Even if you put away your photos in a real safe place, thinking they will last forever, you are wrong! All the forces of nature work against you. Just oxygen alone, over time, deteriorates a photo. Plain plastic bags can ruin them. Even the most modern photographic processes are not designed to last for more than a few decades. Black & white photographs, made up of light-sensitive silver halides, last longer. Color photos along with slides are made up of dyes and plastics are even more fragile. Any photograph will eventually succumb to the effects of a hostile environment.
High Temperature and Humidity
The image layer of a photograph is organic. It is susceptible to mold and fungi especially when subject to heat and moisture. Photographs should be stored in a cool, dark, dry place, below about 67º Fahrenheit and under 50% humidity.
Hanging a color portrait photo where the sun hits it directly or indirectly will make it fade in just a few years. To prevent this, keep your photographs out of direct sunlight. If you absolutely have to display it in a bad location, buy special filtered films to put on the window or lacquer spray the photo with ultraviolet inhibiters or both to protect the image. Look at the trouble they went through for the Declaration of Independence document! Having a digital file or an extra photo stored away is a good safety measure.
Wood and Paper Products
Wood and paper produced products contain harmful acids, bleaches and other chemicals that damage the emulsion of your photos over time. Only acid-free products will protect. Always look for “archival” or “acid free” products.
Adhesives & Rubber
Most adhesives, including the infamous rubber cement used often in the past, have harmful chemicals like PVC that will destroy your photographs, turning them yellow or brown!
Household cleaning products, air fresheners, scented candles and fresh paint can, in time, noticeably damage your photos.
Daily Objects, Dust, Dirty Counters, Hard Candy, etc.,
This title comes from actual clients of mine, you know who you are! Obviously, objects you carry every day such as cell phones, big rings of keys, coins, hard candy, etc… and dusty or dirty counters can scratch the surfaces of your prints and negatives. Especially, never lay them face down! Do not paper clip your photos together.