Tray processing, John Sexton technique : LUSENET : Large format photography : One Thread

Hello fellow light catchers, I read a post awhile back where John Sexton uses a small plexiglass with pegs screwed onto it to hold the sheet film in place. You then drop the plate in the trays of chemicals and never come in contact with film. Does anyone have any more information on this type of device or where to purchase it. Thanks in advance

-- Belden L. Fodran (, January 25, 2000


I've heard them referred to as "slosh trays" and have been using a couple of them for the past three years. They work great. Only thing is you have to make them yourself. This is not too difficult. The first thing you need is a set of 8x10 trays that will be big enough to hold the plastic panels, but not so big as to require a lot of developer. I found that some old Vivitar trays work great. What you want to do is draw out a plan view of the panel using 4 sheets of 4x5 film as a template. You need to center two dowels on each side of the film and leave about an 1/8" clearance so film won't bind. The inside edges of the four sheets can share dowels to keep size down and reduce the number of dowels needed. You can purchase some 1/4" plexi from a local plastics supply house. They will trim to size for a nominal charge. At that same place, you'll be able to buy a 1/4" plastic drill bit which you'll use to drill the holes for the dowels. Oh, also buy a length of 1/4" diameter plexi rod and a tube of plexi cement. The dowels need to be about 1-1/2" long. Cut with a hack saw and finish ends with a belt sander. Use short bursts of contact with sander or you'll melt the rod. If you have a drill press, use it! This will keep the holes perpendicular to the panel so they'll look nice and straight. Some people drill some additional holes under the film area to allow better circulation of chemistry. I haven't done this, but it seems to do a very even job regardless. Good luck and wear those eyeshields!

-- Robert A. Zeichner (, January 25, 2000.

Yah meen Dr. John stopped using a JOBO??? My god! All my photographic idols are falling from the pure techno-faith!!!

-- Sean yates (, January 25, 2000.

Can someone post a sketch or picture of the this device? It sounds like a great idea. Thanks.

-- Chris Hawkins (, January 25, 2000.

I don't think you can post pics here, can you? I think I've got that drawing I saved from a magazine article. Send me an e-mail and I'll scan it.

-- Alec (, January 25, 2000.

The Mar/Apr 1990 issue of Darkroom & Creative Camera Techniques (now Photo Techniques) has an article by Howard Bond "Testing for Even Film Developement" which show photos of several different veriations of these devices.

-- John Hoenstine (, January 26, 2000.

No, John Sexton still uses the Jobo as far as I know, as does Howard Bond. That is a wonderful system, just one I can't afford, nor have the space for.

-- Robert A. Zeichner (, January 26, 2000.


I made something similar. Not much to it. I skipped a step (the sheet of plexiglass), and just glued some thin strips of plastic directly onto the interior bottom of an 11x14 tray. I spaced these strips accordingly for 4x5 sheet film, and cut shallow grooves into the strips so I could easily slip the edges of the sheets into them.

The individual sheets are held in place by one grooved plastic strip on either side, suspended slightly above the bottom of the tray. I use three strips, positioned to hold four sheets of 4x5 film in the tray. I'm sure you can form a mental picture without too much trouble.

Its real advantage is that you can process several sheets of 4x5 film simultaneously without the sheets coming into contact with one another during development/agitation, thereby totally eliminating scratching of the emulsions during development.

Scratching the emulsion during development has to be the most frustrating part of LF development! I'm sure that all those LFers that have attempted that old timer's trick of developing a bunch of sheets at the same time, using the so-called interleaving method, have discovered that this constant shuffling of the films during development, when the emulsions are at their most delicate, invariably results in lots of scratches on the emulsion.

I could never understand how these legendary, grizzled LF sages could handle a bunch of sheets at the same time, much less keep track of each sheet's individual development time in total darkness. The scratching occurs when the very sharp edges of the other films inevitably comeinto contact with the other films during the shuffling process.

The act of smiply handling a single sheet of film with your hands will not scratch it. The device in question eliminates this film corner to emulsion contact.

Good luck, Sergio.

-- Sergio Ortega (s,, January 26, 2000.

Carlos R. Herrera kindly forwarded on a URL where the construction on the panels is detailed.

Thanks to Carlos!

-- Chris Hawkins (, January 28, 2000.

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