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As we browse through old family albums and glance at the yellowing, faded and disintegrating prints from decades ago, we can feel comfortable that today's more advanced prints won't suffer the same fate. Or can we?

Photography has undergone a seismic shift from film to digital, and the printing methods used in producing prints of digital photos have also advanced. This doesn't mean your snaps aren't subject to the same vulnerabilities as prints of old, though. The simple fact is that not enough time has yet passed for anyone to know just how quickly modern prints degrade, but you can be certain that your beloved memories won't be in pristine condition forever.

That said, there are simple yet effective steps you can take to ensure that your prints last long enough to pass through generations. Read on to find out exactly what causes prints to fade, discover simple methods to protect your photos and learn which of the various print methods will maximise the life of your images.

Colour fastness

The central issue to print longevity is colour fastness, which is defined (in terms of photo printing) as the ability of a pigment or dye to retain its original hue over time. All prints fade, but the rate of deterioration is affected by a wide range of physical and environmental factors.

Light is the most commonly cited cause of fading, which is hardly surprising when you consider that a traditional photo is created by light reacting with the chemicals on the surface of paper. The brighter

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the light, the faster an image on an exposed print will fade. Photos displayed on walls or mantelpieces will be exposed to many more hours of direct light than photos safely stowed in an album.

Light damage is not necessarily the biggest threat to most photos, however, as they see the light of day only on special occasions (or to embarrass the kids in front of their new girlfriends). Other environmental factors play a huge part, most notably heat, humidity and the chemicals present in the air.

As well as the 'lightfade' phenomenon described above, traditional silver-halide photos (those created using traditional photo- development processes rather than current inkjet print technologies) also suffer from a problem known as 'darkfade'. This is not caused by a lack of light, but instead refers to non-light-related influences, most commonly the thermal degradation of the colours in a photo at or above room temperature, even when stored in complete darkness.

In addition to heat, relatively high humidity can cause chemical reactions that magnify and hasten change. Rather than damaging the ink particles, high levels of humidity cause them to move about on the paper, warping the image. Regular changes in humidity levels have a similarly damaging effect, and the same goes for changing temperatures. The chemicals in an image expand and contract as the temperature rises and falls, and this can cause the surface of a photo to deteriorate.

Contact with airborne contaminants can also fade the inks in a photo, and this affects inkjet prints more seriously than traditional photo-paper prints. Ozone is the main threat and is one of the reasons why prints still fade, albeit more slowly, when kept in boxes and albums.

Degradation is accelerated by seemingly innocent factors such as the glue used in a particular picture frame or wallet, or the oil left on a photo from a stray fingerprint. Scratches on the surface of an image are an open invitation to such contaminants, and air with higher-than-average levels of dust and dirt, such as that found in busy city environments, will aggravate any damage.