Quote Originally Posted by Smudger View Post
Google "Lugols Solution". A mixture of iodine and iodide. Apply to hair line or black spot with a fine brush,on the dry print. Rinse and re-fix to clear the brown stain. Bleaches back to paper base white.
It works very well.
Usually a hair line is too fine to be removed with bleach and I wouldn't recommend an Iodine/Iodide bleach on print as it's a very aggressive cutting bleach. I used Iodine/Iodide bleach extensively for graphics work in the 1970's & 80's and it is very useful.

Ian