn’t be great for 8×10.

If you try this, or have a better solution, please let me know what results you get.

DaveMc, May 2007.