Google says a liter of 9% silver nitrate bath can sensitize over two hundred 5x7 plates. And it can be sunned or boiled to remove contaminants, replenished with silver nitrate crystals, and the pH adjusted with nitric acid.
Unfortunately, I lost half of the silver nitrate since Sunday. There was a leak in the tank, and the silver nitrate seems to have oozed out first, eaten up the silicone aquarium glue and even seem to have warped the plexiglas... I understand now why the few tanks offered for sale are expensive and built literally "like a tank"!
I asked Google some silver nitrate bath questions, and got answers, and follow up questions answers. The jest of it is that to get consistant results, the silver nitrate bath needs to be often checked and maintained so the density for a 9% solution is 1.07 and the pH remains acidic at 4 for ambrotypes, keeping the temperature between 65 and 72. The plates will sensitize faster if the temperature is higher, with a base time around 3 minutes. Over sensitizing can cause fogging, as can a pH above 5. However, lower pH's decrease sensitivity. The level of iodides is also critical to sensitivity, and should remain near saturation level for optimal sensitivity. Higher levels increase grain size. Iodide is primarily sensitive to blue and UV. Adding bromide in 40/60 ratio extends sensitivity into the green range, which is better for portraiture, but with lower speed. Workflow has to get faster as temperatures rise.
I ordered both vinyl and nitrile black gloves, some 5x7 replacement glass for picture frames, a lab hydrometer kit to test the density of the silver nitrate bath, and three 500ml amber bottles. I already have a thermometer.
Now, the problem with the lack of contrast. Well, the wet collodion Ambrotype process is inherently low contrast on purpose, the plates are underexposed and underdeveloped so a weak negative can appear like a positive when placed in front of a black background. We will have to find the right combination of exposure and development time, and that is a bit of an art more than a precise thing. According to some "experts", development time should be cut to 15 or 10 seconds if the image is overexposed and appears too fast, and extended up to 20 seconds or so if the image is slow appearing.
I am concerned my model set up in the dining room may let in too much outside light and might be fogging the plates a little, so I moved everything upstairs to a dark attic room.
Another possible source of fogging actually may simply be the safelight. I have used it for years processing black and white paper, but who knows. So we will have to do a fogging test.
The more pictures I look at and collect from Pinterest though, the more I am leaning towards rough altered images, double exposures, with blurred areas, hand writing, scribbles scratches and blemishes, even painting on them, adding color, gold or silver leaf, collaged paper. In other words a very long way from picture perfect Hollywood portraits...
I like these very much:
I also have always had a fondness for vintage mugshots:
But then that is what I personally like. Once the camera is built and set up, my partner in crime Randy and I can both do our own thing with it, and hopefully get to play and shoot the same models in very different ways, with totally different results. There are after all also plenty of options besides the wet collodion thing we are starting with: dry collodion, liquid silver gelatin emulsion, Ilford reversal paper, X-RAY sheet film , rephotographed photo paper negatives, etc...
We really need to practice pouring, a lot. So I mixed a liter or so of a slightly viscous golden colored gelatin solution to practice blanks with without wasting the collodion.
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