Flattening Old Photos

Dear Donia,
What methods can be used for flattening old photographs that have curled?

Q. Dear Donia,

What method(s) should be used for flattening old photographs (black and white prints from the 1920s-50s) that have curled from improper storage in shoe boxes? Most are only mildly curved, but there are some with much more curling. Is there a way to safely flatten them for archival scanning and storage without risk of cracking the image emulsion? Thank you, James

A. Dear James,

Flattening photographs is a delicate process to prevent, as you so rightly point out, cracking the emulsion. The safest way to add moisture to paper- or fiber-based photographs (as compared to modern resin coated photographic papers) is to leave it for a few hours in a tightly closed space with a source of humidity. There are several ways to make a humidification chamber but the one described below is inexpensive and the components are easy to find. NOTE: exposing paper to high humidity for prolonged periods is usually not recommended because of the potential for mold growth. However, a few hours in the humidification chamber will do no harm if the artifact is allowed to dry soon after it has been unrolled. 
Necessary Supplies: 
  • A large, long, shallow bin with a tight fitting lid (for example, an under-the-bed storage bin)
  • Nylon window screening (easily found at your local hardware store)
  • Spun polyester—Hollytex is very smooth and will not imprint on the emulsion. Hollytex can be purchased by the yard from Talas (talasonline.com) - product number 3249 would be the best choice.
Begin the humidification process early in the day. It may take several hours, and objects should never be left in the chamber overnight. 
Using a plastic bin:
  • Line the bottom of the bin with a damp towel (use cold water).  Any excess water should be removed from the towel by wringing it out. 
  • Place 4-5 layers of nylon window screening on top of the damp towel.
  • Place a piece of spun polyester on top of the screening.
  • Place the rolled or folded items on top of the polyester.
  • Fasten the lid. 
  • Wait. Check the items after about an hour. If they are not completely relaxed, replace lid, wait another hour, and check again. Repeat until the items have relaxed.
Do not leave objects in a humidity chamber for more than eight hours as this can lead to mold growth.  
Necessary Supplies: 
  • Sheets of clean blotting paper—10 or 30 point blotter paper can be purchased by the sheet from Talas
  • Spun polyester 
  • Stiff, smooth material like Plexiglas or Masonite the same size or larger than the blotters
  • Weights such as bricks
Remove the relaxed photos from the humidification chamber a couple at a time, replacing the lid each time. Place the items on a piece of dry blotting paper lined with a piece of spun polyester and unroll it. Handle items carefully: damp paper can be fragile, especially if it is already torn. As each artifact is unrolled, it should be placed in a flattening/drying package (see diagram below). If using wood products for the top board, it must be flat and smooth, without any warping. Weight with bricks, but not too many to prevent damage to the emulsion layer. Use just enough to provide some restraint but not so many that would crush the paper. Depending on the size of blotter you are using, 2-3 should suffice. Leave the photos weighted until they are dry. Several photos can be dried in a stack with blotters between each. 
  • Brick
  • Plexi/Masonite board
  • Blotter
  • Hollytex
  • Photos
  • Hollytex
  • Blotter
  • Level, smooth table top
Flattening photos
Although most photographs can be safely humidified, photographic emulsions may soften slightly, so extra care is necessary during flattening. Humidify and flatten a test photo to get used to the process before diving in and humidifying all of them. Please be sure to use caution at each step so that you don't damage your photographs. Taking it slowly will allow you to monitor and catch any problems early.
Thank you for your question and please don't hesitate to ask if you have any more.