Is total darkness required for tray developing film?

[Justin K]

I have a "darkroom" that's really just a very dark basement area; definitely not 100% light-tight, however. I expose and develop BW prints in this space all the time without any fogging or other issues. Now I'm interested in trying tray development of BW negs ranging from 4x5 to 8x10. I have years of experience developing film in a Jobo and standalone tanks, but sometimes the Jobo is overkill for just 1-2 negs, for instance.

My questions about tray development:

1. How dark is "dark enough" to tray develop film safely? Do I need a 100% light-tight darkroom and total darkness?
2. If I do need total darkness, how then do people manage to "develop by inspection" (as I've seen some others mention in various forum posts about tray development) using tray development?

Thanks very much for any tips and advice!

[Pere Casals]

It depends on the film, orthochromatic type film can be developed under red safe light...

But for tray development just use a cheap paper safe. When development done just close lights to move sheets to a regular tray with the stop bath, after some 15s you can open lights and also fix with lights open.

You also can also use a toy ir device:


Or an expensive IR night vision device, if your film is not for IR...

[Alan9940]

Well, I guess the answer really comes down to: How dark is dark? How long will the film be exposed to whatever amount of light is present? Will your body somewhat shield the film from the direction of the light? I guess the easiest way to answer your own question is to develop an unexposed sheet of film, stop, fix, etc, then see if any density shows up on the film. If no, you should be good; if yes, you're not.

Development by inspection is not done with the light on. The film is developed in total darkness for roughly 75-80% of the expected total development time, then a very dim safelight is turned on briefly to check the high values. Plus, most folks who do DBI use staining type developers which hardens the emulsion as the film is developed, thereby enabling the film to somewhat resist exposure to light.

[Bob Salomon]

Well, I guess the answer really comes down to: How dark is dark? How long will the film be exposed to whatever amount of light is present? Will your body somewhat shield the film from the direction of the light? I guess the easiest way to answer your own question is to develop an unexposed sheet of film, stop, fix, etc, then see if any density shows up on the film. If no, you should be good; if yes, you're not.

Development by inspection is not done with the light on. The film is developed in total darkness for roughly 75-80% of the expected total development time, then a very dim safelight is turned on briefly to check the high values. Plus, most folks who do DBI use staining type developers which hardens the emulsion as the film is developed, thereby enabling the film to somewhat resist exposure to light.

Best test is to place a coin, in total darkness on a piece of unexposed film, then put the film where you will process and leave it, with the coin on it, for the period of time it will be developed, then develop it and see if the area that had been covered with the coin has a different density. If so you need to find a way to darken that area, or process in your bathroom or use a daylight tank like the CombiPlan.

[Ken Lee]

I didn't see Bob's post (the coin is an excellent idea), but here's a variation:

Cut a sheet of film into some pieces (or use several sheets) and leave them face up on your table in that room for 5, 10, 20, 40 minutes or according to whatever scale you like. Place a coin on each piece.

Develop them all together in total darkness. Fog may become apparent after some length of exposure. If it's between 20 and 40 for example, you can interpolate or test again with closer intervals. This all varies with film ISO, time of day etc.

With my methods, I consider 1 minute for film handling, 2 for pre-soak, 10 for normal development, 1 for stop-bath, 2 in fixer before the film is safe to expose to normal light: 16 minutes total. I would want to be able to leave the film in the room for at least that long, maybe double just to be safe, especially since expanded development takes longer.

[koraks]

Cut a sheet in half. Develop one half in a for you typical way in the "dark" area. Then fix and wash as usual. Fix and wash (not develop) the other half sheet. Compare them when they are dry. The developed half should have only marginally more density than the undeveloped sheet. This works best with a non-staining developer and fresh film since both general stain and fog from age will create base density.
As to the question if dark is dark enough: if you are in the dark room for 10 minutes so that your eye are really accustomed to the dark, if you see any contours or can see the outline of your hand in front of your face, it's not dark enough (but it may still be good enough for your own taste).

[Doremus Scudder]

You can always restrict your tray developing to times when the light leakage is at a minimum, e.g., at night. I read that Brett Weston used to develop film and print at night with his darkroom window swung wide open. The moonless night sky wasn't bright enough to make a difference.

If, after testing as outlined above, you find you have too much light to tray develop, look into acquiring (or building yourself) a set of BTZS tubes. These allow tray-type developing and protect from ambient light.

Best,

Doremus

[Bob Salomon]

You can always restrict your tray developing to times when the light leakage is at a minimum, e.g., at night. I read that Brett Weston used to develop film and print at night with his darkroom window swung wide open. The moonless night sky wasn't bright enough to make a difference.

If, after testing as outlined above, you find you have too much light to tray develop, look into acquiring (or building yourself) a set of BTZS tubes. These allow tray-type developing and protect from ambient light.

Best,

Doremus

That open window procedure would not be best with the speed of today’s films and would not lead to the cleanest work area!

[Pere Casals]

Kodak is kind enough to provide sensitometric datasheets with absolute scales, this tells how dark.



So 0.003 Lux for a few seconds would start building fog.

We cannot do tray processing with some ambient light during all development !!!

In development by inspection we open for a few seconds the dim light at the end of the development, in that case that exposure to light is not much harmful because to have an effect the newly exposed grains have to wait the induction time to start developing, and when that development start building serious density a couple of minutes have passed, and we perhaps by then we have finished our development by inspection.

... but, as graph shows, if we throw to film some 0.1 Lux·Second during the first two minutes (lirf apart) then we add 1.0D fog to the negative.

...and 0.1 Lux.second in 2 minutes are less than 0.0008 LUX ambient light.

So even with ISO 100 film it is not feasible to do tray developing with some ambient light, just place the sheet in a paper safe and open lights, or use a night vision device.

[Drew Wiley]

It takes very little light pollution to fog the shadows in films with long straight line sensitivity way down into the shadows like TMax 100. Make that TMax 400 and you multiply the risk. Even the illuminated hands or LED's of a darkroom timer can cause havoc. I place the timer below the sink, where the film trays are incapable of "seeing" it. Once someone has pinned down personal exposure and development technique, and learned how easy it is to keep dev temperature stable in a water jacket around the tray, why on earth is dev by inspection even necessary? I know this is how some people have always done it; but why on earth anyone would aspire to this approach today mystifies me.