How is a blind character working at film developer lab?

Reba works with highly sensitive infrared film.

REBA: The 1000 C Infrared Sensitive Film must be handled in total darkness. I keep the samples straight by touch code.

^Script

The novel explains further.

...she outlined the mechanics of the development—chemicals, temperature and time, and storage procedures before and after filming.

Infrared-sensitive film must be handled in total darkness. She had done all the dark room work, keeping the many samples straight by touch code and keeping a running record in the dark

^{Red Dragon - Thomas Harris}

The point here is that she is working with infra-red film which is sensitive to any light therefore anyone developing it needs to work in total darkness so being blind is no disadvantage plus someone who is blind is actually much more used to working without being able to see so a blind person is actually at an advantage in this job.

Note also that the job is processing the negatives which is pretty much a purely technical operation as opposed to actually printing copies onto photographic paper which is a bit of a different thing.

After many years working in the darkroom, mostly processing negatives, I noticed something.

Not only do I do this in complete darkness with no issues. I realised that, probably already for several years, I even close my eyes. This way I "see" the film better :-)

And the other trick btw, to find the emulsion side is, to carefully take one corner between your - dry - lips.

The side that sticks is the emulsion.

You misunderstand the wet process. The development of film is prepared in complete darkness - you have to take the film out of light-tight cassette and put it in light-tight canister - and it is done in light-tight canisters. There is absolutely no way how to adjust the process according to actual state of the film.

You put the film in, close it, pour one chemical in , wait, pour chemical out, pour another in etc. Finally you get the result.

The only thing that blind person cannot do is the final assessment of the result. And developed film can wait a long time for someone to see it. During other steps, blind people have significant advantage - they do not need any light, their other senses are boosted and they do not need hand-eye coordination to do anything.

The more the film is sensitive, the fewer light is allowed to help the operator to coordinate their hands. Blind people do not need any light.

The only steps you actually need to see anything is evaluation of the negative whether it was processed right then you can start developing the positive - the actual image. Here you have to focus the projection and you can alter the brightness etc.