Thursday, January 16, 2014

There are two sides to every story...

...or in the this case, every sheet of film.

top: emulsion
bottom: base

Emulsion and Base

When handling negatives, wether they are flexible or glass, it is important to be aware of the sides of the film. Film is made up of a base side and an emulsion side. The base is the substrate of the film. It is the surface that the "image" is sitting on.

The emulsion side, is the light sensitive coating that is applied to the base. The emulsion side of the film will have a dull matte look to it. Sometimes, if you have a very underexposed film and you are holding it over a dark surface, the image can appear to invert to a positive.

The base of the film is highly reflective. With glass, it looks like a sheet of glass. If you are working with flexible sheet film each sheet should have a notch code in the upper right corner. When the notch is in the right corner, the emulsion is facing you. Each film type also has a unique notch code, so the photographer knows what kind of film is being loaded or unloaded in the dark. It must have been difficult for plate photographers to be aware of the emulsion side during loading and processing.

There are many analogies for the base and emulsion. I remember someone describing it to me as, the base is the slice of bread and the emulsion is the butter.  Just like bread tastes better with butter, a glass plate image looks better with an emulsion. The emulsion is fragile and can be easily scraped or scratched, and at times can flake off of the base. This is why it is important to know what side of the film you are handling.

Inspection and Care

When viewing the images on the light table you will want the emulsion to be up, so it will not be scratched on the glass table top. Keep in mind, this will result in the image appearing backwards. It is also important to be careful when the emulsion is up when reviewing the images with a loupe. I try to just have the loupe float above the emulsion, until I find the spot that I would like to inspect, then I carefully set it down on the film. 

Glass plate negative emulsion lifting off of the base.
When sleeving the negative into a new archival negative sleeve it is important to have the seams of the envelope facing the base of the film. This will help protect the emulsion from any damage from glue or harder edges.

Gloves or No Gloves

I use a Kodak, camel hair brush to sweep away any debris left over from the old negative sleeve. A light quick sweep of the base and emulsion is done before going into the new negative sleeve.  You may also notice that I am not wearing gloves. When handling negatives, the oil from fingers can leave prints on the emulsion. However, I found that the danger of working with gloves and not having a feel for the negative could result in dropping the negative. I carefully wash and dry my hands frequently to reduce the chances of leaving fingerprints. Also, I handle the negatives only by the edges of the film. With flexible film, cotton gloves are a good idea, or even a latex glove gives better grip, but can be uncomfortable when working for long periods of time.

More sleeving and sorting today. Next I'll update some of the biographical information that I discovered recently. Stay tuned...

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