Public Lab Research note

Procedure for Fixing H2S photographic paper strips

by sara | March 29, 2012 17:31 29 Mar 17:31 | #1581 | #1581

Once test strips have been exposed to H2S laden air, the canisters containing the strips should be resealed so they can be fixed in a dark room.

Gather up test strips and in a dark room fix them by:

  1. Mixing up the fixative, we have tried:

Kodak Fixer for Black & White Film & Paper, this powder when makes 1 Gallon (3.8L) of fixer.

Put on gloves and follow the directions on the back of the packet: mix 3 L of water with the powder (not 3.8 L of water then adding the powder as I did on my first try). Stir the mixture gently until it the powder dissolves completely so the liquid looks clear. This took us about 10 minutes on first try.

  1. Place the strips into the fixer for five minutes.

  2. Remove the strips from the fixer and wash the twice with cold water.

  3. Leave the strips on a rack or hang them to dry for 12 hours. As they are now fixed they can be dried in light or in the dark.

  4. The fixer is reusable so store it in a 1 gallon light safe jug. This should be poured in carefully using a funnel so you don't splash it around too much. Wash skin thoroughly if you get any on you.

Problems we ran across on first try: 1. We misread the directions and mixed the powder with 3.8 L of water so our fixer was too dilute.

  1. It is difficult to tell which strips are which and the fixer can remove permanent marker so we scratched roman numerals into our pieces of photographic paper before fixing so that each strip was properly marked.

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