This white 12-pack of Stabilo-All Pencils from Archival Methods is designed to write on photographs, film negatives, glass, and metal surfaces. Stabilo-All Pencils can write on plastic-coated paper, whereas regular graphite pencils do not.
The pencils' output is water-soluble and can be wiped easily off a smooth surface with a damp cloth. (Markers and inks are not as conservation-friendly as they are not reversible once used.) If written on the back of a photograph or paper, markings can be erased easily as well. It is recommended to write lightly on photographs and other materials so as not to pressure-transfer, which may cause the writing to become visible on the opposite side.