Where do the sensitizers go?

Hello all,

 

First of all let me start off by thanking all of the regular contributors to this forum. I've learned a tremendous amount by reading the posts here.

 

My question concerns the makeup of B&W film. I know that the natural sensitivity of silver halides is toward the UV and blue end of the spectrum, and that B&W films incorporate sensitizers to give panchromatic character to the emulsion (make it respond to the red end of the visible spectrum). Presumably extended-red (eg. Ilford SFX) and infrared (HIE, Konica IR, etc.) have more and/or different sensitizers. The question is -- What happens to these sensitizers during development? Are they chemically reduced by the developer, or washed away in any way? Or do they remain in the emulsion forever?

 

Thanks in advance!

Reminds me of that old Rita Rudner routine about how paste is made from flour and water. So, when we bake a cake, where does the paste go?

I don't know completly what happens to all of it, but a good deal of the sensitizers come out during processing. There is usually a small amount left, which can sometimes give the film a slight color cast (the sensitizers are mostly dyes), but these will usually fade with exposure to light.

 

David Carper

 

ILFORD Technical Service

The sensitizing dyes are washed out during processing.

 

Michael D. D'Avignon

 

www.fujifilm.com

 

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