Hydrogen Sulfide Testing With Black and White Film
Following is a procedure for Hydrogen Sulfide testing using Ilford Multigrade IV RC Deluxe MGD.1M B&W Paper which has been borrowed from the procedure published in Evaluation of a Novel Passive sampling Technique for Monitoring Volcanic Hydrogen Sulfide by Horwell, Allen, Tamsin and Patterson.
Treated sections of photographic paper are exposed to atmospheric Hydrogen Sulfide. "H2S reacts with free radicals including the hydroxyl (OH) and4 nitrate (NO3) radicals, ultimately forming sulfur dioxide, with an H2S lifetime in the troposphere of several tens of hours." - Hydrogen Sulfide (H2S) is the sole tarnishing agent for silver.
Achieving a uniform distribution of silver is difficult to achieve and essential for accurate test data (results). This method utilizes Ilford Multigrade IV RC Deluxe MGD.1M B&W Paper - a chemically developed black and white photographic film - containing a uniform distribution of silver halide retained in a thin surface layer (~0.005mm) of gelatin.
Materials - (with links)
Ilford Multigrade IV RC Deluxe MGD.1M B&W Paper (35 sheets $18)
-as it should seem that Glycerol and Glycerine are roughly the same compounds we will use Glycerine as it is more readily available. (8oz $1)
Kodak Photoflo 200 (16oz $8)
Preparation of the samplers may be summarized as follows:
. In a darkened room, cut black and white resin-backed photographic paper into strips.
. Use plastic tweezers to place the strips face down in the glycerol solution (to reduce the effects of any light in the darkened room) for five minutes.
. Remove the strips from the solution and let them drain onto a paper towel. Leave strips to drain for five minutes before transferring to a dark place to allow drying to occur (at least 12 hours).
. Place strips in labelled black cylindrical photographic film containers. Replace container lids during storage. The samplers remain inactive until exposed to H2S-laden air.
. Expose the samplers in the field for a set length of time. Collect the samplers.
. Fix the samplers using a photographic fixing solution (e.g. Kodak UNIFIX powder or solution and water) in subdued light. Leave in the solution for five minutes before thoroughly washing twice in cold water.
. Drain the samplers as before and leave to dry for at least 12 hours.