H2S will always be released as the process continues. Hydrogen is more reactive than silver so when tarnish H2S is in the presence of hydrogen ions from any acid HCL, H2SO4, Acetic, etc. The hydrogen ions will react with the sulfur forming hydrogen sulfide, leaving silver ions, which DOES NOT go back on the coin. That is why some large B/W processors used ion exchange to separate out the silver instead of down the drain. Some firms buy xrays from hospitals in exchange for cash and digital prints. The solubility of H2S @ 30 degrees C is about 3 grams/kilogram of H2O. So early use ( fresh) the solution can hold more H2S, later, solubility levels will be exceeded and any old nostril can detect the gas. If any dip is mixed with cool/cold water, as the temperature goes up, the solubility decreases, so more smell. Jim
But the dip is NOT THE SAME as photographic fixer, which is essentially sodium thiosulfate and uses either ion exchange or preferably electrolysis to plate the raw silver. The primary method of recovering silver from developed radiographs is to burn them at high temp and melt the silver from the ash.
So, Jim, what you're saying is that as the smell gets worse, it's a good sign that the dip needs to be changed/refreshed?
Yes, the key word is "worse". If you dilute the dip , the extra volume of water will subdue the smell, and for small jobs, never noticed.I don't know the actual wt/vol of the components. I dilute and use and then discard, keeping the dip in the bottle concentrated. Dip is cheaper than over dipping your coin
This is a good time to focus: Ascetic - a person who renounces the comforts of life and leads a life of austere self-discipline. Acetic - a clear colorless organic acid CH3COOH, with a pungent odor, used in manufacturing.
Earle 42, it's not that I'm obsessive about spelling, it's that other CT-er's in the future probably won't find your posts using Search.
I was being totally serious - I should have qualified my post better. I do appreciate correction. I have a saying I try to live by: When I value " being right" more than what IS right, I am then right...a fool And that can be read two ways.
I had to "like" this, even though "like" isn't exactly the right term, judging from the facial expression it elicited...