This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Torn Film On Negative. Where the film has been torn away from the glass by careless manipulation during development, fixing or washing, it can be repaired by carefully laying the torn film back in place with a soft brush while the negative is still in the water. Remove it at once and dry it. Then retouch the negative and spot the print in the usual way.
668. Where the film has been torn out entirely, it is best to flow a little collodion or gelatin on the place, as it is almost impossible to apply pencil or color to the glass itself. With a gelatin or collodion surface on which to work, carefully penciling or applying of India ink will remove most of the signs of the tear. It is best to pencil or color the torn place a little darker than the surrounding film, and the print can then be brought up to the proper color afterward.
669. In applying color or India ink to a large spot or a long one, never apply it all over the spot, but apply the color to the center. It will gradually spread to the edges of the spot and fill up the opening, whereas if the color is applied working from the film to the center of the spot, the film will attract all the color, making it impossible to cover the hole.
 
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