DBI and Fogging

[G Benaim]

Hi All,

Just started doing DBI after reading Michael Smith's article, and have had some fogging. Most films turn out fine, but some do fog. I use FP-4 and HP-5 in 4x5, dev'd in Rodinal, and a 15w red light which I turn on 75% into full normal development. It's about 3 ft from the film, sometimes more. I sometimes have to look several times during the course of development, because I can't always see clearly the highlights. I read, however, in the AZO forum that it's hard to fog film even after several exposures to the light. Is this true only for pyro, or is it also true for other devs? Would the color of the light have anything to do w it, esp. w how easy it is to see the effects and therefore causing longer evaluation times? I usually look for 3-4 secs at a time. Would a green light make that much of a difference?
On another topic, emulsion up or down to prevent scratches? Thanks for the help,

GB

[Michael Gudzinowicz]

The article: http://www.michaelandpaula.com/mp/devinsp.html

A red safelight definitely will fog less exposed areas of film regardless of development time. I use a few seconds of exposure for Sabattier film reversal after development in Dektol.

The green safelight used for development by inspection is very dim and the wavelength was chosen to correspond to the eye's region of maximum sensitivity. I'd suggest using the recommended light, distance and time, and running tests.

For instance, carefully expose a few sheets of film, and develop one perfectly by time and temperature. Develop another for 50% or 75% of that time, and 100% of that time, placing them in an acid stop bath. Examine the two stopped and unfixed negatives under the green light for a second at 3 or 4 feet distance so you'll know what the endpoint looks like. Develop the 50% or 75% negative for the remaining 50% or 25% of the time, stop, and fix that negative and the 100% negative that's been in the stop bath. Compare the unexposed/shadow areas for fogging.

EMULSION DOWN when shuffling!

[Ken Lee]

You might find it helpful to use an infra red viewing device, which lets you see everything all the time. It's like working in a fully lit room. For DBI, it's the bee's knees.

[Geert]

EMULSION DOWN when shuffling!

Does this only apply to DBI but also to "classic" tray developing?

I use a slosher tray, so emulsion up is the key.

Thanks for some more info on this issue.

[Michael Kadillak]

The article: http://www.michaelandpaula.com/mp/devinsp.html

A red safelight definitely will fog less exposed areas of film regardless of development time. I use a few seconds of exposure for Sabattier film reversal after development in Dektol.

The green safelight used for development by inspection is very dim and the wavelength was chosen to correspond to the eye's region of maximum sensitivity. I'd suggest using the recommended light, distance and time, and running tests.

For instance, carefully expose a few sheets of film, and develop one perfectly by time and temperature. Develop another for 50% or 75% of that time, and 100% of that time, placing them in an acid stop bath. Examine the two stopped and unfixed negatives under the green light for a second at 3 or 4 feet distance so you'll know what the endpoint looks like. Develop the 50% or 75% negative for the remaining 50% or 25% of the time, stop, and fix that negative and the 100% negative that's been in the stop bath. Compare the unexposed/shadow areas for fogging.

EMULSION DOWN when shuffling!

I was taught by Michael and Paula to tray develop negatives emulsion side UP during the Development By Inspection segment of their workshop. Below is a post from the Azo forum articulating the rational for this recommendation.

Michael A. Smith Posted at: 5:04:25 AM PT, 12/22/2002

We develop face up. The rationale for that is that no air bubbles get trapped underneath, but I have never hear of anyone who developed face down getting air bubbles. In addition, we feel there is less scratching by developing face up--the emulsion side of the negative does not touch the bottom of the tray.

Bottom line: I do not think it matters. Do it the way you have always done it. If you ever have a problem, then switch. Not before.