Photo Paper: Long Term Storage

Why I Did It?

When Kodak stopped producing black and white photographic printing papers, I became sensitized to the potential for my favorite papers to suddenly disappear. With Kodak papers gone, I tested other papers and settled on Ilford. But, what if Ilford stops making printing papers?

The idea of stockpiling photographic materials that have disappeared from the market is not new, but I wanted to do it in a way that assured the best chance of success, where success is defined as not running out of paper until I die. Since I was in my mid-sixties at the time, that didn’t really pose much of a challenge. I set a goal of having, at a minimum, a two year supply of paper on hand at all times. Furthermore, I wanted sizes up to 20″x24″.

How To Do It (The Research Phase)

I started this project in late 2016 and I did considerable on-line research. Unfortunately, all I have left are some notes summarizing my findings. There is not a lot of scientific testing of long term storage of unexposed silver gelatin photo paper. Why would there be when it was in plentiful supply? There is, however, quite a bit of research on archival storage of film and finished prints. In addition, I decided to conduct my own on-going tests to confirm whether I was on the right track as the years passed.

We all know that the speed of chemical reactions is reduced by lowering the temperature, so cold storage is the obvious method. Also, it’s well known that fresh photographic paper has a usable life of at least a few years at room temperature. Even old papers that have fogged can be salvaged by adding anti-fogging agents (restrainers), such as benzotriazole, to paper developers. But, I’ve also encountered paper that became fogged after only four years of storage at temps between 65 and 75F. What I was seeking is not just to avoid fog, but to maintain all the original characteristics of the paper for as long as possible.

My research discovered that, indeed, paper will last longer if stored at cold temperatures. The colder the temp, the longer it will last, at least down to 0F. Reducing the temperature has a greater impact on life expectancy than reducing humidity, but condensation must be avoided. For storage, the paper (in its standard cardboard packaging) should be placed in vapor proof laminated (Polyester/Aluminum Foil/Polyethylene) oxygen barrier bags and heat sealed with an iron. The cardboard packaging of the paper absorbs moisture at lower temps, helping to reduce Relative Humidity without drying out the product (as could be the case if desiccant packs were included).

Freezer with Initial inventory of paper & film, vapor proof bags, and wireless cold temp thermometer.

How I Did It

The first, and most costly step was the purchase of a freezer large enough to store boxed of paper as large as 20″ x 24″ lying down flat. That meant getting a chest style freezer. I decided against getting a frost-free freezer to avoid the temperature cycling that comes with the auto defrost operation. I do not know for certain that it would affect the paper, but since the freeze door is rarely opened and the relative humidity in the house is only about 40-60 percent, I don’t have to manually defrost it very often. I have a large low profile plastic storage container upside down on the floor of the freezer to keep the paper up off the bottom by about 5 inches making it slightly easier to reach down to the materials at the bottom.

Paper boxes, various size foil laminate barrier bags, and humidity indicator cards

Vapor proof aluminum Mylar bags are available on eBay in many sizes. They can be sealed quite easily with an ordinary clothes iron. Set the iron to Cotton or Wool and use it dry, so there is no steam. The sealed bags are opened by cutting off the sealed seam, but by getting larger size bags, they can be reused multiple times.

Place the paper & humidity card in bag, squeeze out as much air as possible, and seal bag with an iron.

I stocked up on the Ilford resin coated and fiber papers that I preferred (MGIV and Cooltone), created an inventory spread sheet, taped a humidity indicator card to each box (original packaging), and sealed each box in a barrier bag. When removing the frozen product, I always let it stand at least over night and cut the bag open the seal when it was at room temp to avoid any condensation. Preferably, I just remove the sealed bags as needed, but when a bag contained a 250 sheet box, I remove 125 sheets and refreeze the remainder for later. It’s important to label each bag as to what’s in it because the bags are opaque. I recorded the date code, paper type, size, receipt date, number of sheets for each bag, and the freeze date in a spread sheet. I also note if a package is thawed, paper removed, and then refrozen (Example: Removing a 125 sheet inner bag from a 250 sheet box of Ilford paper.)

Paper bagged and ready to freeze

How Will I Know If I Accomplished My Goal?

As a monitoring scheme, I placed several 8″ x 10″ sheets of Ilford MG IV RC paper (Date Code: 33C504C60, Rcvd 10/6/16) in a paper envelope, sealed the envelope in a barrier bag, and then subjected it to several freeze/thaw cycles over time, occasionally removing one of the sheets and testing it by making a 5″ x 7″ print of a particular negative with a tightly specified enlarger setup using fresh Dektol developer. Additionally, using the remainder of the 8″ x 10″ sheet, I contact print a step wedge using #00, #2, and #5 contrast filters. I compare the resulting print and step wedges against a control which was made on a never-frozen sheet of the same paper in February 2017 when I first began actually freezing paper. My latest test was done in October 2022. So far, the results have been visually identical.

When ready to use, the 8″ x 10″ monitoring sheet is cut into a 5×7, test strips, and step wedge strips.
Test print and step wedge strips from 2017 to 2019 (pink stain on countertop is from selenium toner)