What is glue streaking?
This composite image shows glue streaking on two stereographs. This is most prominent on the wall of the vertical structure next to the ferry Solano (left) and on the roof of the San Francisco residence (right). A series of black parallel lines drawn on the images point to the streaking and show the orientation of the alternating increased and decreased density which is thought to be damage to the albumen emulsion due to chemical interaction with the glue used to attach the image to the cardboard mount. The streaking likely results from the pattern of the glue application to the back of the print from a glue brush, possibly due to sulfur compounds in the glue. Glue streaking is one of the most troublesome types of damage because it extremely difficult or impossible to remove when doing digital restoration. Having such artifacts which differ between the left and right image can also be disconcerting when seen in the stereo viewer where each eye sees one of the two images of the stereo p
