The archival qualities of film we produce are exactly the same as any other film. We are using regular photographic film and professional E6/C41/B&W processing. It is important to note that ‘archival’ has two components – one is the media being stored, the other is the storage conditions. One without the other removes all meaning of the word archival.
Archival storage
Archival storage requires: complete darkness (in an acid-free storage box or album for example), low humidity (centrally heated house for example, the lower humidity the better), and low temperature (20°C or under, the cooler the better). The opposite of archival conditions exist in the tropics as film suffers badly in high heat and the humidity allows moulds to feed on the gelatine.
Under correct storage our colour slides, colour negatives and b&w film will outlive you.
B&W negatives
Your b&w negatives have the advantage of being metallic silver which is archival itself. The gelatine and film base not so much, but to all practical purposes it will last a lifetime – even without perfectly optimal storage.
Colour film
Colour film, negative and positive, is composed of colour dyes only with no silver remaining once processed. Dyes are affected by light, temperature and humidity (think of fading curtains in a window) and they are not permanent. Colour negatives can be archivally stored easily – they are only exposed to intense light briefly when they are used for printing or scanning.
Colour slides, however, by their nature are meant for projection and can be exposed to light and heat for long periods. You can mitigate this by using quality projectors, such as Kodak Ektapro, that remove UV and IR light as far as possible and control heat at the film gate. So slide film will fade over time and the degree of fading depends on the length of projection time above all else. Modern slide film degrades reasonably gracefully and linearly, so even if a slide has started to fade then audience won’t notice until it gets too bad.
Back in the 80s and 90s when we did multiple projector shows in museums and public displays where projectors ran day after day, year after year, the solution to fading was simple – duplicate slides all ready to swap when fading became too obvious. For we never, ever, projected original slides – it was always dupes.
Technical research by the Wilhelm Research organisation (dated at 1992 but still useful, PDF available at bottom of page) give two and a half hours to five and a half hours ‘life’ of slide projection time, depending on ‘amateur’ or ‘museum’ standards. For context, a typical continuous slide show using a modern Kodak projector loaded with 80 slides, changing the slide every 30 seconds over an eight hour day and a seven day week, would give a show life of 3.5 weeks at a minimum – not bad at all! Conversely, project a single slide continuously and you can expect a life of just two and a half hours!
So, do colour slides fade – yes. Will your slides fade – it depends. It is hard to be definitive as there are so many variables but the important thing to remember is you are not projecting original slides, they are copies. Extra slides can be made at any time and in any quantity, all of equal fidelity to the original digital file.
And a personal note. This author has b&w, colour negatives and colour slides going back to the late 1960s and they are all as good as the day they were shot – despite no effort to create special archival conditions. None are exposed to light (in albums, boxes and drawers) and all have been stored in normal domestic and business premises in the UK. So well over 50 years of longevity with minimal effort! Long outliving any digital data I have, which opens the much more scary topic of the lack of digital longevity….
Further reading:
Fading Out: The End of 35mm Slide Transparencies – Electronic Media Review (culturalheritage.org)
Wilhelm Research paper into Projector-Caused Fading of 35mm Color Slides