Glass negatives were used to produce photographs circa 1850 through the 1920s. Most are now in archives or museums, though some are still found in individual photograph collections. Cleaning glass negatives is done in two steps, being basic mechanical cleaning, then treatment of the emulsion layer. Treating the emulsion layer is best left to a conservator, as it requires specialty chemicals and a knowledge of photograph conservation. However, the mechanical cleaning and cleaning the non-emulsion side requires no special knowledge, just a steady hand.
Instructions
1. Don the surgical gloves before handling the negatives, to prevent damaging the glass or emulsion with oils and acids from your fingers.
2. Identify the emulsion side of the negative. It will have a dull or silvery sheen. The glass side will be smooth and more shiny.
3. Blow dust off both sides of the negative with the air bulb. Do not use canned air or blow on it with your mouth when cleaning a glass negative because both methods can result in unwanted moisture contacting the negative.
4. Brush any remaining dust off of the negative with the sable brush. Brush the emulsion side only if the emulsion is not flaking. Shake the brush frequently and vigorously, to remove any dust and to avoid re-introducing dust to the negative.
5. Moisten the cotton cloth slightly with ethyl alcohol and carefully clean the glass side of the negative. Use caution near the edges so that the ethyl alcohol does not leech onto the emulsion side.
6. Dry the glass side with a clean cotton cloth.
