Digital Media, lifespan longer than microfilm?

The number 1 question I have been asked this month: What else can I store on other than microfilm and have a long lifespan?
This is a very complex question not as simple as Microfilm is good for 50 years and CD is good for 300. Well known libraries and archives live on the LOCKSS principal. Lots of Copies Keep Stuff Safe. The idea is if there are two or more of something stored in different places at least one should survive. 

With this in mind I want to explore a few things:
How long has microfilm/CD lasted and based on these results how long is it expected to last?
Will there be a method for duplication and retrieval?
How expensive is it to maintain the archive?

How long has microfilm lasted?
Microfilm at one time was thought to be a 1,000 year media. It has since been reduced to less than 300 years. A study done by Reilly 1993 showed film decay can be as fast as 30 years when not stored properly.  When stored in sealed containers some films decayed even faster. When stored in acid-free cardboard boxes all films in the archive were affected as they absorbed the acids and air pollution destroying film in very few years.  The industry has documented microfilm as a practice but microfilm has commonly only been able to maintain the image for between 30 and 100 years from date of storage.

If you ever walk into a film archive and smell a ‘vinegar’ smell, like a salad, that is the film decaying.  Film is made from an emulsion, which is a gelatin, which is an animal product often rendered cow bones. According to the Canadian Archives microfilm has an archive life of 300-1,000 years but a practical life of 30-100 years. The film is by nature made from animal products and is by nature biodegradable. If not kept in low temp and low humidity it is like any animal product and degrades very quickly.

How long have CD-R lasted?
Invented in the 1970’s, CD-R’s are now made of many different materials and layers.  ‘GOLD on GOLD’ CD-R’s are engineered to last the longest. Gold on Gold was pioneered by Mitsui and Eastman Kodak. Gold on Gold CD’s have already last since 1990’s and their period of usefulness has not yet been exceeded as of this writing, 31 years. The material is made from Phthalocyanine dye covered in Gold then lacquered to eliminate oxidation. The life of Phthalocyanine dye is estimated to be over 1,000 years but manufacturers of the material are conservative and estimate the useful life at 300 years. Other type of CD media are rated to last 30 to 100 years which is the same as the life of microfilm and non-acid free paper. CD lifespans are measured at room temperature, average room light and humidity. Imagine how long it could be if stored in an archive?

Will there be a method for duplicating microfilm in the future?
Microfilm is already suffering for loss of market. At this time there is only 1 manufacture of duplication equipment in the US and no manufactures of analog based readers. Today a duplicator is $70,000. Getting film for that duplicator and processing that film is also an issue. There are fewer and fewer manufactures of film, chemistry and equipment for micro-graphics. Very soon, within my lifetime I suspect, microfilm as an industry will have died off as it is becoming too expensive to continue. 

Will there be a method for duplicating Cd-R in the future?
Duplication of and retrieval of images from CD-R is simple. There have been over 200 billion cd’s before 2007.  Although the internet, tablet computers and other personal computer devices are phasing out the inclusion of CD-Rom players, most computers still have Optical Disk Players as a means of playing music, movies etc. Blu Ray, SVS and CD-R all have the same physical size and shape but have a different pattern of creation.  They are backwards compatible so CD-R will NOT go away any time soon. 

Duplication side note:
If in a perfect world there were devices to duplicate everything there is still one issue, degraded copies. Analog images, when duplicated, degrade. Digital images never degrade, the image is exactly the same as it was the day it was created. You may have seen this issue when receiving a fax of a copy or a fax of a fax. The image degrades by as much as 12% for every copied made. 5 – 10 copies later the microfilm image is lost. The digital image is still perfect.

Maintaining an Archive 
The rules about archives are:
1: These are the MASTERS and NOT WORKING COPIES
2: Masters are ONLY accessed when the working copy is lost to make a new working copy

How expensive is it to maintain Microfilm in an archive?
Microfilm is one of the most expensive media to maintain properly.  It MUST be kept at 65 degrees Fahrenheit and within 3% of 35% humidity at all times. If the temperature or the humidity varies by more than 5 degrees or humidity by more than 3% it will start to decay very quickly. This is why the film, even though rated for long periods of time, in an application, has only last 30 to 40 years. Microfilm is extremely difficult and expensive to maintain.

