Public Lab Research note

Bayou Sauvage Results 2: reflections on fixing process

by sara | July 13, 2012 22:53 13 Jul 22:53 | #2800 | #2800

On Thursday 12th I fixed the first set of test Hydrogen Sulfide photographic paper strips from Bayou Savage. Fixing the strips presented some problems:

  1. Identification of the strips during fixing. As all the strips in the tubes are unlabelled once removed from the canisters is was important to figure out how to fix them without confusing the strips.

  2. Each strip needs to fix for five minutes and we had 32 strips all together so fixing them individually would take a long time.

  3. This all has to be done in low light environment of the darkroom

Before traveling to darkroom

To solve these problems I created a fixing board, the top of a hard clear plastic file folder. I labelled the rack vertically 1-8 and horizontally A-D with a Red Sharpie. With the idea that the whole board could be submerged in fixer.

Second because I was worried about mixing up the samples in the low light, I made large labels for the side of each canisters. I took the further step of repacking the box so the sets of four samples we separated so I wouldn't have to resort them in the darkroom.

In the Darkroom

I then gathered everything up and headed to the darkroom at AS220. In the darkroom I arranged all of the materials I would need before turning off the lights. I filled a tray with fixer, and prepared a tray for washing. I put the pins and all of the canisters and board out on the side. Then turned off the light and began work in the safe light.

With the safelight on

Then with the safe light on in the dark room I individually pinned the strips in the appropriate column and row.

I did a test run with just sample 1 A, B, C and D to make sure they stayed put during the fixing process. I submerged the whole plastic board in the fixer and waited for 5 minutes, then rinsed the whole board with cold water twice. It became clear that the strips needed to be pinned at both the top and the bottom because the strips come out curled up. For the first row I pushed the strips that poked out into the fixer with the tongs.

As the system worked well for the first row, I put the remaining 5 rows on to the first plastic rack. Pushing the pins through the hard plastic was no small feat. My thumb was killing me by the end. So I decided not to do the second row of pins in each sample but rather to weight the strips down with some handy metal rods.

This worked out okay but the rods tended to slip so I fixed the first rack for an extra 2 minutes to ensure that all of the strips were fully fixed.

The second rack of rows 6-8 went far better, because my thumb was numb and I realized that it is easier to push the pin through if the board was not resting on a hard surface. So I positioned the board across the file folder box in order to fully put the pins in.

I also realized on the second board that I'd forgotten to take off the control dots on the first board! I removed them on the second board and could tell that sometimes they left a white circle as expected and other times a darker circle. I tried to keep the dots to figure out which color dots were leaving the darker circles. I stuck the dots on next to the sample canisters from which they had come once I noticed the color difference.

I then submerged the second board in fixer for five minutes and wash them twice with color water. The best part about the plastic file folder board was that I could use the bottom bin as a top and safely transport the strips home so they could dry.

Other interesting occurrances:

  1. a Spider had moved into canister 7a
  2. the sizes of the strips were very variable, in the future I think we should try to cut them all to same size
  3. it is important to removed the dots before fixing, I tried to remove them from the first board after fixing and the wet dots just fall apart. You can see this on samples 4 a and b.
  4. Some samples actually showed color change, for analysis of this see the next research note.

Time to analyze the samples!!


Do you think it would work to just fix them right in the containers, if they were just cut big enough to not overlap, you could dry them in the containers too? That way, if there was a map of where each container was located on site, once the strips are fixed you could just either write with sharpie on them or just document them and mark the number/location in the documentation.

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Hey Megan, I think that sounds like a great idea. Particularly if you can set up a dark space on site to do the fixing. We should definitely try this out.

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