Last year, Destin Sandlin of the YouTube channel Smarter Every Day showed the science behind film development. Sandlin explained how photographic film is constructed, exposed, and developed. Sandlin discussed the film's chemical structure and then shot some film.

Sandlin loves film. It has a special, unique quality that is tough, if not impossible, for digital cameras to match. He gets his film developed at Indie Film Lab in Montgomery, AL. You can see the lab at work in the video above.

Sandlin wasn't satisfied explaining how film works, so he kicked off a three-part Kodak factory tour. Sandlin released the first part of his tour in March. In that video, seen again below, Sandlin discussed the first of three primary manufacturing stages of film-making, the film base itself.

Sandlin's first tour at Kodak's factory in Rochester, NY, was led by Matt Stoffel, a third generation 'Kodaker.' Kodak was founded in 1888 when George Eastman created the first Kodak camera. The Kodak building Sandlin visited was built in 1891.

Sandlin just released the second part of his three-part Kodak tour, focusing on how Kodak turns the film support and base we saw made in the first part of the tour into light-sensitive material.

Different kinds of film use different coatings. The variations in emulsion result in a wide range of tones, grains, and overall look of your images. In Sandlin's tour, he sees how Kodak applies the light-sensitive coating to Ektar 100 film. Ektar 100 is a color film known for its extremely fine grain appearance.

It may seem obvious once you think about it, but it's amazing to consider that the factory process for applying a light-sensitive coating to a film base must be done in complete darkness. After all, exposing the emulsion to light while applying it to the film will ruin it. The process must be performed in pitch-black conditions with minimal human intervention. Whereas people are heavily involved in different steps in the film base production process, turning that film support into a usable film requires a different approach.

The coating must be applied wet, too, which makes it very fragile. It also must be dried without being damaged. The point is that there are a lot of potential problems along the way. Kodak provided Sandlin with different engineering drawings showing its film coating facility, which he and his team then turned into 3D models. It's an incredibly intricate, complex process done in total darkness, making it even more impressive. 'Once you understand how this facility works, it makes shooting with the film even that much more rewarding.'

Each layer of light-sensitive material applied to the film support can be sensitive to or filter out specific light wavelengths. The different layers work together to make a film that can record a full-color image.

As part of his tour of the Film Sensitizing Division at Kodak, Sandlin met with Dr. Jeffrey Hansen for a couple of days. Hansen has been working on film for over 30 years and is one of the world's leading film design and manufacturing experts. Hansen also explains the physical structure and chemical composition of the light-sensitive layer of film. The chemical structure determines the type of film and how it works.

While we don't want to spoil the tour – and you should watch the entire hour, especially if you're a film photography enthusiast – the basic mechanical process is quite complex. Remember, this is all done in the dark. First, machines unwind the film support base that we saw produced in the first tour video. The support is then coated with gelatinous material with suspended silver halides. It's wet, so it must be solidified through chilling. It's then dried. The coated base is then coated with another layer, chilled, and dried before being rewound.

To see more footage, Sandlin has uploaded additional material on his second channel. The first video is about Kodak's film quality control process. Another supporting video is focused on the chemistry of Kodak film.


Image credits: Smarter Every Day