Some special occasions deserve to be documented through long lasting photographs. You might even hire a professional photographer just to make sure the pictures come out right. For these times, it might be worth the extra expense to get the best film, paper, and printing media as well.
The discussions which follow are general overviews of some things to keep in mind, rather than specific recommendations.
Traditional film photography
Many factors combine to determine if a photograph will last for years or will fade away in months, including the paper on which the photograph is printed, the type of emulsions and dyes used in the printing, and even the type of film used in the camera. Demands for longer lasting photographs over the years have resulted in some improvement in photographic materials from the industry. Today's photographs and negatives, generally speaking, have a longer life expectancy than those of 20 years ago.
Here are a few things to keep in mind when purchasing film and having prints made.
Black and white prints and negatives last longer than any color prints or negatives.
The best paper for printing black and white photographs is high quality, double weight fiber-based paper, rather than the newer polyethylene resin coated papers. The resin coated, or RC, papers are unstable when exposed to UV light, and can crack in high temperatures.
The longest lasting black and white prints are those made with platinum, but silver b&w prints also last for a very long time if they are treated with an image-protective toner.
Color negatives can also last for a long time, especially those in disc form.
Color photographs should not be printed on polyethylene resin coated (RC) color paper. This paper does not hold up well under ultraviolet light, and that heat can cause the polyethylene resin to buckle and crack.
The longest lasting coloring media for use on color prints is pigment based, rather than organic, dye.
Another process available at some photo labs is dye diffusion thermal transfer printing, sometimes also called dye sublimation printing. This process uses heat to vaporize dyes and plant them into paper. This process is relatively new and has not been effectively tested for longevity. However, the photographs usually have UV protective coating on them and are considered to be fairly waterproof. This process is now being offered in desktop printer format for home use.
For more detailed information on the best types of film and paper, please see Permanence and Care of Color Photographs by Henry Wilhelm and Carol Brower. They have tested most films and papers available on the market, and they give their results and recommendations in this book.
Digital Photographs
The digital camera has become amazingly popular with many photographers, from amateurs to professionals. Digital cameras can be easy to use and very convenient: no film is needed, and you can see immediately whether you want to keep the picture you just took or delete it and try again. However, there are a few drawbacks to digital photography, relating to both longevity and access.
Digital pictures can be downloaded from a camera directly onto a computer hard-drive or burned onto an optical disc. In either case, they cannot be seen without the help of a computer or other technological device. For instance, there are digital photo frames available which will display digital photographs from your CD, memory card, or even local area network. This technology may be cutting edge today, and may be available tomorrow, but it may not be around for your grandchildren to use. Technology is changing at an astounding rate, and the photographs that are computer data on a disc today will probably not be readable by tomorrow's version of the computer.
Obsolescence of technology is one factor in the digital field. Another is the longevity of the media itself. Memory cards won't last forever and are fragile to begin with. Optical discs also have a short life-span and can be damaged by heat, light and dust particles (see Protect your CDs and DVDs for more information). Hard drives are known to crash more often than their owners would like.
One solution is to continually migrate the information onto new new media with new technology. Luckily, digital information retains its clarity through each succeeding generation. Today's photographs stored on optical disc can be migrated forward onto tomorrow's micro-optical disc, and then onto a holograph crystal or whatever the next generation of removable storage might be, without losing any of their clarity.
Media migration might be the best solution, but it might not be the most practical one. Photographs are meant to be seen. Printing them out and displaying them in the traditional manner is an option. And, in these days of ever advancing technology and demands for permanence, there are some options available for long-lasting digital photographs.
As in traditional photography, many factors combine to determine if a digital photographic print will last for years or will fade in a few months. The earliest digital photographic printers, papers, and inks created photographs that were gone within two years. The demand for more stable digital prints has caused the manufacturing industry to improve its products. Today, there are a few printers, papers, and types of ink that will create digital photographs that will last nearly 100 years.
The best type of ink for printing a photograph is pigment based, rather than dye based. There are several photographic inkjet printers on the market that specifically use pigment based inks.
There are a number of long lasting types of paper made especially for printing with pigment based inks, and these are well-suited for long lasting photographs. Another option would be a very fine quality art paper. Fortunately, inkjet printers do not require special photograph paper to print on. Be sure to look for "Permanent paper" or paper that is acid free, lignin free, and pH neutral.
The website of Wilhelm Imaging Research Inc.(the same Henry Wilhelm who co-authored "Permanence and Care of Color Photographs" mentioned above) discusses the testing of various photographic printers and gives recommendations. The website is http://www.wilhelm-research.com/