Cyanotypes are sensitive to alkali and must not be stored in buffered products or in alkaline conditions, where they will rapidly bleach.
Le Secq chose to make cyanotypes of his work because they were far more stable than silver-based prints. Cyanotypes do show some fading in strong light, but after a relatively small initial loss, this process is generally reversed on dark storage. They can be safely displayed in normal gallery/museum lighting levels.
