Negative error
As a negative error in are Analog Photography faulty images on photo negatives referred to as the consequences of faults in the film development can occur.
Irreversibility
The chemical process that takes place during development is not reversible. Existing "data" on the medium are therefore irretrievably destroyed in almost all cases. So you can only avoid negative errors, but with a few exceptions you cannot repair them afterwards.
Types of negative defects
Pinholes / wrinkles
Pinholes are tiny holes in the photo emulsion layer that look like they were made by pinpricks. They form when the emulsion is exposed to too great a difference between the pH values of the alkaline developer and an acidic stop bath. Similar errors known as "wrinkles" can arise with large temperature fluctuations during development.
Vesicles
Bubbles form when the developer has a high surface tension (water with a high content of calcium) and due to insufficient mechanical movement. The result is underdeveloped or undeveloped areas.
Development puffs
If the negative developer is filled in too slowly and the container is then moved too little, too slowly or too steadily, the developer rolls over the negative in waves. At the beginning he works quickly and strongly, but increasingly weakens his effect. The result is an irregular development with transverse stripes. These "development clouds" arise at the points with (too) strong developer action.
Gradient stripes
Gradient streaks form as a result of insufficient developer fill level combined with insufficient movement. The developer is then used up in the places where it has already developed the negative, stops at the negative and slowly sinks down the layer as its density increases. The resulting streaks usually appear from the edge of the film towards the center.
Limescale stains / dirt
If drops of hard, chalky water remain on the film and dry, the water evaporates and the scale remains on the film. Dust deposits on the damp film result in similar soiling.
Lubrication points / scratches
Mechanical influences leave smeary spots and / or scratches on the finished negative.
Colored negatives
If the negative becomes tinged in color, usually pink, violet, blue or reddish, this is the result of insufficient concentration of the developer (with some types of film in the fixer ). Then either the antihalation layer is not removed sufficiently or the dyes used for sensitization remain on the film. Such negative errors can be corrected for some types of film by exposing them to sunlight. Then the paint residues fade out.
Subsequent staining
Yellowish or brownish spots can still appear after storage for some time if the negative has not been sufficiently watered. Such negatives can be watered afterwards, but this can only prevent the formation of new spots, but not correct existing errors.
Darkening
Insufficient fixation can result in darkening (even spotty) after a short period of storage. This process can also be stopped, but not reversed, by re-fixing and thorough re-watering.
Obfuscation
Obfuscation is the result of overdevelopment of a film or insufficient fixation. It occurs when the prescribed ratios of concentration, temperature and duration have not been adhered to during development and / or fixation. Fixing it again can help.
Transparency / opacity
"Fluff", almost transparent negatives are the result of insufficient development, but can also have been created beforehand due to underexposure when taking the picture. The opposite error, very "hard" and dark, almost opaque negatives, is created analogously through overexposure or overdevelopment.