markjwyatt
No longer a newbie, moving up!
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I posted some of this on another forum, and will try and make it more concise here.
Manufacturing film requires substantial capital investment and commitment. Though it may be possible to scale down using simpler processes, this will end up making film very expensive. Today film (and print paper, etc.) is produced on huge coating lines (illustrated is a typical coating line, likely NOT for film).
The heart of the system is called slide curtain coating. The layers of emulsion need to be coated onto the cellulose base in a manufacturing operation. Kodak, Fuji, Polaroid, and others were experts in operating this type of equipment.
The layers are fed into the rear in pipes then distribute across the web width internally (not sure what widths the photo manufacturers used, maybe 1 m to 2 m), then they came out the exit slots where they stacked without mixing, then slid down the slide, and fell as a curtain to the cellulose or other substrate below, which was moving (not sure what speed, maybe 500-1000 meters/minute). I suppose some operations could coat and dry a single layer at a time, but my understanding is the more advanced companies coated all layers at once. Slide dies can build up many layers. Note curtain coating does not work at low speeds.
I am very familiar with the die coating process (mainly slot and curtain dies), but not in the photographic industry.
Fuji patent: Patent US6607786 - Method of curtain coating
Here is an article that shows some images of a Kodak photographic paper coating line in London (Harrow). They do not show any details of the coating operation, which is the heart of the line. Generally, coating companies keep that type of information fairly proprietary.
Kodak Factory, Harrow, London
Here is the same for an Ilford line ( looks like ~1 m line). Again, they do not show the actual coating operation.
The tech of photo paper: how it's made | TechRadar
Manufacturing film requires substantial capital investment and commitment. Though it may be possible to scale down using simpler processes, this will end up making film very expensive. Today film (and print paper, etc.) is produced on huge coating lines (illustrated is a typical coating line, likely NOT for film).
The heart of the system is called slide curtain coating. The layers of emulsion need to be coated onto the cellulose base in a manufacturing operation. Kodak, Fuji, Polaroid, and others were experts in operating this type of equipment.
The layers are fed into the rear in pipes then distribute across the web width internally (not sure what widths the photo manufacturers used, maybe 1 m to 2 m), then they came out the exit slots where they stacked without mixing, then slid down the slide, and fell as a curtain to the cellulose or other substrate below, which was moving (not sure what speed, maybe 500-1000 meters/minute). I suppose some operations could coat and dry a single layer at a time, but my understanding is the more advanced companies coated all layers at once. Slide dies can build up many layers. Note curtain coating does not work at low speeds.
I am very familiar with the die coating process (mainly slot and curtain dies), but not in the photographic industry.
Fuji patent: Patent US6607786 - Method of curtain coating
Here is an article that shows some images of a Kodak photographic paper coating line in London (Harrow). They do not show any details of the coating operation, which is the heart of the line. Generally, coating companies keep that type of information fairly proprietary.
Kodak Factory, Harrow, London
Here is the same for an Ilford line ( looks like ~1 m line). Again, they do not show the actual coating operation.
The tech of photo paper: how it's made | TechRadar
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