How to keep printed photographs for decades

A photograph printed well and kept badly degrades faster than one printed indifferently and kept properly. The order of priorities is clear.

Light is enemy number one

Ultraviolet radiation chemically breaks down pigments and dyes. Direct sunlight is the most aggressive, but a bright indirect window fades prints over years too. If a photograph really matters, hang it on a wall that never catches the sun, or ask for UV-filtering glass.

Damp and temperature

• Ideal: relative humidity between 30% and 50%, at a steady room temperature.
• Avoid the attic and the cellar. Not because of the average, but because of the swing: warm–cold and wet–dry cycles ripple the paper and lift the emulsion.
• Do not keep photographs on an exterior wall that sweats in winter.
• Above 60% humidity mould appears, and on a photograph that is irreversible.

The album and the box matter more than you think

Ordinary card and many cheap plastics slowly give off acidic compounds that yellow photographs from the inside. Look for materials marked acid-free or archival. The worst kind of album is the sticky-page one with a plastic film over the top, popular in the 1980s and 90s: the adhesive hardens, yellows, and tears the image layer when you try to lift the photo off.

• Store photographs flat, not standing on edge, so they do not curl.
• Handle them by the edges; oil from fingers leaves marks that set over time.
• Do not write on the back with a ballpoint — it presses through and shows on the front. A soft pencil in the corner is enough.
• No paperclips, tape or rubber bands.

A digital copy is the only real insurance

Any physical object can be lost in a flood or a house move. Scan the photographs that matter and keep the copies in two different places — a drive and an online service, for instance. One copy on one device is not a backup.