A working copy must be created for each location needing one. The average 16mm x 215′ microfilm image contains 6,000 images. A duplicate runs about $45 to $60  so the cost per image is $60/6000 or 1 penny per image. Each site must have a microfilm reader or reader printer. These run between $5,000 and $14,000 each.  Only one person can have access to a copy at one time. Storage must be provided for each copy as well. Film occupies a 3.75 x 3.75 x .75 Inches. this means that 10 file cabinets of paper containing 160,000 images would take 27 rolls of film or about 274 cubic inches of storage per location.

How expensive is it to maintain CD-R archive?
Gold on Gold CD-R need only be kept in a storage area out of direct sunlight and have an office environment with normal relative humidity. These need to be treated as MASTER COPIES so they, like microfilm, should ONLY be handled when the copy is lost or has failed.  CD-R disks have been tested at 85% humidity at 176 degrees Fahrenheit for 1000 hours without major failure.  This test demonstrates over 100 years of normal storage. CD-R have a tremendous tolerance to water and other common elements. We have had clients send us their optical media after being flooded by a hurricane. They were washed, dried and buffed before reading 100% of the data from the disks. The life of CD-R is relative to conditions so a CD-R kept in an archive with Microfilm might last 1,000 years or more. 

Working copies do not have to be created if they are maintained on an existing computer network or on cloud storage.  To compare microfilm to CD as media only, we assume each location will need a working copy of the CD and the number of images stored are the same. The average CD contains 18,000 images. A duplicate CD runs about $3 each so the cost per image is .00016 cents per image. Each site must have a computer with a CD drive a simple laptop will work between $200 and $500. Once brought onto the network MANY people could have access to the same disk at the same time. Storage for the CD-R must be provided as well. A CD in slimline case occupies 5.49 x 4.92 x .2 inches.  This means that 10 file cabinets of paper containing 160,000 images would take 9 cds or about 46.7 cubic inches of space per location.

MY ANSWER  CD-R AND MICROFILM PRACTICAL LIFESPAN IS THE SAME
They are the same. Neither of the media has proven to outshine the other in practical application. If handled badly microfilm and CD-R will probably not live more than 100 years. 
BUT WAIT THAT DID NOT ANSWER THE REAL QUESTION:

What else can I store on other than microfilm and have a long lifespan?
My Previous Answer was CD-R Gold on Gold which is still a fine media.
CD-R has the longevity at this time and at some time in the future there will be a media it can be moved to. New media will cost even less than the current media and have a better lifespan.  

2021 updated answer…
M-Disc, a 1000 year life span media that is not a dye-based media but a media that is physically changed by the reader. It is the same size as a CD, runs in many of the newer CD/DVD/BLU-Ray/M-Disc players and cost is $6 per 50 Gigabytes. In terms of images that is about 275 file cabinet drawers, 1.2 million average business pages, or 2,000 images per penny.

M-Disc/CD-R/DVD are not affected by magnetic fields, power surges, SOLAR Flares, EMP devices, or short term effects of water. As digital storage goes they are, by far, one of the safest media.  If stored carefully within a climate-controlled archive it will outlast its practical life. Practical life is when no devices are created to read it. Very few archives ONLY store/use media. Many move copies of those images to a Cloud or computer network.  There can be MANY copies of the same data all exactly the same as the first and all fulfilling the need for LOCKSS!

Microfilm is very difficult to maintain properly, takes up 5 times the space, can not be easily shared and has 1,000 times greater cost to create and store. So from a pure business standpoint microfilm will die a very sudden death.  The costs for film keep skyrocketing, manufactures leave the market and equipment becomes irreparable.  Microfilm images when duplicated lose their quality and degrade so from a pure archive standpoint they do not meet the standard to keep the best image possible.