The problem with evaluating the negative based on the emulsion side is that you are seeing reflected light only. So you are seeing only the surface of the emulsion, the rest of the emulsion may be undeveloped. Stopping development at this point will lead to thin negatives. This is why the base side is used since if you see a satisfactory image it means that the entire emulsion has been developed. Thus the warning to inspect the base side of the film. Every discussion of the technique that I have read always mentions doing this.
The idea that the oxidation products of the developer act as a desensitizer is very old. If the effect ever existed it would be dependent on the developing agent(s) used. I seriously doubt that the developing agents used now would have the same effect. The oxidation products of phenolic developing agents like pyrogallol are vastly different from those of a developer like Xtol.
I'm just curious. Thanks!
I'm just curious about what is actually happening. I would LOVE to get some nice IR googles, glass trays with an IR light source underneath them some day. :cool:
It is likely the tanning process which helps slightly. In any case ABC (Kodak D-1) doesn't produce such heavy stain unless you alter the dilution for less sulfite. Kodak later came up with formulas which were designed for more imagewise staining.
I'll also throw in my white elephant for the fun of it: why anyone would bother in this day and age with DBI versus time/temperature control is beyond me. In the days of Weston it made some more sense because light meters were primitive, and materials were subject to more variability (film speeds, developer activity, etc.). At this point, what value can it possibly add?
I find that by keeping things as simple as possible, I reach higher and farther with my photography. But it's still interesting to learn, even about things I will never use. It helps paint a bigger picture, and better understand the things I do use, and it throws perspective on those processes that I'm tempted to try, as well as their actual utility.
And cool factor.
Cool factor I'll agree with - but only if you have the goggles.
True desensitizing dyes greatly reduce an emulsions sensitivity to light . Such dyes as scarlet N and pinakryptol yellow allow a much brighter safelight illumination. So if oxidation products do act as desensitizers their effect is rather small by comparison. The level of illumination used for this development technique is probably too low to have any visible effect on the film provided that exposure is short.