Equipment Needed:

• 2 or 3 trays large enough to process papers (glass cooking trays work well)

• darkroom (or a room that can be made relatively dark – bathrooms work well)

• clips hung on a string to dry the paper on (or lay flat on some paper towels)

• 100% cotton paper (the heavier weight paper the better)

• rubber gloves (dishwashing gloves are fine)

• aluminum foil & large envelopes (for storing the finished paper)

Chemicals Needed: (available from most chemical suppliers)

• 16 g of potassium bromide (KBr) (a solid)

• 15 g of citric acid (a solid)

• 1.5 g of gelatin (also available from the supermarket – get unflavored!)

• 36 g of silver nitrate (AgNO₃) (a solid)

• 60 g of sodium thiosulfate (Na₂S₂O₃) (a solid)*

• 1 g of sodium carbonate (Na₂CO₃) (a solid)*

*the last two can be substituted with commercial photo fixer.

Preparing the Chemicals: (you will make 3 solutions, label each)

Gelatin Solution: Dissolve the potassium bromide, citric acid, and gelatin in 300 mL of warm (40-50°C) water. Stir for 2-5 minutes until all gelatin is dissolved and allow to cool.

Silver Nitrate Solution: Caution, this solution will stain your hands brown and should only be handled using gloves. Dissolve the silver nitrate in 300 mL of water, stir well.

Fixer Solution: Dissolve the sodium thiosulfate and sodium carbonate in 400 mL of water, stir well.

Preparing the Paper:

Label one side of a paper “back” with a pencil.

Part I: Pour the gelatin solution into a clean tray. Float a sheet of paper on the surface of the solution with the back side facing up. Be sure to gently tap out any air bubbles trapped between the paper and the surface. Wait approximately 3 minutes. Gently slide the paper off the surface of the solution and hang it up to dry using the string of clips (or lay flat, back side down, on some paper towels). This step does not need to be done in the dark. Allow the paper(s) to dry completely.

Part II: For this step you will need almost total darkness and gloves. A small red colored light or a tiny flashlight pointed away from the working area is OK. Pour the silver nitrate solution into a clean tray. Float each sheet of paper from part I in this solution for 3 minutes and hang dry as before. Again, be sure the back side of the paper faces up and keep the lights off when drying. When the paper is completely dry, store each sheet inside an envelope wrapped in aluminum foil to keep the light out. Your paper is now ready to use!

Printing:

Before printing prepare a clean tray of fixer solution and a second tray of water.

You can either use real photographic negatives or make your own by using digital images and printing as negatives on photocopier-safe transparencies using a laser printer (most photo editors can turn pictures into negatives). Place the negative over the front of the paper and expose to a lamp or sunlight for a few seconds to several minutes (you’ll need to experiment!). When the image is ready, soak (do not float) in a tray of fixer (thiosulfate) solution for 6-10 minutes with gentle agitation, then soak in water for 6-10 minutes, and finally dry. Your classic style print is ready for framing!

Storage & Waste:

The solutions described should last for many many prints and can be stored safely in dark brown glass or nalgene bottles. As always, dispose of chemicals properly when finished with them. The silver nitrate particularly should not be poured down the drain, and in fact silver metal can be recovered from this solution!

-Dr. Ethan Gallogly, SMC College

e-mail: gallogly_ethan@smc.edu