Reflective clear stain on 35mm Negatives

[dbr73]

Hello,

I have a weird stain on some of my film with that is clear and reflective. It looks elevated on the surface. I’ve already tried washing the film and cleaning, does anyone know what it is from or how it can be fixed?

Edited November 7, 2022 by dbr73

[Alan Marcus]

The light-sensitive coat called an emulsion consists of salts of silver imbedded in purified gelatin. The structure of the gelatin binder, under the microscope, resembles spaghetti strands. This noodle-like structure swells as the waters of the developer are absorbed. Wet gelatin has open pores; this allows the fluids of the process to enter, percolate about, and exit with agitation.  

As the process proceeds, we wash the film and/or use a rinse agent to rid the emulsion of the chemicals of the process. Last, we use a wetting agent that reduces the likelihood of the rinse water from beading up leaving fluid standing on the gelatin’s surface.

Next, we air-dry the film. As the film dries, the gelatin binder shrinks back to its original thickness. Should the final wetting agent (PhotoFlow or equivalent) be omitted, we must squeegee the film to remove beaded or standing water.

Should beading of standing water remain on the surface, it interferes with the gelatin shrinking process. The result is a higher surround area that looks like a stain, called a water mark.

Water marks are hard to remove. Gelatin swells in an alkaline solution. Try soaking the film in the developer. It is an alkaline solution, and this process will soften the gelatin. Don’t worry, fixed film will not re-develop, so no harm except the film is soft and easy to scratch. Soak for 5 minutes and then wash in running water for 10 minutes. Soak for 30 seconds in a rinse agent and hang up and allow to air dry.

Maybe a 25% chance of improvement.

An old trick -- If you print on photo paper using an enlarger, some have a negative carrier that allows printing wet negatives. If this is the case, print wet using the enlarger, likely the water mark will not be seen.

Edited November 7, 2022 by alan_marcus2